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Ribosomal RNA is the main constituent of ribosomes, where it not only provides a structural scaffold for r-proteins but also a decoding mechanism for the translation of mRNAs into proteins. Modulation of the cellular rRNA content is at the heart of the strictly regulated biosynthesis of ribosomes and allows the cells to adapt their translation machinery to environmental fluctuations. In bacteria, the genes encoding rRNA molecules are typically organised in operons. The operons encode large primary transcripts that are processed and chemically modified. The resulting rRNAs are assembled into ribosomes together with ribosomal proteins in a multistep process. The activity of the assembled ribosome is constantly monitored, and a large set of enzymes is responsible for rRNA quality control, repair and degradation in case of ribosomal damage. The synchronisation of these processes creates an elaborate network of reactions in charge of the synthesis of the translation apparatus, its modification in response to environmental changes and its protection against stress factors. This review illustrates the current knowledge of the key events that occur in the lifecycle of rRNA molecules in bacteria, and it highlights the importance of a fine regulation of rRNA content for the maintenance of ribosome homeostasis.

Phenotypic heterogeneity in clonal bacterial batch cultures is an important adaptive strategy to changing environments, including in diazotrophs with the unique capacity to convert di-nitrogen into bio-available ammonium. In diazotrophicKlebsiella oxytocawe simultaneously measured mRNA levels of key regulatory (glnK-amtB, nifLA) and structural (nifHDK) operons required for establishing nitrogen fixation, using dual molecule, single cell RNA-FISH. Through stochastic transcription models and mutual information analysis we revealed likely molecular origins for heterogeneity in nitrogenase expression. In wildtype and regulatory variant strains we inferred contributions from intrinsic and extrinsic noise, finding thatnifHDKtranscription is inherently bursty, but that noise propagation through signalling is also significant. The regulatory geneglnKhad the highest discernible effect onnifHDKvariance, while noise from factors outside of the regulatory pathway were negligible. Results provide evidence that heterogeneity is a fundamental property of this regulatory system, indicating potential constraints for engineering homogeneous nitrogenase expression.

CRISPR-associated Rossmann fold (CARF) domain signalling underpins the modulation of CRISPR-Cas systems. Unlike the majority of known CARF domains associated with nuclease activity in CRISPR-Cas systems, the CARF domain of the transcriptional regulator RtcR modulates the opposite function by activating an RNA end sealing system. The Rtc RNA repair system in Escherichia coli consists ofthe universally conserved RNA cyclase RtcA and RNA ligase RtcB, and is known to be induced by antibiotics and oxidative stress. We aim to investigate the CARF domain mediated transcriptional regulation of the Rtc system in vivo and in vitro. A reporter based assay confirmed that the RtcR CARF domain has a negative regulatory effect on RtcR activity and subsequent induction of the rtcBA operon. Both predictive modelling and site-directed mutagenesis suggest the Rtc induction is not due to oxidation of cysteines present in the RtcR regulatory CARF domain. Interestingly, the enzymes RtcA and RtcB, products of the actions of RtcR as a transcription regulator, are required for RtcR to stimulate expression of the rtcBA operon and directly bind to the RtcR CARF domain as shown in vivo by two-hybrid and in vitro by gel filtration. Given that CARF domains are known to be activated by RNA binding, a range of RNA molecules linked to the Rtc system or CARF domains in general are currently being investigated as potential inducers in an in vitro transcription system. Together, our data indicate an expanded range for CARF domain signalling, including via protein-protein interactions.

The article “Organic phosphorus in the terrestrial environment: a perspective on the state of the art and future priorities”, written by Timothy S George et al., was originally published with incorrect affiliation information for one of the co-authors, E. Klumpp.

The expression level of a gene can fluctuate significantly between individuals within a population of genetically identical cells. The resultant phenotypic heterogeneity could be exploited by bacteria to adapt to changing environmental conditions. Noise is hence a genome-wide phenomenon that arises from the stochastic nature of the biochemical reactions that take place during gene expression and the relatively low abundance of the molecules involved. The production of mRNA and proteins therefore occurs in bursts, with alternating episodes of high and low activity during transcription and translation. Single-cell and single-molecule studies demonstrated that noise within gene expression is influenced by a combination of both intrinsic and extrinsic factors. However, our mechanistic understanding of this process at the molecular level is still rather limited. Further investigation is necessary that takes into account the detailed knowledge of gene regulation gained from biochemical studies.

