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The photosynthetic assemblies in bacteria, as critical structures in early evolutionary photosynthesis, are pivotal for understanding the molecular mechanisms of photosynthesis and for the design of artificial photosynthetic systems. In recent decades, various artificial systems based on synthetic molecules have been developed to mimic these photosynthetic assemblies from structures to functions. This review summarizes the latest advancements in mimicking the photosynthetic assembly systems, discussing three fundamental models: the chlorosome and related complexes in green bacteria, the chromatophore and reaction center system in purple bacteria, and the phycobilisome and photosystem II (PSII) in cyanobacteria, along with their representative mimicking systems. We also address the challenges and unexplored areas in the simulation of photosynthetic systems. [ABSTRACT FROM AUTHOR]

Aerobic anoxygenic phototrophic (AAP) bacteria are a common part of microbial communities in the sunlit ocean. They contain bacteriochlorophyll a (BChl a)‐based photosystems that harvest solar energy for their metabolism. Across different oceanic regions, AAP bacteria seem to be more abundant in eutrophic areas, associated with high chlorophyll concentrations. While most previous studies focused on surface samplings, there is limited information regarding their vertical distribution in euphotic zones of the major ocean basins. Here, we hypothesized that AAP bacteria will follow a similar structure to the chlorophyll depth profile across areas with different degrees of stratification. To test this hypothesis, we enumerated AAP cells and determined bulk water BChl a concentrations along the photic zone of a latitudinal transect in the South and Central Atlantic Ocean. Overall, the distribution of AAP bacteria was highly correlated to that of chlorophyll a and to the abundance of picophytoplankton across both vertical and horizontal gradients. Furthermore, estimated light energy captured across the water column showed that, while AAP bacteria share a common latitudinal pattern of light absorption with picophytoplankton, they display a unique vertical arrangement with highest photoheterotrophic activity in the top 50 m of the surface ocean. [ABSTRACT FROM AUTHOR]

Therapeutic mRNA vaccines have become powerful therapeutic tools for severe diseases, including infectious diseases and malignant neoplasms. mRNA vaccines encoding tumor‐associated antigens provide unprecedented hope for many immunotherapies that have hit the bottleneck. However, the application of mRNA vaccines is limited because of biological instability, innate immunogenicity, and ineffective delivery in vivo. This study aims to construct a novel mRNA vaccine delivery nanosystem to successfully co‐deliver a tumor‐associated antigen (TAA) encoded by the Wilms' tumor 1 (WT1) mRNA. In this system, named PSB@Nb1.33C/mRNA, photosynthetic bacteria (PSB) efficiently delivers the iMXene‐WT1 mRNA to the core tumor region using photo‐driven and hypoxia‐driven properties. The excellent photothermal therapeutic (PTT) properties of PSB and 2D iMxene (Nb1.33C) trigger tumor immunogenic cell death, which boosts the release of the WT1 mRNA. The released WT1 mRNA is translated, presenting the TAA and amplifying immune effect in vivo. The designed therapeutic strategy demonstrates an excellent ability to inhibit distant tumors and counteract postsurgical lung metastasis. Thus, this study provides an innovative and effective paradigm for tumor immunotherapy, i.e., photo‐immunogene cancer therapy, and establishes an efficient delivery platform for mRNA vaccines, thereby opening a new path for the wide application of mRNA vaccines. [ABSTRACT FROM AUTHOR]

The photosynthetic amoeba, Paulinella provides a recent (ca. 120 Mya) example of primary plastid endosymbiosis. Given the extensive data demonstrating host lineage‐driven endosymbiont integration, we analysed nuclear genome and transcriptome data to investigate mechanisms that may have evolved in Paulinella micropora KR01 (hereinafter, KR01) to maintain photosynthetic function in the novel organelle, the chromatophore. The chromatophore is of α‐cyanobacterial provenance and has undergone massive gene loss due to Muller's ratchet, but still retains genes that encode the ancestral α‐carboxysome and the shell carbonic anhydrase, two critical components of the biophysical CO2 concentrating mechanism (CCM) in cyanobacteria. We identified KR01 nuclear genes potentially involved in the CCM that arose via duplication and divergence and are upregulated in response to high light and downregulated under elevated CO2. We speculate that these genes may comprise a novel CO2 delivery system (i.e., a biochemical CCM) to promote the turnover of the RuBisCO carboxylation reaction and counteract photorespiration. We posit that KR01 has an inefficient photorespiratory system that cannot fully recycle the C2 product of RuBisCO oxygenation back to the Calvin‐Benson cycle. Nonetheless, both these systems appear to be sufficient to allow Paulinella to persist in environments dominated by faster‐growing phototrophs. [ABSTRACT FROM AUTHOR]

Marine biogeochemical cycles are built on interactions between surface ocean microbes, particularly those connecting phytoplankton primary producers to heterotrophic bacteria. Details of these associations are not well understood, especially in the case of direct influences of bacteria on phytoplankton physiology. Here we catalogue how the presence of three marine bacteria (Ruegeria pomeroyi DSS‐3, Stenotrophomonas sp. SKA14 and Polaribacter dokdonensis MED152) individually and uniquely impact gene expression of the picoeukaryotic alga Micromonas commoda RCC 299. We find a dramatic transcriptomic remodelling by M. commoda after 8 h in co‐culture, followed by an increase in cell numbers by 56 h compared with the axenic cultures. Some aspects of the algal transcriptomic response are conserved across all three bacterial co‐cultures, including an unexpected reduction in relative expression of photosynthesis and carbon fixation pathways. Expression differences restricted to a single bacterium are also observed, with the Flavobacteriia P. dokdonensis uniquely eliciting changes in relative expression of algal genes involved in biotin biosynthesis and the acquisition and assimilation of nitrogen. This study reveals that M. commoda has rapid and extensive responses to heterotrophic bacteria in ways that are generalizable, as well as in a taxon specific manner, with implications for the diversity of phytoplankton‐bacteria interactions ongoing in the surface ocean. [ABSTRACT FROM AUTHOR]

Cyanobacteria utilize CO2 and HCO3− as inorganic carbon (Ci) sources. In low Ci, like in ambient air, cyanobacteria efficiently collect Ci using a carbon concentrating mechanism (CCM). The CCM includes bicarbonate transporters SbtA, BicA and BCT1; the specialized NDH complexes NDH‐13 and NDH‐14, which convert CO2 to HCO3− in the cytoplasm; and carboxysomes that are protein shell encapsulated ribulose‐1,5‐bisphosphate carboxylase/oxygenase (RuBisCo) and carbonic anhydrase containing bodies in which the first reaction of carbon fixation occurs. Ci‐dependent regulation of bicarbonate transporters and specialized NDH complexes, especially the regulation of the SbtA transporter, are well understood. CcmR (also called NdhR), CyAbrB2, CmpR and RbcR act as transcription factors regulating CCM genes. Ci signalling molecules detecting the metabolic status of the cells include 2‐oxoglutarate, which accumulates when the Ci/nitrogen ratio of the cell is high, and 2‐phosphoglycolate, the first intermediate of the photorespiration pathway, whose accumulation indicates low Ci. These signalling molecules act as corepressors and coactivators of the CcmR repressor protein, whereas 2‐phosphoglycolate and ribulose‐1,5‐bisphosphate activate transcription activator CmpR. In addition, bicarbonate or CO2 activates the adenylyl cyclase that produces cAMP, and ATP/ADP/AMP provide information about the energy status of the cell. Less is known about the molecular mechanisms regulating carboxysome dynamics or how production, activity and degradation of photosynthetic complexes are regulated by prevailing Ci conditions or which mechanisms adjust cell division according to Ci. This minireview summarizes the present knowledge about molecular mechanisms regulating cyanobacterial acclimation to prevailing Ci. [ABSTRACT FROM AUTHOR]