aenibacillus polymyxa has been shown to have great potential as a bio-fertiliser and biocontrol agent, however information regarding its effect on below-ground biota when used as a soil additive is scarce. Below-ground biota provide vital services to boost plant performance and thus knowledge regarding their response to bio-fertiliser and biocontrol agents is critical for future crop management.Here, we extracted below-ground nematode (N) and microbial communities (M) and reassembled them in presence and absence of P. polymyxa soil inoculation (P). We then assessed the impacts of each of the three components, individually and in combination, on nematode community structure and plant growth.The main pattern was a gradual shift in the below-ground nematode community from those with increased abundances of omnivorous and plant parasitic nematodes towards those with increased abundances of predatory nematodes along the treatment gradient from N, to N,M to N,P to N,M,P. This shift from increased abundances of omnivores and plant parasitic nematodes to increased abundances of predatory nematodes was significantly positively correlated with plant growth.In conclusion, our study demonstrates for the first time that inoculation of soil with P. polymyxa changes the below-ground nematode community resulting in significant changes to plant growth.

Enhancer-dependent transcription involving the promoter specificity factor σ(54) is widely distributed amongst bacteria and commonly associated with cell envelope function. For transcription initiation, σ(54)-RNA polymerase yields open promoter complexes through its remodelling by cognate AAA+ ATPase activators. Since activators can be bypassed in vitro, bypass transcription in vivo could be a source of emergent gene expression along evolutionary pathways yielding new control networks and transcription patterns. At a single test promoter in vivo bypass transcription was not observed. We now use genome-wide transcription profiling, genome-wide mutagenesis and gene over-expression strategies in Escherichia coli, to (i) scope the range of bypass transcription in vivo and (ii) identify genes which might alter bypass transcription in vivo. We find little evidence for pervasive bypass transcription in vivo with only a small subset of σ(54) promoters functioning without activators. Results also suggest no one gene limits bypass transcription in vivo, arguing bypass transcription is strongly kept in check. Promoter sequences subject to repression by σ(54) were evident, indicating loss of rpoN (encoding σ(54)) rather than creating rpoN bypass alleles would be one evolutionary route for new gene expression patterns. Finally, cold-shock promoters showed unusual σ(54)-dependence in vivo not readily correlated with conventional σ(54) binding-sites.