Microbially mediated arsenic redox transformations are key for arsenic speciation and mobility in rice paddies. Whereas anaerobic anoxygenic photosynthesis coupled to arsenite (As(III)) oxidation has been widely examined in arsenic‐replete ecosystems, it remains unknown whether this light‐dependent process exists in paddy soils. Here, we isolated a phototrophic purple bacteria, Rhodobacter strain CZR27, from an arsenic‐contaminated paddy soil and demonstrated its capacity to oxidize As(III) to arsenate (As(V)) using malate as a carbon source photosynthetically. Genome sequencing revealed an As(III)‐oxidizing gene cluster (aioXSRBA) encoding an As(III) oxidase. Functional analyses showed that As(III) oxidation under anoxic phototrophic conditions correlated with transcription of the large subunit of the As(III) oxidase aioA gene. Furthermore, the non‐As(III) oxidizer Rhodobacter capsulatus SB1003 heterologously expressing aioBA from strain CZR27 was able to oxidize As(III), indicating that aioBA was responsible for the observed As(III) oxidation in strain CZR27. Our study provides evidence for the presence of anaerobic photosynthesis‐coupled As(III) oxidation in paddy soils, highlighting the importance of light‐dependent, microbe‐mediated arsenic redox changes in paddy arsenic biogeochemistry. [ABSTRACT FROM AUTHOR]

Unveiling biomedical functions of tumor‐resident microbiota is challenging for developing advanced anticancer medicines. This study demonstrates that isolated intratumoral bacteria, associated with natural purple photosynthetic bacteria, have inherent biocompatibility and strong immunogenic anticancer efficacies. They preferentially grow and proliferate within a targeted tumor milieu, which effectively causes immune cells to infiltrate the tumor and provoke strong anticancer responses in various syngeneic mouse models, including colorectal cancer, sarcoma, metastatic lung cancer, and extensive drug‐resistant breast cancer. Furthermore, these functional bacteria‐treated mice exhibit excellent anticancerous responses and have significantly prolonged survival rates with effective immunological memory. Light‐harvesting nanocomplexes of microbial consortia of intratumoral bacteria and purple photosynthetic bacteria can diagnose tumors using bio‐optical‐window near‐infrared light, making them useful theranostic agents for highly targeted immunological elimination of the tumor and for precisely marking tumor location. [ABSTRACT FROM AUTHOR]

Sponges are animals that feed by filtering water through their perforated body. We examined the in situ diel dynamics of sponge metabolism by continuously measuring the oxygen concentrations in the water inhaled and exhaled by undisturbed sponges. A clear daily pattern of oxygen removal was evident for six of the seven species we studied with their nocturnal oxygen removal being almost double the diurnal values (+ 86 ± 57%). Oxygenic photosynthesis by the sponge's symbiotic or endolithic phototrophic microbes may explain some of the diel difference, but significant day–night differences were also observed in three sponge species for which no evidence of photosynthetic activity (tested with imaging pulse‐amplitude‐modulation Fluorometry) was found. Mean oxygen removal (± 95% confidence interval for the mean) per species ranged from 1.7 ± 1 μmol O2 per liter (hereafter: μmol O2 L−1) for the low microbial abundance (LMA) sponge Callyspongia siphonella to 30.5 ± 10.5 μmol O2 L−1 for the high microbial abundance HMA) sponge Theonella swinhoei with considerable variation in oxygen removal across all scales (minutes to hours, within and among specimens). Events of high oxygen removal (> 50 μmol L−1) were regularly observed for five of the seven species and were predominantly nocturnal, occasionally lasting several hours. The high variability in oxygen removal stresses the need for long‐term in‐situ measurements of benthic suspension feeders metabolism. [ABSTRACT FROM AUTHOR]

The outstanding metabolic versatility of purple non‐sulphur bacteria makes these organisms an ideal candidate for developing photobioelectrochemical systems applicable in contaminated environments. Here, the effects of 2,4 dinitrophenol, a common contaminant, on purple bacteria photobioelectrocatalysis were investigated. The aromatic contaminant clearly affects current generation, with an enhanced photocurrent obtained at low dinitrophenol concentrations (0.5–1 μM), while higher values (up to 100 μM) resulted in a gradual decrease of photocurrent. The obtained electrochemical evidence, coupled to spectroscopic studies, allowed verifying the viability of the bacteria cells after exposure to dinitrophenol, and that no alteration of the photosynthetic apparatus was obtained. The results indicate that high dinitrophenol concentrations divert electrons from the extracellular electron pathway to an alternative electron sink. The present results open the door to the possible use of intact bacteria‐based photoelectrodes to develop technologies for sustainable biosensors with simultaneous environmental remediation. [ABSTRACT FROM AUTHOR]

The availability of agricultural wastewater in arid climes limits the possibility of exploiting purple non‐sulfur bacteria (PNSB) to recover aqua‐feed bioproducts. Thus, this study examines the feasibility of recovering such bioproducts using fuel‐synthesis process water (FSPW) as a feedstock. Experiments were performed under varying light conditions. The results revealed that PNSB cultured in the zero‐nitrogen feedstock had over 40 % protein content, contained substantial lipids and pigments, and reduced FSPW organics by over 70 %. The light intensity significantly impacted biomass constituents and treatment efficiency. The results are promising for the potential development of a circular economy to convert FSPW to aqua‐feed. [ABSTRACT FROM AUTHOR]

Phototrophic bacteria face diurnal variations of environmental conditions such as light and osmolarity that affect their carbon metabolism and ability to generate organic compounds. The model cyanobacterium, Synechocystis sp. PCC 6803 forms a biofilm when it encounters extreme conditions like high salt stress, but the molecular mechanisms involved in perception of environmental changes that lead to biofilm formation are unknown. Here, we studied two two‐component regulatory systems (TCSs) that contain diguanylate cyclases (DGCs), which produce the second messenger c‐di‐GMP, as potential components of the biofilm‐inducing signaling pathway in Synechocystis. Analysis of single mutants provided evidence for involvement of the response regulators, Rre2 and Rre8 in biofilm formation. A bacterial two‐hybrid assay showed that Rre2 and Rre8 each formed a TCS with a specific histidine kinase, Hik12 and Hik14, respectively. The in vitro assay showed that Rre2 had DGC activity regardless of its de/phosphorylation status, whereas Rre8 required phosphorylation for DGC activity. Hik14‐Rre8 likely functioned as an inducible sensing system in response to environmental change. Biofilm assays with Synechocystis mutants suggested that pairs of hik12‐rre2 and hik14‐rre8 responded to high salinity‐induced biofilm formation. Inactivation of hik12‐rre2 and hik14‐rre8 did not affect the performance of the light reactions of photosynthesis. These data suggest that Hik12‐Rre2 and Hik14‐Rre8 participate in biofilm formation in Synechocystis by regulating c‐di‐GMP production via the DGC activity of Rre2 and Rre8. [ABSTRACT FROM AUTHOR]

Tissue engineering strategies using cell‐laden constructs have shown promising results in the treatment of various types of damaged tissues. However, inadequate oxygen delivery to the macroscale 3D cell‐constructs for regenerating skeletal muscle tissue has remained a multiplex issue owing to the pivotal factors including cell metabolism and several regulatory intercellular pathways that eventually influence various cellular activities and determines cell phenotype. To overcome this issue, a photosynthetic cyanobacterium (Synechococcus elongatus) is employed in a methacrylated gelatin bioink. Furthermore, to effectively induce cell alignment in the bioink, in situ electric field stimulation is used in a bioprinting system to fabricate cell‐laden scaffolds for regenerating skeletal muscle tissue. Owing to the synergistic effects of the bioactive microenvironment that rescues cells from hypoxic conditions and activations of voltage‐gated ion channels, highly aligned, multi‐nucleated myofibers are obtained as well as significant upregulation (7–10‐fold) of myogenic‐related genes compared with conventionally prepared cell‐constructs. In addition, in vivo studies using a mouse volumetric muscle loss model demonstrate considerable restoration of muscle functionality and regeneration. [ABSTRACT FROM AUTHOR]

Purple phototrophic bacteria are one of the main actors in chemolithotrophic carbon fixation and, therefore, fundamental in the biogeochemical cycle. These microbes are capable of using insoluble electron donors such as ferrous minerals or even carbon‐based electrodes. Carbon fixation through extracellular electron uptake places purple phototrophic bacteria in the field of microbial electrosynthesis as key carbon capturing microorganisms. In this work we demonstrate biomass production dominated by purple phototrophic bacteria with a cathode (−0.6 V vs. Ag/AgCl) as electron donor. In addition, we compared the growth and microbial population structure with ferrous iron as the electron donor. We detect interaction between the cathode and the consortium showing a midpoint potential of 0.05 V (vs. Ag/AgCl). Microbial community analyses revealed different microbial communities depending on the electron donor, indicating different metabolic interactions. Electrochemical measurements together with population analyses point to Rhodopseudomonas genus as the key genus in the extracellular electron uptake. Furthermore, the genera Azospira and Azospirillum could play a role in the photoelectrotrophic consortium. [ABSTRACT FROM AUTHOR]

Phycobilisomes, the light‐harvesting complexes of cyanobacteria and red algae, are a resource for photosynthetic, photonic and fluorescence labeling elements. They cover an exceptionally broad spectral range, but the complex superstructure and assembly have been an obstacle. By replacing in Synechocystis sp. PCC 6803 the biliverdin reductases, we studied the role of chromophores in the assembly of the phycobilisome core. Introduction of the green‐absorbing phycoerythrobilin instead of the red‐absorbing phycocyanobilin inhibited aggregation. A novel, trimeric allophycocyanin (Dic‐APC) was obtained. In the small (110 kDa) unit, the two chromophores, phycoerythrobilin and phytochromobilin, cover a wide spectral range (550 to 660 nm). Due to efficient energy transfer, it provides an efficient artificial light‐harvesting element. Dic‐APC was generated in vitro by using the contained core‐linker, LC, for template‐assisted purification and assembly. Labeling the linker provides a method for targeting Dic‐APC. [ABSTRACT FROM AUTHOR]

Aerobic anoxygenic photoheterotrophic (AAP) bacteria represent a functional group of prokaryotic organisms that harvests light energy using bacteriochlorophyll‐containing photosynthetic reaction centers. They represent an active and rapidly growing component of freshwater bacterioplankton, with the highest numbers observed usually in summer. Species diversity of freshwater AAP bacteria has been studied before in lakes, but its seasonal dynamics remain unknown. In this report, we analysed temporal changes in the composition of the phototrophic community in an oligo‐mesotrophic freshwater lake using amplicon sequencing of the pufM marker gene. The AAP community was dominated by phototrophic Gammaproteobacteria and Alphaproteobacteria, with smaller contribution of phototrophic Chloroflexota and Gemmatimonadota. Phototrophic Eremiobacteriota or members of Myxococcota were not detected. Interestingly, some AAP taxa, such as Limnohabitans, Rhodoferax, Rhodobacterales or Rhizobiales, were permanently present over the sampling period, while others, such as Sphingomonadales, Rhodospirillales or Caulobacterales appeared only transiently. The environmental factors that best explain the seasonal changes in AAP community were temperature, concentrations of oxygen and dissolved organic matter. [ABSTRACT FROM AUTHOR]

Microbial communities play critical roles in fixing carbon from the atmosphere and fixing it in the soils. However, the large‐scale variations and drivers of these microbial communities remain poorly understood. Here, we conducted a large‐scale survey across China and found that soil autotrophic organisms are critical for explaining CO2 fluxes from the atmosphere to soils. In particular, we showed that large‐scale variations in CO2 fixation rates are highly correlated to those in autotrophic bacteria and phototrophic protists. Paddy soils, supporting a larger proportion of obligate bacterial and protist autotrophs, display four‐fold of CO2 fixation rates over upland and forest soils. Precipitation and pH, together with key ecological clusters of autotrophic microbes, also played important roles in controlling CO2 fixation. Our work provides a novel quantification on the contribution of terrestrial autotrophic microbes to soil CO2 fixation processes at a large scale, with implications for global carbon regulation under climate change. [ABSTRACT FROM AUTHOR]

The photosynthetic reaction center complex (RCC) of green sulfur bacteria (GSB) consists of the membrane‐imbedded RC core and the peripheric energy transmitting proteins called Fenna–Matthews–Olson (FMO). Functionally, FMO transfers the absorbed energy from a huge peripheral light‐harvesting antenna named chlorosome to the RC core where charge separation occurs. In vivo, one RC was found to bind two FMOs, however, the intact structure of RCC as well as the energy transfer mechanism within RCC remain to be clarified. Here we report a structure of intact RCC which contains a RC core and two FMO trimers from a thermophilic green sulfur bacterium Chlorobaculum tepidum at 2.9 Å resolution by cryo‐electron microscopy. The second FMO trimer is attached at the cytoplasmic side asymmetrically relative to the first FMO trimer reported previously. We also observed two new subunits (PscE and PscF) and the N‐terminal transmembrane domain of a cytochrome‐containing subunit (PscC) in the structure. These two novel subunits possibly function to facilitate the binding of FMOs to RC core and to stabilize the whole complex. A new bacteriochlorophyll (numbered as 816) was identified at the interspace between PscF and PscA‐1, causing an asymmetrical energy transfer from the two FMO trimers to RC core. Based on the structure, we propose an energy transfer network within this photosynthetic apparatus. [ABSTRACT FROM AUTHOR]

Sharing structural and mechanistic properties with the dinitrogen‐fixing enzyme nitrogenase, dark‐operative protochlorophyllide oxidoreductase (DPOR) participates in the biosynthesis of bacteriochlorophyll, subsequently enabling photosynthesis by photosynthetic bacteria. In contrast to the light‐dependent POR, electron transfer in DPOR is coupled to the hydrolysis of adenosine triphosphate for the two‐electron stereoselective reduction of protochlorophyllide (Pchlide) to chlorophyllide (Chlide), a coupling also employed by nitrogenases for the multielectron reduction of dinitrogen to ammonia. The importance of adenosine triphosphate hydrolysis is not fully understood for these enzymes, and electrochemistry is a valuable technique to regulate and/or monitor electron delivery to these enzymes. Here, we report three alternative electron donors that support protochlorophyllide reduction in the DPOR system, which could also enable electroenzymatic studies of DPOR. We demonstrate the turnover of DPOR within a spectroelectrochemical configuration, permitting the formation of Chlide to be followed and coupled to electron utilization by DPOR. [ABSTRACT FROM AUTHOR]

Control phenomena in biology usually refer to changes in gene expression and protein translation and modification. In this paper, another mode of regulation is highlighted; we propose that photosynthetic organisms can harness the interplay between localization and delocalization of energy transfer by utilizing small conformational changes in the structure of light‐harvesting complexes. We examine the mechanism of energy transfer in photosynthetic pigment‐protein complexes, first through the scope of theoretical work and then by in vitro studies of these complexes. Next, the biological relevance to evolutionary fitness of this localization‐delocalization switch is explored by in vivo experiments on desert crust and marine cyanobacteria, which are both exposed to rapidly changing environmental conditions. These examples demonstrate the flexibility and low energy cost of this mechanism, making it a competitive survival strategy. [ABSTRACT FROM AUTHOR]

An efficient and rapid energy transfer (ET) mechanism is theoretically proposed only by mimicking the circular structure of natural photosynthetic light‐harvesting (LH) antennae, without spatial and energetic disorders as in natural photosynthetic systems. Two B850 LH complexes of photosynthetic bacterium are adopted, and it is shown that for close LH antennae the ET rate can be optimized by functionally separating ET from photon absorption within exciton energy levels by an adjustment of the distance between the LH antennae at room temperature. As a result, for close LHs, the two processes of photon absorption and ET can be energetically and functionally divided within the same exciton energy level. From the analysis of the temperature dependence of transfer rate, it is also shown that the two energetically separated processes are connected by thermal pumping of the exciton population and an optimized ET rate can be achieved at room temperature when the energy difference between optically allowed and forbidden states is comparable with the thermal energy of the environment. [ABSTRACT FROM AUTHOR]