Made available in DSpace on 2018-12-11T16:49:52Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-06-01 Biotechnology and Biological Sciences Research Council Background: The dynamics of phosphorus (P) in the environment is important for regulating nutrient cycles in natural and managed ecosystems and an integral part in assessing biological resilience against environmental change. Organic P (Po) compounds play key roles in biological and ecosystems function in the terrestrial environment being critical to cell function, growth and reproduction. Scope: We asked a group of experts to consider the global issues associated with Po in the terrestrial environment, methodological strengths and weaknesses, benefits to be gained from understanding the Po cycle, and to set priorities for Po research. Conclusions: We identified seven key opportunities for Po research including: the need for integrated, quality controlled and functionally based methodologies; assessment of stoichiometry with other elements in organic matter; understanding the dynamics of Po in natural and managed systems; the role of microorganisms in controlling Po cycles; the implications of nanoparticles in the environment and the need for better modelling and communication of the research. Each priority is discussed and a statement of intent for the Po research community is made that highlights there are key contributions to be made toward understanding biogeochemical cycles, dynamics and function of natural ecosystems and the management of agricultural systems. The James Hutton Institute Lancaster Environment Centre Lancaster University Lincoln University, Lincoln Universidade Estadual do Norte Fluminense Darcy Ribeiro (UENF - Laboratório de Solos), Av. Alberto Lamego 2000 Plant and Soil Sciences University of Delaware, 160 Townsend Hall Faculty of Environment and Natural Resources Chair of Soil Ecology University of Freiburg, Bertoldstraße 17 Rothamsted Research West Common Harpenden Rothamsted Research West Common Harpenden, North Wyke College of Agricultural Sciences Department of Crop Science Sao Paulo State University (UNESP), 1780, Jose Barbosa de Barros st Institute of Bio- and Geosciences IBG-3: Agrosphere Forschungszentrum Jülich GmbH Oak Ridge National Laboratory, P.O.Box 2008 DISAFA Soil Biogeochemistry University of Turin, largo Braccini 2 University of Minnesota-, Cities, 1479 Gortner Ave. Saint Paul China Agricultural University Le Laboratoire des Sciences du Climat et de l’Environnement IPSL-LSCE CEA/CNRS/UVSQ Saclay Institute of Soil Science University of Hohenheim, Emil Wolff Str. 27 INRA UMR ECO&SOLS Evolutionary Biology Centre EBC, Kåbovägen 4, house 7 Centre for Agri-environmental Research School of Agriculture Policy and Development University of Reading, Whiteknights, PO Box 237 Climate Impacts Research Centre Dep. of Ecology and Environmental Science Umeå University CSIRO Agriculture & Food D-USYS ETH Zurich, Tannenstrasse 1 Department of Environmental Sciences Norwegian University of Life Sciences, Post Box 5003 University of Guelph, 50 Stone Road East National Institute of Agricultural Research of Uruguay Department of Chemical & Biological Engineering The University of Sheffield, Mappin Street, S1 3JD School of Biological Sciences University of East Anglia, Norwich Research Park, Norwich International Plant Nutrition Institute, 18 Maplewood Drive Centro Interdipartimentale di Ricerca sulla Risonanza Magnetica Nucleare per l’Ambiente l’Agro-Alimentare ed i Nuovi Materiali (CERMANU) Università di Napoli Federico II, Via Università 100 Universidad de La Frontera School of Environment and Life Sciences University of Salford School of the Environment Natural Resources and Geography Bangor University School of Biological Sciences and Institute for Global Food Security The Queen’s University of Belfast, Medical Biology Centre, 97 Lisburn Road CENA University of Sao Paulo, Avenida Centenario, 303 Teagasc Environmental Research Centre, Johnstown Castle Centre for Ecology & Hydrology, Library Avenue, Bailrigg Department of Soil Biogeochemistry Bayreuth Center of Ecology and Environmental Research (BayCEER) University Bayreuth, Dr.-Hans-Frisch-Str. 1-3 Guangdong Provincial Key Laboratory of Applied Botany South China Botanical Garden Chinese Academy of Sciences, 723 Xingke Road, Tianhe District School of Geographical Sciences & School of Chemistry University of Bristol, University Road Soil Science and Soil Protection Martin Luther University Halle-Wittenberg, von-Seckendorff-Platz 3 Centre for Ice and Climate Niels Bohr Institute University of Copenhagen NERC Isotope Geosciences Facility British Geological Survey Department of Microbiology and Ecosystem Science University of Vienna, Althanstrasse 14 University of Northern British Columbia, 3333 University Way Brigham Young University Centre for Environmental Sciences Hasselt University Building D, Agoralaan Yamagata University Department of Biology Lund University, Biology Building Sölvegatan 35 Assessment of Microbial Environment Graduate School of Biosphere Science Hiroshima University College of Agricultural Sciences Department of Crop Science Sao Paulo State University (UNESP), 1780, Jose Barbosa de Barros st Biotechnology and Biological Sciences Research Council: BB/K018167/1 Biotechnology and Biological Sciences Research Council: BB/L025671/2

Phage shock proteins (Psp) and their homologues are found in species from the three domains of life: Bacteria, Archaea and Eukarya (e.g. higher plants). In enterobacteria, the Psp response helps to maintain the proton motive force (PMF) of the cell when the inner membrane integrity is impaired. The presumed ability of ArcB to sense redox changes in the cellular quinone pool and the strong decrease of psp induction in ΔubiG or ΔarcAB backgrounds suggest a link between the Psp response and the quinone pool. The authors now provide evidence indicating that the physiological signal for inducing psp by secretin-induced stress is neither the quinone redox state nor a drop in PMF. Neither the loss of the H+-gradient nor the dissipation of the electrical potential alone is sufficient to induce the Psp response. A set of electron transport mutants differing in their redox states due to the lack of a NADH dehydrogenase and a quinol oxidase, but retaining a normal PMF displayed low levels of psp induction inversely related to oxidised ubiquinone levels under microaerobic growth and independent of PMF. In contrast, cells displaying higher secretin induced psp expression showed increased levels of ubiquinone. Taken together, this study suggests that not a single but likely multiple signals are needed to be integrated to induce the Psp response. Electronic supplementary material The online version of this article (doi:10.1007/s00284-011-9869-5) contains supplementary material, which is available to authorized users.