Carotenoids are increasingly used in food and medical industry. However, the instability of carotenoids restricted its application. The stability of carotenoids extracts from a marine photosynthetic bacterium, Ectothiorhodospira shaposhnikovii P2, was studied under different storage conditions including light and dark, temperature (4–60°C), pH range (4.0–10.0), and three metallic solutions (Na+, Mg2+, & Fe3+). The results showed that carotenoids were suitable to store at dark, low temperature, and neutral‐to‐alkali conditions. At the presence of metals, including Na+, Mg2+, and Fe3+, carotenoids decreased differently. Especially, Fe3+ could seriously decrease the carotenoids concentration. The research could provide a reference for storage of natural pigments, especially carotenoids from photosynthetic bacteria. Novelty impact statement: The stability of carotenoids extracts from a marine photosynthetic bacterium, Ectothiorhodospira shaposhnikovii P2, was studied under different storage conditions.The present research work showed that carotenoids from marine photosynthetic bacterium P2 were suitable for storage in dark, low temperature, neutral‐to‐alkaline medium.In the presence of metallic solutions, including Na+, Mg2+, and Fe3+, carotenoids decreased differently. [ABSTRACT FROM AUTHOR]

Microbial consortia consisting of phototrophs and heterotrophs have raised extensive attention due to their potential in sustainable biotechnology. The challenge remains in the selection of appropriate partners since most heterotrophic microorganisms cannot naturally use the intermediate carbohydrates secreted by autotrophic partners. In a recent study, the Ni Lab has developed a highly compatible autotrophic‐heterotrophic symbiotic system comprising Synechococcus elongatus and Vibrio natriegens. V. natriegens (the sucrose utilization module) shows a high degree of nutritional complementarity and culturing compatibility with the engineered S. elongatus (the CO2 sequestration module). The combination of both species channels CO2 into various valuable chemicals, enabling carbon‐negative biosynthesis. [ABSTRACT FROM AUTHOR]

In present research work, isolation of the biopolymer, from the novel strain of phototrophic anoxygenic phototrophic bacteria Rhodopseudomonas palustris isolated from sugar industrial effluent, is reported. It is characterized and the efficacy of binding the biopolymer (PHB) with protein (BSA) is investigated. The strain Rp. KRPR02 is selected for the characterization and protein binding studies as it produced more amounts of PHB. The extracted biopolymer is confirmed as PHB by instrumental techniques such as UV–Visible spectroscopy, FTIR analysis, C13 NMR spectroscopy, and XRD analysis. The efficiency of PHB binding to BSA is evaluated and found that it can efficiently bind to BSA. Hence, it can be used for biomedical and pharmaceutical applications as drug carriers and also as nanocapsules to carry the micro‐ and macronutrients in agriculture. [ABSTRACT FROM AUTHOR]

In coastal China, the clam–shrimp polyculture system is a new model of seawater aquaculture. A 60‐day rearing experiment was performed to evaluate the effects of commercial effective microorganisms (EM) bacteria liquid, containing bacillus, photosynthetic bacteria and lactic acid bacteria and mechanical aeration on water quality and their growth performance and antioxidant status. A 2 × 2 layout was designed, including four treatment groups were abbreviated as O (non‐supplementation of EM bacteria liquid and no mechanical aeration), A (supplementation of EM bacteria liquid), B (mechanical aeration) and AB (supplementation of EM bacteria liquid and mechanical aeration). AB group had significantly lower concentration of ammonia, nitrite, nitrate, total inorganic nitrogen (TIN), total inorganic phosphorus (TIP) and chemical oxygen demand (CODMn) than O group (p < 0.05) on the 60th day. Clams and shrimps farmed in the interaction group (AB group) had significantly higher body weight than O group on the 60th day (p < 0.05). Furthermore, body weight of clams had no significant differences between single factor groups (A and B groups) and O group (p > 0.05), while shrimps had significantly higher body weight in single factor groups (A and B groups) than O group on the 60th day (p < 0.05). Weight gain and specific growth rate of clams had no significant differences among different groups at the same time (p > 0.05). Shrimps reared in B and AB groups showed significantly higher T‐SOD activities, T‐AOC and CAT activities than those reared in O and A groups (p < 0.05). There were significantly lower MDA activities in B and AB groups than O group (p < 0.05), while no significant difference was observed in hepatic MDA activities in A group than other groups (p > 0.05). There were no significant differences in T‐SOD activities of clams between the four groups (p > 0.05). Clams farmed in AB group had lower MDA activities than other groups (p < 0.05). Clams farmed in AB group had significantly higher T‐AOC activities than O and B groups (p < 0.05). Although B group in T‐AOC activities was significantly lower than A group (p < 0.05), it had no significant difference than O group (p > 0.05). Finally, clams farmed in A and AB groups had significantly higher CAT activities than O group (p < 0.05), while they had no significant difference than B group (p > 0.05). In conclusion, single EM bacteria addition or mechanical aeration had limited function in improving water quality, growth performance and antioxidant capacity of clams and shrimps. In contrast, the interactive impact of adding EM bacteria and mechanical aeration could be competent for this task. Therefore, combined adding EM bacteria and mechanical aeration should be an effective way to improve water quality and their growth performance and immune function in the clam–shrimp polyculture system. [ABSTRACT FROM AUTHOR]

The organic polymer lignin is a component of plant cell walls, which like (hemi)‐cellulose is highly abundant in nature and relatively resistant to degradation. However, extracellular enzymes released by natural microbial consortia can cleave the β‐aryl ether linkages in lignin, releasing monoaromatic phenylpropanoids that can be further catabolised by diverse species of bacteria. Biodegradation of lignin is therefore important in global carbon cycling, and its natural abundance also makes it an attractive biotechnological feedstock for the industrial production of commodity chemicals. Whilst the pathways for degradation of lignin‐derived aromatics have been extensively characterised, much less is understood about how they are recognised and taken up from the environment. The purple phototrophic bacterium Rhodopseudomonas palustris can grow on a range of phenylpropanoid monomers and is a model organism for studying their uptake and breakdown. R. palustris encodes a tripartite ATP‐independent periplasmic (TRAP) transporter (TarPQM) linked to genes encoding phenylpropanoid‐degrading enzymes. The periplasmic solute‐binding protein component of this transporter, TarP, has previously been shown to bind aromatic substrates. Here, we determine the high‐resolution crystal structure of TarP from R. palustris as well as the structures of homologous proteins from the salt marsh bacterium Sagittula stellata and the halophile Chromohalobacter salexigens, which also grow on lignin‐derived aromatics. In combination with tryptophan fluorescence ligand‐binding assays, our ligand‐bound co‐crystal structures reveal the molecular basis for high‐affinity recognition of phenylpropanoids by these TRAP transporters, which have potential for improving uptake of these compounds for biotechnological transformations of lignin. [ABSTRACT FROM AUTHOR]

The interactions of chlorophyll (Chl) and bacteriochlorophyll (BChl) pigments with the polypeptides in photosynthetic light‐harvesting proteins are responsible for controlling the absorption energy of (B)Chls in protein matrixes. The binding pocket of B800 BChl a in LH2 proteins, which are peripheral light‐harvesting proteins in purple photosynthetic bacteria, is useful for studying such structure–property relationships. We report the reconstitution of Chl f, which has the formyl group at the 2‐position, in the B800 cavity of LH2 from the purple bacterium Rhodoblastus acidophilus. The Qy absorption band of Chl f in the B800 cavity was shifted by 14 nm to longer wavelength compared to that of the corresponding five‐coordinated monomer in acetone. This redshift was larger than that of Chl a and Chl b. Resonance Raman spectroscopy indicated hydrogen bonding between the 2‐formyl group of Chl f and the LH2 polypeptide. These results suggest that this hydrogen bonding contributes to the Qy redshift of Chl f. Furthermore, the Qy redshift of Chl f in the B800 cavity was smaller than that of Chl d. This may have arisen from the different patterns of hydrogen bonding between Chl f and Chl d and/or from the steric hindrance of the 3‐vinyl group in Chl f. [ABSTRACT FROM AUTHOR]

Summary: Halorhodospira halophila, one of the most‐xerophilic halophiles, inhabits biophysically stressful and energetically expensive, salt‐saturated alkaline brines. Here, we report an additional stress factor that is biotic: a diminutive Candidate‐Phyla‐Radiation bacterium, that we named 'Ca. Absconditicoccus praedator' M39‐6, which predates H. halophila M39‐5, an obligately photosynthetic, anaerobic purple‐sulfur bacterium. We cultivated this association (isolated from the hypersaline alkaline Lake Hotontyn Nur, Mongolia) and characterized their biology. 'Ca. Absconditicoccus praedator' is the first stably cultivated species from the candidate class‐level lineage Gracilibacteria (order‐level lineage Absconditabacterales). Its closed‐and‐curated genome lacks genes for the glycolytic, pentose phosphate‐ and Entner–Doudoroff pathways which would generate energy/reducing equivalents and produce central carbon currencies. Therefore, 'Ca. Absconditicoccus praedator' is dependent on host‐derived building blocks for nucleic acid‐, protein‐, and peptidoglycan synthesis. It shares traits with (the uncultured) 'Ca. Vampirococcus lugosii', which is also of the Gracilibacteria lineage. These are obligate parasitic lifestyle, feeding on photosynthetic anoxygenic Gammaproteobacteria, and absorption of host cytoplasm. Commonalities in their genomic composition and structure suggest that the entire Absconditabacterales lineage consists of predatory species which act to cull the populations of their respective host bacteria. Cultivation of vampire : host associations can shed light on unresolved aspects of their metabolism and ecosystem dynamics at life‐limiting extremes. [ABSTRACT FROM AUTHOR]

BACKGROUND: GroEL, which is a chaperone, plays a key role in maintaining protein homeostasis and, among other functions, serves to prevent protein misfolding and aggregation. In addition, the GroEL protein also has a significant effect on enhancing plant resistance and inhibiting plant diseases. However, the function of the GroEL protein in the inhibition of rice blast remains unknown. RESULTS: Field experiment results show that photosynthetic bacteria PSB‐06 have a good control effect on Magnaporthe oryzae. PSB‐06 also can promote rice growth and enhance stress resistance. A GroEL protein which was separated and purified from photosynthetic bacteria had a significant antagonistic effect on appressorial formation and pathogenicity of Magnaporthe oryzae, meanwhile transcriptional analysis demonstrated that the GroEL protein could improve the expression of defense gene of rice. CONCLUSION: Our results show that the photosynthetic bacteria Rhodopseudomonas palustris significantly controls rice blast disease. Its action involves an extracellular GroEL protein, which inhibits appressoria formation, antagonizes the pathogenicity of Magnaporthe oryzae and promotes a host defense response. The research results provide evidence of the potential of this photosynthetic bacterium as a biocontrol agent at least for rice blast control. © 2021 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Summary: Purple non‐sulfur photosynthetic bacteria (PNSB) such as Rhodobacter capsulatus serve as a versatile platform for fundamental studies and various biotechnological applications. In this study, we sought to develop the class II RNA‐guided CRISPR/Cas12a system from Francisella novicida for genome editing and transcriptional regulation in R. capsulatus. Template‐free disruption method mediated by CRISPR/Cas12a reached ˜ 90% editing efficiency when targeting ccoO or nifH gene. When both genes were simultaneously edited, the multiplex editing efficiency reached > 63%. In addition, CRISPR interference (CRISPRi) using deactivated Cas12a was also evaluated using reporter genes egfp and lacZ, and the transcriptional repression efficiency reached ˜ 80%. In summary, our work represents the first report to develop CRISPR/Cas12a‐mediated genome editing and transcriptional regulation in R. capsulatus, which would greatly accelerate PNSB‐related researches. [ABSTRACT FROM AUTHOR]

Photoactive biohybrid soft nanoparticles are obtained by embedding the Rhodobacter sphaeroides Reaction Center (RC) in polydopamine (PDA) suspended aggregates and treating them with ethylenediamine (EDA). Such PDA:EDA@RC nanoparticles are investigated for photocurrent generation in photoelectrochemical cells, which are able to convert sunlight into electrical energy. The photosynthetic protein retains its structural and functional integrity in the nanostructures and the PDA:EDA@RC nanoparticles exhibit better water dispersity, improved light collection ability, and higher photocurrent generation compared to the PDA@RC precursors, where the reaction center is embedded in pure PDA. The hybrid soft nanoparticles incorporating the RC bacterial photoenzyme show charge separated state generation comparable to that of the pristine enzyme in solution, overcoming the main limitation of RC encapsulation in pure PDA, which is the polymer low light transmission ability. As a consequence, photocurrents obtained by RC within the PDA:EDA environment are almost doubled with respect to the PDA@RC. The biohybrid composites described here represent an interesting example of effective functional nanostructures for sunlight photoconversion based on a biological component addressed in a tunable biocompatible polymer composite, also showing the potential of fine chemical tailoring of polydopamine biointerfaces. [ABSTRACT FROM AUTHOR]

Microalgae, a kind of conventional bait for bivalves, can increase the cost of shellfish aquaculture. On this basis, Ruditapes philippinarum spat was selected to evaluate the feasibility of using photosynthetic bacteria (PSB) and marine yeasts as microalgae substitutes. The results showed that the addition of bacteria obviously affected the growth status of spat. Firstly, the survival rate of spat in 5%, 40%, 50% and 70% PSB substitution groups as well as 5% and 40% yeast substitution groups was not significantly different from that in microalgae group (p > 0.05), but that in other substitution groups was significantly lower than that in microalgae group (p < 0.05). Secondly, the growth rate of spat in PSB substitution groups (except for the 10% PSB substitution group) was significantly higher than that in microalgae group, and the 5% PSB substitution group had a growth rate which was 109.55% higher than that in microalgae group. There was no significant difference in the growth rate between microalgae group and 10%, 40%, 50% and 70% yeast substitution groups. Thirdly, the addition of bacteria also affected the digestive ability of shellfish. Pepsin enzyme activity in 20% PSB substitution group was 29.85% higher than that in microalgae group. Moreover, 5% and 40% yeast substitution groups had no significant difference in the pepsin enzyme activity compared with microalgae group. Finally, the nitrogen (N) and phosphorus (P) concentrations in the bacteria addition treatments were higher than those in the control treatment at the end of the experiment, but they were generally maintained at lower levels. In conclusion, it is feasible to partially replace microalgae with PSB and marine yeasts, and it is suggested that shellfish culture should be combined with wastewater utilization to promote the healthy development of aquaculture industry. [ABSTRACT FROM AUTHOR]

Although pulse amplitude modulation (PAM) fluorometry has revolutionized photosynthetic studies, Photosynthetic Electron Transport Rate (ETR) cannot be measured using PAM technology in some organisms. We compare in vivo absorbance information on a selection of photosynthetic organisms using an integrating sphere spectrophotometry on a variety of oxygenic and nonoxygenic photo‐organisms and provide fluorescence data to help in understanding why PAM technology is unsuccessful on some organisms, particularly cyanobacteria. The study includes anoxygenic photosynthetic bacteria: Afifella marina, Rhodopseudomonas palustris and Thermochromatium which are all RC‐2 type photosynthetic bacteria (Bacteriochlorophyll a or BChl a) which are known to have measureable delayed fluorescence, Yield and hence measureable ETR. The common unicellular green alga, Chlorella sp (Chl a + b) uses the same primary photosynthetic pigments as vascular plants. Comparisons are made to some other representative oxygenic unicellular organisms: Trebouxia (Chlorophyta, Chl a + b), Chaetoceros (a diatom, Chl a + c1c2) and the unusual cyanobacterium Acaryochloris marina which has Chl d + a but uses Chl d as its primary photosynthetic pigment. Synechococcus R‐2 (Cyanobacteria) has only Chl a. Its fluorescence is outside the range normally used for measuring photosynthesis using PAM technology: delayed fluorescence is not readily detectable. [ABSTRACT FROM AUTHOR]