Sensing the environment and responding appropriately to it are key capabilities for the survival of an organism. All extant organisms must have evolved suitable sensors, signaling systems, and response mechanisms allowing them to survive under the conditions they are likely to encounter. Here, we investigate in detail the evolutionary history of one such system: The phage shock protein (Psp) stress response system is an important part of the stress response machinery in many bacteria, including Escherichia coli K12. Here, we use a systematic analysis of the genes that make up and regulate the Psp system in E. coli in order to elucidate the evolutionary history of the system. We compare gene sharing, sequence evolution, and conservation of protein-coding as well as noncoding DNA sequences and link these to comparative analyses of genome/operon organization across 698 bacterial genomes. Finally, we evaluate experimentally the biological advantage/disadvantage of a simplified version of the Psp system under different oxygen-related environments. Our results suggest that the Psp system evolved around a core response mechanism by gradually co-opting genes into the system to provide more nuanced sensory, signaling, and effector functionalities. We find that recruitment of new genes into the response machinery is closely linked to incorporation of these genes into a psp operon as is seen in E. coli, which contains the bulk of genes involved in the response. The organization of this operon allows for surprising levels of additional transcriptional control and flexibility. The results discussed here suggest that the components of such signaling systems will only be evolutionarily conserved if the overall functionality of the system can be maintained.

The bacterial phage shock protein (Psp) response functions to help cells manage the impacts of agents impairing cell membrane function. The system has relevance to biotechnology and to medicine. Originally discovered in Escherichia coli, Psp proteins and homologues are found in Gram-positive and Gram-negative bacteria, in archaea and in plants. Study of the E. coli and Yersinia enterocolitica Psp systems provides insights into how membrane-associated sensory Psp proteins might perceive membrane stress, signal to the transcription apparatus and use an ATP-hydrolysing transcription activator to produce effector proteins to overcome the stress. Progress in understanding the mechanism of signal transduction by the membrane-bound Psp proteins, regulation of the psp gene-specific transcription activator and the cell biology of the system is presented and discussed. Many features of the action of the Psp system appear to be dominated by states of self-association of the master effector, PspA, and the transcription activator, PspF, alongside a signalling pathway that displays strong conditionality in its requirement.

The phage-shock-protein (Psp) response maintains the proton-motive force (pmf) under extracytoplasmic stress conditions that impair the inner membrane (IM) in bacterial cells. InEscherichia colitranscription of thepspABCDEandpspGgenes requires activation ofσ54-RNA polymerase by the enhancer-binding protein PspF. A regulatory network comprising PspF–A–C–B–ArcB controlspspexpression. One key regulatory point is the negative control of PspF imposed by its binding to PspA. It has been proposed that under stress conditions, the IM-bound sensors PspB and PspC receive and transduce the signal(s) to PspA via protein–protein interactions, resulting in the release of the PspA–PspF inhibitory complex and the consequent induction ofpsp. In this work we demonstrate that PspB self-associates and interacts with PspC via putative IM regions. We present evidence suggesting that PspC has two topologies and that conserved residue G48 and the putative leucine zipper motif are determinants required for PspA interaction and signal transduction upon stress. We also establish that PspC directly interacts with the effector PspG, and show that PspG self-associates. These results are discussed in the context of formation and function of the Psp regulatory complex.

To survive and colonise their various environments, including those used during infection, bacteria have developed a variety of adaptive systems. Amongst these is phage shock protein (Psp) response, which can be induced in Escherichia coli upon filamentous phage infection (specifically phage secretin pIV) and by other membrane-damaging agents. The E. coli Psp system comprises seven proteins, of which PspA is the central component. PspA is a bifunctional protein that is directly involved in (i) the negative regulation of the psp-specific transcriptional activator PspF and (ii) the maintenance of membrane integrity in a mechanism proposed to involve the formation of a 36-mer ring complex. Here we established that the PspA negative regulation of PspF ATPase activity is the result of a cooperative inhibition. We present biochemical evidence showing that an inhibitory PspA–PspF regulatory complex, which has significantly reduced PspF ATPase activity, is composed of around six PspF subunits and six PspA subunits, suggesting that PspA exists in at least two different oligomeric assemblies. We now establish that all four putative helical domains of PspA are critical for the formation of the 36-mer. In contrast, not all four helical domains are required for the formation of the inhibitory PspA–PspF complex. Since a range of initial PspF oligomeric states permit formation of the apparent PspA–PspF dodecameric assembly, we conclude that PspA and PspF demonstrate a strong propensity to self-assemble into a single defined heteromeric regulatory complex.