Mono Lake is a closed‐basin, hypersaline, alkaline lake located in Eastern Sierra Nevada, California, that is dominated by microbial life. This unique ecosystem offers a natural laboratory for probing microbial community responses to environmental change. In 2017, a heavy snowpack and subsequent runoff led Mono Lake to transition from annually mixed (monomictic) to indefinitely stratified (meromictic). We followed microbial succession during this limnological shift, establishing a two‐year (2017–2018) water‐column time series of geochemical and microbiological data. Following meromictic conditions, anoxia persisted below the chemocline and reduced compounds such as sulfide and ammonium increased in concentration from near 0 to ~400 and ~150 µM, respectively, throughout 2018. We observed significant microbial succession, with trends varying by water depth. In the epilimnion (above the chemocline), aerobic heterotrophs were displaced by phototrophic genera when a large bloom of cyanobacteria appeared in fall 2018. Bacteria in the hypolimnion (below the chemocline) had a delayed, but systematic, response reflecting colonization by sediment "seed bank" communities. Phototrophic sulfide‐oxidizing bacteria appeared first in summer 2017, followed by microbes associated with anaerobic fermentation in spring 2018, and eventually sulfate‐reducing taxa by fall 2018. This slow shift indicated that multi‐year meromixis was required to establish a sulfate‐reducing community in Mono Lake, although sulfide oxidizers thrive throughout mixing regimes. The abundant green alga Picocystis remained the dominant primary producer during the meromixis event, abundant throughout the water column including in the hypolimnion despite the absence of light and prevalence of sulfide. Our study adds to the growing literature describing microbial resistance and resilience during lake mixing events related to climatic events and environmental change. [ABSTRACT FROM AUTHOR]

Anoxygenic phototrophic bacteria (APB) are a very significant metabolic functional group in the phytotelmata of tank‐forming Bromeliaceae plants. Considering the close relationships existing between the bromeliad and its tank microbiota, the dominance of APB raises the question of their role in the ecology and evolution of these plants.Here, using pufM gene sequencing for taxonomic profiling, we investigated the structure of APB communities in the tanks of five bromeliad species exhibiting different habitat characteristics (i.e. physicochemical factors associated with the host), and occurring in different localities of French Guiana.We found that APB assemblages were specific to plant species and were less dependent on location or on bromeliad habitat characteristics. This convergence suggests that the identity of the bromeliad species per se is more important than habitat filtering or dispersal to control specific assembly rules for APB.The pufM OTUs were affiliated with five orders of Alpha‐ and Beta‐proteobacteria (Rhodobacterales, Sphingomonadales, Rhizobiales, Burkholderiales and Rhodospirillales), and we assume that they may be major components of the core microbiota of plant‐held waters.Our findings also revealed that up to 79% of the sequences were affiliated with APB clades possessing nitrogen‐fixing genes suggesting that this metabolic capability is widespread within the APB community inhabiting tank bromeliads. We hypothesized that bromeliads may benefit nutritionally from associations with free‐living APB capable to fix atmospheric nitrogen.Synthesis. Understanding the dominance of APB in tank bromeliads and determining whether a potential interplay exists between these partners is an intriguing aspect of possible mutualistic and coevolving interactions between the two existing forms of chlorophototrophy (i.e. bacteriochlorophyll‐based anoxygenic and chlorophyll‐based oxygenic phototrophy). In the present study, we found that bromeliad species was the main factor that explained variance in APB community composition. These findings suggest that APB and tank bromeliads may have a close, mutualistic relationship and we hypothesize according to our genomic analyses that APB may promote the bromeliad growth by provisioning essential nutrients like nitrogen. [ABSTRACT FROM AUTHOR]

Summary: Several significant ecosystem services are performed by biological soil crusts (BSCs) in drylands, wherein photoautotrophic microorganisms are commonly critical contributors. However, aerobic anoxygenic phototrophic bacteria (AAnPB) are rarely reported in BSCs, despite being the second major branch of Earth's phototrophic microbes. Here, we collected different types of BSCs and their subsoils from temperate deserts, investigated distributions of AAnPB communities among BSCs using cultivation and high‐throughput sequencing approaches, predicted keystone species by co‐occurrence network analysis, and verified their effects on BSCs formation through microcosm experiments. The absolute abundances and diversity of AAnPB were higher in BSCs and were closely related with BSCs successional stages, as well as soil organic carbon contents. AAnPB communities in both BSCs and their subsoils were dominated by Proteobacteria and Alphaproteobacteria, specifically Acetobacteraceae, Rhodospirillaceae, Roseiflexaceae, Sphingomonadaceae and Caulobacteraceae families. Mean annual precipitation, pH and available nutrients were the primary factors that shaped AAnPB community structures. The predicted keystone species belonged to the families Acetobacteraceae, Rhodospirillaceae and Sphingomonadanceae. Microcosm experiments demonstrated that inoculation with strains from the three families greatly accelerated the formation and development of BSCs. These observations suggest that AAnPB are likely important functional groups in BSCs that significantly contribute to their formation and important ecosystem services. [ABSTRACT FROM AUTHOR]

BACKGROUND Anaerobic treatments based on purple phototrophic bacteria (PPB) can be a more efficient and less energetically demanding alternative to aerobic biological processes currently used in refinery and petrochemistry wastewater (RPWW) treatment plants. Toxic compounds in the RPWW might compromise PPB metabolism, limiting its feasibility. In this work, seven toxic compounds that are typical components of RPWW [benzene, toluene, ethylbenzene, o‐xylene (BTEX), furfural, methyl‐di‐ethanolamine (MDEA) and butanone] were evaluated as potential inhibitors of the specific activity and growth of PPB. RESULTS: Inhibitory Ki parameters of 50% reduction of specific activity or biomass yield were calculated. Most of the BTEX compounds showed initial inhibitory effects on the specific activity, with Ki values of 305 ± 9, 151 ± 17 and 84 ± 2 mg L−1 for benzene, toluene and ethylbenzene, respectively. These compounds also caused inhibition of PPB growth (Ki of 411 ± 7 and 241 ± 3 mg L−1, 26% below the control, respectively). By contrast, o‐xylene affected neither the activity nor the growth. Furfural inhibited the initial specific activity (Ki of 448 ± 24 mg L−1), with no effect over the PPB growth. However, MDEA and butanone improved the initial specific activity of PPB (15% and 40% above the control, respectively). However, butanone negatively impacted the growth which decreased to ≤40% below the control. CONCLUSIONS: Calculated inhibition thresholds for the seven toxic compounds were far above the actual concentrations found in the RPWW. Thus, anaerobic treatments based on PPB for the treatment of RPWW would not be limited by the presence of the toxic compounds studied here. © 2021 Society of Chemical Industry (SCI). [ABSTRACT FROM AUTHOR]

Summary: The transition from an engulfed autonomous unicellular photosynthetic bacterium to a semiautonomous endosymbiont plastid was accompanied by the transfer of genetic material from the endosymbiont to the nuclear genome of the host, followed by the establishment of plastid‐to‐nucleus (retrograde) signaling. The retrograde coordinated activities of the two subcellular genomes ensure chloroplast biogenesis and function as the photosynthetic hub and sensing and signaling center that tailors growth‐regulating and adaptive processes. This review specifically focuses on the current knowledge of selected stress‐induced retrograde signals, genomes uncoupled 1 (GUN1), methylerythritol cyclodiphosphate (MEcPP), apocarotenoid and β‐cyclocitral, and 3′‐phosphoadenosine 5′‐phosphate (PAP), which evolved to establish the photoautotrophic lifestyle and are instrumental in the integration of light and hormonal signaling networks to ultimately fashion adaptive responses in an ever‐changing environment. [ABSTRACT FROM AUTHOR]

Summary: Marine photosynthetic microalgae are ubiquitously associated with bacteria in nature. However, the influence of these bacteria on algal cultures in bioreactors is still largely unknown. In this study, eighteen different bacterial strains were isolated from cultures of Nannochloropsis sp. CCAP211/78 in two outdoor pilot‐scale tubular photobioreactors. The majority of isolates was affiliated with the classes Alphaproteobacteria and Flavobacteriia. To assess the impact of the eighteen strains on the growth of Nannochloropsis sp. CCAP211/78, 24‐well plates coupled with custom‐made LED boxes were used to simultaneously compare replicate axenic microalgal cultures with addition of individual bacterial isolates. Co‐culturing of Nannochloropsis sp. CCAP211/78 with these strains demonstrated distinct responses, which shows that the technique we developed is an efficient method for screening the influence of harmful/beneficial bacteria. Two of the tested strains, namely a strain of Maritalea porphyrae (DMSP31) and a Labrenzia aggregata strain (YP26), significantly enhanced microalgal growth with a 14% and 12% increase of the chlorophyll concentration, respectively, whereas flavobacterial strain YP206 greatly inhibited the growth of the microalga with 28% reduction of the chlorophyll concentration. Our study suggests that algal production systems represent a 'natural' source to isolate and study microorganisms that can either benefit or harm algal cultures. [ABSTRACT FROM AUTHOR]