The phage shock protein (Psp) system found in enterobacteria is induced in response to impaired inner membrane integrity (where the Psp response is thought to help maintain the proton motive force of the cell) and is implicated in the virulence of pathogens such as Yersinia and Salmonella. We provided evidence that the two-component ArcAB system was involved in induction of the Psp response in Escherichia coli and now report that role of ArcAB is conditional. ArcAB, predominantly through the action of ArcA regulated genes, but also via a direct ArcB-Psp interaction, is required to propagate the protein IV (pIV)-dependent psp-inducing signal(s) during microaerobiosis, but not during aerobiosis or anaerobiosis. We show that ArcB directly interacts with the PspB, possibly by means of the PspB leucine zipper motif, thereby allowing cross-communication between the two systems. In addition we demonstrate that the pIV-dependent induction of psp expression in anaerobiosis is independent of PspBC, establishing that PspA and PspF can function as a minimal Psp system responsive to inner membrane stress.

Here we describe approaches and methods to assaying in vitro the major variant bacterial sigma factor, Sigma 54 (σ(54)), in a purified system. We include the complete transcription system, binding interactions between σ54 and its activators, as well as the self-assembly and the critical ATPase activity of the cognate activators which serve to remodel the closed promoter complexes. We also present in vivo methodologies that are used to study the impact of physiological processes, metabolic states, global signalling networks, and cellular architecture on the control of σ(54)-dependent gene expression.

The bacterial plant pathogen Pseudomonas syringae causes disease in a wide range of plants. The associated decrease in crop yields results in economic losses and threatens global food security. Competition exists between the plant immune system and the pathogen, the basic principles of which can be applied to animal infection pathways. P. syringae uses a type III secretion system (T3SS) to deliver virulence factors into the plant that promote survival of the bacterium. The P. syringae T3SS is a product of the hypersensitive response and pathogenicity (hrp) and hypersensitive response and conserved (hrc) gene cluster, which is strictly controlled by the codependent enhancer-binding proteins HrpR and HrpS. Through a combination of bacterial gene regulation and phenotypic studies, plant infection assays, and plant hormone quantifications, we now report that Chp8 (i) is embedded in the Hrp regulon and expressed in response to plant signals and HrpRS, (ii) is a functional diguanylate cyclase, (iii) decreases the expression of the major pathogen-associated molecular pattern (PAMP) flagellin and increases extracellular polysaccharides (EPS), and (iv) impacts the salicylic acid/jasmonic acid hormonal immune response and disease progression. We propose that Chp8 expression dampens PAMP-triggered immunity during early plant infection., IMPORTANCE The global demand for food is projected to rise by 50% by 2030 and, as such, represents one of the major challenges of the 21st century, requiring improved crop management. Diseases caused by plant pathogens decrease crop yields, result in significant economic losses, and threaten global food security. Gaining mechanistic insights into the events at the plant-pathogen interface and employing this knowledge to make crops more resilient is one important strategy for improving crop management. Plant-pathogen interactions are characterized by the sophisticated interplay between plant immunity elicited upon pathogen recognition and immune evasion by the pathogen. Here, we identify Chp8 as a contributor to the major effort of the plant pathogen Pseudomonas syringae pv. tomato DC3000 to evade immune responses of the plant.

It is indisputable: The decision to purchase a certain product is affected much more by emotions than it is by reason. This has become a truism amongst all companies producing brand quality consumer goods. Brands try to add an underlying philosophy or attitude to products, so that in this world where basic needs are satisfied, consumers buy to a great part the values connected with a product instead of buying the product itself. Ever since it became clear that the purchase of a new car does not serve the need of locomotion but the achievement of a social standard, AUDI has not sold cars but rather “Vorsprung durch Technik” (advancement through technology); BMW sells the lifestyle of “sportive driving” and Geox “breathes”. Brands serve the purpose of making customers feel loyal to their “values”. The brand gives the customer confidence, and the customer trusts the brand.

We report a general method based on wide-field fluorescence imaging of single molecule photobleaching and the Chung–Kennedy algorithm to measure the stoichiometry of functional protein complexes in living bacterial cells.