Purple phototrophic bacteria (PPB) showed an enormous potential for polyhydroxyalkanoates (PHA) production using the hydrolysate from lignocellulosic waste as feedstock. Thermal hydrolysis pretreatment was carried out at three different temperatures (120, 150, and 180°C) aiming to improve the biodegradability of the lignocellulosic waste. After this pretreatment, two streams are collected: a solid and a liquid fraction. The anaerobic digestion process of the pretreated solid fraction at 180°C increased its biodegradability extent by 31% compared to the untreated biomass, yielding 210 ± 10 L CH4 kg−1 VS even when the liquid fraction was removed. On the photoheterotrophic of the liquid fraction, PPB were able to remove up to 55% of COD during batch operation, showing peaks of PHA production yield up to 21 wt.%. The treatment of the liquid fraction obtained at high temperatures (T ˃ 120°C) reduces biomass growth and COD consumption efficiency, and thus potential productivity, with no effect over the specific activity and the biomass yield, indicating growth limitation by lack of nutrients (N and P). A preliminary economical assessment indicates suitable economic viability based on an energetic autarchy process. This study pioneered a PPB‐based biorefinery for PHA production from lignocellulosic residues and aligned within the bioeconomy strategy of the European Union. [ABSTRACT FROM AUTHOR]

BACKGROUND: Animal manure frequently harbors pathogenic microorganisms such as Salmonella spp. and diarrheagenic Escherichia coli. A defined microbial consortium such as effective microorganisms (EM) can potentially be used as a biocontrol against manure‐borne human pathogens such as Salmonella and pathogenic E. coli. The objective of the study was to investigate the efficacy of EM to decontaminate cattle manure. RESULTS: EM was first characterized by enumeration and identification of lactic acid bacteria (LAB), yeasts, actinomycetes and phototrophic bacteria (PB). The population density of LAB, yeasts, actinomycetes and presumptive PB was 6.9, 5.2, 5.9 and 3.9 log CFU g−1 respectively. LAB and yeast isolates were molecularly confirmed as Lactobacillus plantarum and L. casei (LAB) and Yarrowia lipolytica, Rhodotorula mucilaginosa and Picha manshurica (yeasts) respectively. Culture‐independent molecular analysis revealed the presence of additional species including L. parabuchneri and Enterococcus faecium (LAB) and bacterial spore‐formers Bacillus cereus and Clostridium spp. Application of EM to fresh cattle manure, inoculated with ~5–6 log CFU g−1 of antibiotic‐resistant strain of indicator organism E. coli ATCC 25922, resulted in complete elimination of the organism in 20 days, while survivors were still detected in the untreated counterpart. CONCLUSION: EM can potentially be used for sustainable pathogen control in cattle manure for enhanced food safety and environmental health. © 2020 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Lake Bonney (McMurdo Dry Valleys, east Antarctica) represents a year‐round refugium for life adapted to permanent extreme conditions. Despite intensive research since the 1960s, due to the logistical constraints posed by 4‐months of 24‐h darkness, knowledge of how the resident photosynthetic microorganisms respond to the polar winter is limited. In addition, the lake level has risen by more than 3 m since 2004: impacts of rapid lake level rise on phytoplankton community structure is also poorly understood. From 2004 to 2015 an in situ submersible spectrofluorometer (bbe FluoroProbe) was deployed in Lake Bonney during the austral summer to quantify the vertical structure of four functional algal groups (green algae, mixed algae, and cryptophytes, cyanobacteria). During the 2013–2014 field season the Fluoroprobe was mounted on autonomous cable‐crawling profilers deployed in both the east and west lobes of Lake Bonney, obtaining the first daily phytoplankton profiles through the polar night. Our findings showed that phytoplankton communities were differentially impacted by physical and chemical factors over long‐term versus seasonal time scales. Following a summer of rapid lake level rise (2010–2011), an increase in depth integrated chlorophyll a (chl‐a) occurred in Lake Bonney caused by stimulation of photoautotrophic green algae. Conversely, peaks in chl‐a during the polar night were associated with an increase in mixotrophic haptophytes and cryptophytes. Collectively our data reveal that phytoplankton groups possessing variable trophic abilities are differentially competitive during seasonal and long‐term time scales owing to periods of higher nutrients (photoautotrophs) versus light/energy limitation (mixotrophs). Key Points: A profiling fluorometer collected the first over‐winter daily phytoplankton profilesPhytoplankton communities were differentially impacted by physical and chemical factors over long‐term versus seasonal time scalesPhyoplankton groups are differentially competitive due to periods of higher nutrients versus light/energy limitation [ABSTRACT FROM AUTHOR]

Summary: A plant‐associated phototrophic bacterium, R. palustris strain PS3, was inoculated into a soil‐based MFC to generate electricity. We evaluated the performance of this soil‐based microbial fuel cell (MFC) and elucidated the essential factors that contributed to power generation. PS3 showed the potential to enhance power generation, especially when the apparatus was operated in a sealed chamber with illumination. We deduced that the improved power performance was due to the enhanced electron transport through the living electrode that was grown as a PS3 biofilm via photoheterotrophic metabolism. In addition, we suggested that the interplay between phototrophic fixation of ambient CO2 and anaerobic oxidation of ferrous iron in soil was also involved in the increased power output. We implemented CMOS (complementary metal‐oxide‐semiconductor) technology with the soil‐based MFC to harvest energy in a more efficient and stable manner. The above system is expected to provide a potentially low‐cost and low‐energy system with a high power conversion efficiency for practical applications in the future. [ABSTRACT FROM AUTHOR]

Summary: Microbialites are usually carbonate‐rich sedimentary rocks formed by the interplay of phylogenetically and metabolically complex microbial communities with their physicochemical environment. Yet, the biotic and abiotic determinants of microbialite formation remain poorly constrained. Here, we analysed the structure of prokaryotic and eukaryotic communities associated with microbialites occurring in several crater lakes of the Trans‐Mexican volcanic belt along an alkalinity gradient. Microbialite size and community structure correlated with lake physicochemical parameters, notably alkalinity. Although microbial community composition varied across lake microbialites, major taxa‐associated functions appeared quite stable with both, oxygenic and anoxygenic photosynthesis and, to less extent, sulphate reduction, as major putative carbonatogenic processes. Despite interlake microbialite community differences, we identified a microbial core of 247 operational taxonomic units conserved across lake microbialites, suggesting a prominent ecological role in microbialite formation. This core mostly encompassed Cyanobacteria and their typical associated taxa (Bacteroidetes, Planctomycetes) and diverse anoxygenic photosynthetic bacteria, notably Chloroflexi, Alphaproteobacteria (Rhodobacteriales, Rhodospirilalles), Gammaproteobacteria (Chromatiaceae) and minor proportions of Chlorobi. The conserved core represented up to 40% (relative abundance) of the total community in lakes Alchichica and Atexcac, displaying the highest alkalinities and the most conspicuous microbialites. Core microbialite communities associated with carbonatogenesis might be relevant for inorganic carbon sequestration purposes. [ABSTRACT FROM AUTHOR]

Summary: The cyanobacterium Synechococcus elongatus (SE) has been shown to rescue ischaemic heart muscle after myocardial infarction by photosynthetic oxygen production. Here, we investigated SE toxicity and hypothesized that systemic SE exposure does not elicit a significant immune response in rats. Wistar rats intravenously received SE (n = 12), sterile saline (n = 12) or E. coli lipopolysaccharide (LPS, n = 4), and a subset (8 SE, 8 saline) received a repeat injection 4 weeks later. At baseline, 4 h, 24 h, 48 h, 8 days and 4 weeks after injection, clinical assessments, blood cultures, blood counts, lymphocyte phenotypes, liver function tests, proinflammatory cytokines and immunoglobulins were assessed. Across all metrics, SE rats responded comparably to saline controls, displaying no clinically significant immune response. As expected, LPS rats exhibited severe immunological responses. Systemic SE administration does not induce sepsis or toxicity in rats, thereby supporting the safety of cyanobacteria–mammalian symbiotic therapeutics using this organism. [ABSTRACT FROM AUTHOR]