The evolution of proteins is inseparably linked to their function. Because most biological processes involve a number of different proteins, it may become impossible to study the evolutionary properties of proteins in isolation. In the present article, we show how simple mechanistic models of biological processes can complement conventional comparative analyses of biological traits. We use the specific example of the phage-shock stress response, which has been well characterized in Escherichia coli, to elucidate patterns of gene sharing and sequence conservation across bacterial species.

The phage shock protein (Psp) response in Gram-negative bacteria counteracts membrane stress. Transcription of the PspF regulon (pspABCDE and pspG) in Escherichia coli is induced upon stresses that dissipate the proton motive force (pmf). Using GFP fusions we have visualized the subcellular localizations of PspA (a negative regulator and effector of Psp) and PspG (an effector of Psp). It has previously been proposed that PspA evenly coates the inner membrane of the cell. We now demonstrate that instead of uniformly covering the entire cell, PspA (and PspG) is highly organized into what appear to be distinct functional classes (complexes at the cell pole and the lateral cell wall). Real-time observations revealed lateral PspA and PspG complexes are highly mobile, but absent in cells lacking MreB. Without the MreB cytoskeleton, induction of the Psp response is still observed, yet these cells fail to maintain pmf under stress conditions. The two spatial subspecies therefore appear to be dynamically and functionally distinct with the polar clusters being associated with sensory function and the mobile complexes with maintenance of pmf.

Staphylococcus (S.) aureus can cause serious infections toxinoses and life threatening illnesses. Staphylocoagulase production represents the major criterion for detection of S. aureus isolates. As coagulase deficient clinical isolates of S. aureus have been described additional use of chromogenic media in S. aureus detection was postulated to represent a highly specific (97) and sensitive (99 after 48h) tool in the identification of the organism. In this study we further investigated genotypic and phenotypic characteristics of a coagulase and a glucosidase deficient variant of S. aureus obtained from bovine mastitis milk. MSSA_129 was identified as S. aureus by species specific PCR MALDI TOF (ID 99.90) and DNA microarray and could be assigned to spa type t543 clonal complex CC479 agr type II and capsule type 8. Still no opaque zone was visible on rabbit plasma fibrinogen agar (RPF Oxoid Cambridge United Kingdom). On S. aureus ID agar (SAID Biomérieux La Balme les Grottes France) bright yellow colonies instead of the characteristic green colonies were formed. Determination of the nucleotide sequence of coa revealed a deletion at nucleotide position 653 within the D2 region of the gene leading to a frameshift. Although coa is known to represent a highly polymorphic region it can be divided into six common regions: the signal sequence the D1 and D2 regions enabling contact with prothrombin the central region a repeat region and the C terminal sequence. The detected frameshift results in the reading of a premature stop codon at amino acid position 224 thus rendering the polypeptide abnormally short and most likely not functional. The a glucosidase gene of MSSA_129 and its upstream region were compared to sequences available at Genbank. Although no strain possesses an a glucosidase gene exactly identical over its full length to the one found in MSSA_129 no unique amino acid changes were found. However variabilty of amino acid sequences on 12 positions (position 43 83 88 133 439 448 454 462 492 514 519 and 539) within the available sequences was noticed. Considering amino acids found at these positions strain MSSA_129 showed a unique combination. Directly upstream of the a glucosidase gene (malA) we identified a sequence homologous to malR a putative transcriptional regulator involved in maltose transport in Staphylococcus xylosus. In S. xylosus the malRA genes are cotranscribed and constitute an essential locus for maltosaccharide utilization. MSSA_129 malR exhibited several unique amino acid changes. Expression levels of malA were compared among MSSA_129 and two phenotypically a glucosidase positive strains LRA1 and HG003 by quantitative Real Time PCR. As MSSA_129 expressed malA in similar levels compared to HG003 and even in significantly higher levels than in LRA1 (p = 0.01) the hypothesis that the yellow phenotype may be due to a negative effect of malR polymorphisms on malA expression was dismissed. Complementation of MSSA_129 with the a glucosidase gene of strain HG003 on a plasmid rescued the green phenotype on SAID agar. Complementation of MSSA_129 with its own malA or an empty vector did not alter the phenotype on SAID. We therefore suggest the atypical phenotype on SAID to be due to the sequence polymorphisms discovered in the MSSA_129 a glucosidase gene. Considering our findings screening for S. aureus by only RPF and SAID agar harbors the risk of false negative results potentially leading to severe therapeutic mistakes.