Summary: Photosynthetic bacteria are abundant in alkaline, terrestrial hot springs and there is a long history of research on phototrophs in Yellowstone National Park (YNP). Hot springs provide a framework to examine the ecophysiology of phototrophs in situ because they provide natural gradients of geochemistry, pH and temperature. Phototrophs within the Cyanobacteria and Chloroflexi groups are frequently observed in alkaline hot springs. Decades of research has determined that temperature constrains Cyanobacteria in alkaline hot springs, but factors that constrain the distribution of phototrophic Chloroflexi remain unresolved. Using a combination of 16S rRNA gene sequencing and photoassimilation microcosms, we tested the hypothesis that temperature would constrain the activity and composition of phototrophic Cyanobacteria and Chloroflexi. We expected diversity and rates of photoassimilation to decrease with increasing temperature. We report 16S rRNA amplicon sequencing along with carbon isotope signatures and photoassimilation from 45 to 72°C in two alkaline hot springs. We find that Roseiflexus, Chloroflexus (Chloroflexi) and Leptococcus (Cyanobacteria) operational taxonomic units (OTUs) have distinct distributions with temperature. This distribution suggests that, like phototrophic Cyanobacteria, temperature selects for specific phototrophic Chloroflexi taxa. The richness of phototrophic Cyanobacteria decreased with increasing temperature along with a decrease in oxygenic photosynthesis, whereas Chloroflexi richness and rates of anoxygenic photosynthesis did not decrease with increasing temperature, even at temperatures approaching the upper limit of photosynthesis (~72–73°C). Our carbon isotopic data suggest an increasing prevalence of the 3‐hydroxypropionate pathway with decreasing temperature coincident with photoautotrophic Chloroflexi. Together these results indicate temperature plays a role in defining the niche space of phototrophic Chloroflexi (as has been observed for Cyanobacteria), but other factors such as morphology, geochemistry, or metabolic diversity of Chloroflexi, in addition to temperature, could determine the niche space of this highly versatile group. [ABSTRACT FROM AUTHOR]

The time evolution of microorganisms, such as bacteria, is of great interest in biology. In the article by D. Stanescu et al. [Electronic Transactions on Numerical Analysis, 34, 44–58 (2009)], a logistic model was proposed to model the growth of anaerobic photosynthetic bacteria. In the laboratory experiment, actual data for two species of bacteria were considered: Rhodobacter capsulatus and Chlorobium vibrioforme. In this paper, we suggest a new nonlinear model by assuming that the population growth rate is not proportional to the size of the bacteria population, but to the number of interactions between the microorganisms, and by taking into account the beginning of the death phase in the kinetic curve. Stanescu et al. evaluated the effect of randomness into the model coefficients by using generalized polynomial chaos (gPC) expansions, by setting arbitrary distributions without taking into account the likelihood of the data. By contrast, we utilize a Bayesian inverse approach for parameter estimation to obtain reliable posterior distributions for the random input coefficients in both the logistic and our new model. Since our new model does not possess an explicit solution, we use gPC expansions to construct the Bayesian model and to accelerate the Markov chain Monte Carlo algorithm for the Bayesian inference. [ABSTRACT FROM AUTHOR]

The present study evaluated the effects of five bacterial isolates from the microalga Muriellopsis sp. on the microalgal biomass concentration (g/L), specific growth rate (K), photosynthetic quantum yield (QY), non‐photochemical quenching (NPQ), maximum relative electron transport rates (rETR max) and levels of nutritional components such as carbohydrates, lipids, proteins and carotenoids in Muriellopsis sp. cultivated in seawater under indoor and outdoor conditions. The bacterial strains were Microbacterium sp. Dom 1; Pseudomonas sp. Dom2; Microbacterium sp. Dom 3; Rhizobium sp. Dom 4; and Dietzia sp. Dom 5, as well as the Pseudoalteromonas sp. (SLP1), a bacterium known to promote the growth of microalgae. At the laboratory level, inoculation of the strains SLP1, Dom 1, Dom 3 and Dom 5 resulted in higher specific growth rates and biomass of the microalga. Subsequently, the best results were obtained with a combination of the selected bacterial strains (Dom1, Dom 3, Dom5 and SLP1) under outdoor culture conditions improved the biomass, proteins, carbohydrates and total carotenoids in 22.12%, 48.28%, 19,25% and 48.27%, respectively, compared to cultures without the incorporation of the selected bacteria (control), while no effects were observed on the photosynthetic parameters. Thus, it was demonstrated that positive associations of the selected bacterial strains played an important role in the production of Muriellopsis sp. acclimatized to grow in seawater. This is of crucial importance, especially in desert areas, where solar radiation is high and freshwater is a limited resource. [ABSTRACT FROM AUTHOR]

The discovery of mid‐Proterozoic (1.8–0.8 billion years ago, Ga) indigenous biomarkers is a challenge, since biologically informative molecules of such antiquity are commonly destroyed by metamorphism or overprinted by drilling fluids and other anthropogenic petroleum products. Previously, the oldest clearly indigenous biomarkers were reported from the 1.64 Ga Barney Creek Formation in the northern Australian McArthur Basin. In this study, we present the discovery of biomarker molecules from carbonaceous shales of the 1.73 Ga Wollogorang Formation in the southern McArthur Basin, extending the biomarker record back in time by ~90 million years. The extracted hydrocarbons illustrate typical mid‐Proterozoic signatures with a large unresolved complex mixture, high methyl alkane/n‐alkane ratios and the absence of eukaryotic steranes. Acyclic isoprenoids, saturated carotenoid derivatives, bacterial hopanes and aromatic hopanoids and steroids also were below detection limits. However, continuous homologous series of low molecular weight C14–C19 2,3,4‐ and 2,3,6‐trimethyl aryl isoprenoids (AI) were identified, and C20–C22 AI homologues were tentatively identified. Based on elevated abundances relative to abiogenic isomers, we interpret the 2,3,6‐AI isomer series as biogenic molecules and the 2,3,4‐AI series as possibly biogenic. The biological sources for the 2,3,6‐AI series include carotenoids of cyanobacteria and/or green sulphur bacteria (Chlorobiaceae). The lower concentrated 2,3,4‐AI series may be derived from purple sulphur bacteria (Chromatiaceae). These degradation products of carotenoids are the oldest known clearly indigenous molecules of likely biogenic origin. [ABSTRACT FROM AUTHOR]

Cyanobacteria are photosynthetic bacteria that form a fundamental part of soil biocrusts, enhance soil function and structure, and can promote plant growth. We assessed the potential of cyanobacteria as a seed bio‐primer for mine‐site restoration in an arid region in Western Australia, examining its effects on native plant growth and the characteristics of mine soil substrates used in dryland restoration. Cyanobacteria strains indigenous to the study region (Leptolyngbya sp., Microcoleus sp., Nostoc sp., and Scytonema sp.) were used to create an inoculant. Seeds of seven native plant species were bio‐primed with the inoculant, and their germination and growth assessed in a laboratory experiment. Seedling growth after bio‐priming was assessed in a glasshouse experiment for a subset of three species, in two different substrates (topsoil and mine waste). Soil properties related to soil function, e.g. total organic carbon, total nitrogen, and microbial activity, were also measured. Minor effects on germination were recorded with only significantly higher germination rates reported in E. gamophylla. Soil parameters were generally higher in topsoil than in mine waste, regardless of bio‐priming treatment. However, bio‐priming resulted in seedlings of four species producing longer radicles and/or shoots. For example, seedling root lengths of bio‐primed G. wickhamii were 57% larger than the control treatment (30.1 ± 4.3 and 13.0 ± 1.6 mm, respectively); and shoots of T. wiseana were 54% longer in the bio‐primed treatment (18.6 ± 1.6 mm) compared to the control (8.53 ± 1.4 mm). Overall, our results highlight that bio‐priming with cyanobacteria may improve plant growth for some species commonly used in dryland restoration. [ABSTRACT FROM AUTHOR]