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[Display omitted] • Citricoccus sp. P2 degraded 44.63% of lignin and produced 23.96% of lipid content. • Citricoccus sp. P2 has demonstrated high effectiveness in LDCs conversion. • Genome sequencing revealed a biological funneling pathway for LDCs into lipid. • Lipid yield was 0.39 g/g LMS-treated lignin. • Non-sterilized fermentation efficiently improved lipid production from LDCs. Lignin-derived compounds (LDCs) bioconversion into lipids is a promising yet challenging task. This study focuses on the isolation of the ligninolytic bacterium Citricoccus sp. P2 and investigates its mechanism for producing lipids from LDCs. Although strain P2 exhibits a relatively low lignin degradation rate of 44.63%, it efficiently degrades various concentrations of LDCs. The highest degradation rate is observed when incubated with 0.6 g/L vanillic acid, 0.6 g/L syringic acid, 0.8 g/L p-coumaric acid, and 0.4 g/L phenol, resulting in respective lipid yields of 0.16 g/L, 0.13 g/L, 0.24 g/L, and 0.13 g/L. The genome of strain P2 provides insights into LDCs bioconversion into lipids and stress tolerance. Moreover, Citricoccus sp. P2 has been successfully developed a non-sterilized lipid production using its native alkali-halophilic characteristics, which significantly enhances the lipid yield. This study presents a promising platform for lipids production from LDCs and has potential to promote valorization of lignin. [ABSTRACT FROM AUTHOR]

Lignin bioconversion into polyhydroxybutyrate (PHB) has emerged as a promising valorization, however, it is suffering from inadequate conversion efficiency. Herein, an efficient strategy for addressing this challenge by employing an alkali-halophilic strain Halomonas alkalicola M2 is developed. Up to 58.5% of lignin is degraded when incubates in the non-sterilized lignin (NSL) medium under a glucose concentration of 1.055 g/L, peptone concentration of 0.596 g/L, and incubation time of 6.89 d, demonstrating enhanced proficiency compared to thermally sterilized lignin (TSL) method due to the improved cell growth, lignin-degrading enzyme activities, and secreted protein contents. Consequently, PHB production demonstrates a 50% increase using NSL method compared to TSL method. A separate route of enzymatic hydrolysis and fermentation (SHF) is proposed to further improve the PHB production, resulting in a record yield of PHB which is 1.89 g/L. This work creatively develops a non-sterilization strategy to improve PHB production from lignin, showing great potential for promoting biological lignin valorization. [Display omitted] • Non-sterilization efficiently increased the lignin degradation rate to 58.5%. • NSL produced higher cell growth, enzyme activity, and secreted protein contents. • Approximately 1.5-fold PHB titer was produced in the NSL medium. • Developed a non-sterilized SHF with a record yield of 1.89 g/L PHB production. [ABSTRACT FROM AUTHOR]

[Display omitted] • An alkali-halophilic was isolated for lignin degradation and PHA production. • An open unsterile PHA production from lignocellulose was developed. • A record yield of 2.1 g/L PHA was produced from the APL. • A total of 5.9 g PHA was accumulated from 100 g bamboo powder. The alkali-halophilic Halomonas alkalicola M2 was isolated and developed for an open unsterile polyhydroxyalkanoate (PHA) fermentation from lignocellulose at pH 10.0 and NaCl 70 g/L. The alkaline pretreatment liquid (APL) was converted into PHA by the strain, which was significantly affected by the cultural conditions, including pH, NaCl concentration, nitrogen source, and APL concentration. The extracted PHA was composed of three monomers and similar in physicochemical properties to conventional short chain-length PHA. A record yield of 2.1 and 5.9 g of PHA was accumulated from 100 g dry bamboo powder (BP) by using APL and APL combined with hydrolysate during a 48-h open unsterile fermentation process, respectively. In summary, the alkali-halophilic H. alkalicola M2 achieved the open unsterile fermentation for lignocellulose efficient bioconversion into PHA under high alkalinity and salinity conditions and would be an ideal producer in the field. [ABSTRACT FROM AUTHOR]

[Display omitted] • Halomonas sp. Y3 secreted laccase through Tat and Type I secretion system. • Biodesign of a highly efficient laccase secretion apparatus. • Heterologous expression of laccase achieved enzyme activity of 184 U/mL. • Up to 55 % lignin was degraded by the engineered strain Y3_05. • Co-transformation of Y3_05 and Y3_08 produced 740 and 1314 mg/L from lignin and APL. Lignin degradation represents a significant challenge in biological valorization, but it is suffering from insufficiency, putting barriers to efficient lignin conversion. Herein, the study first develops a highly efficient laccase secretion apparatus, enabling high enzyme activity of 184 U/mL, complementing the biochemical limits on lignin depolymerization well in Halomonas sp. Y3. Further engineering of PHA biosynthesis produces a significantly high PHA titer of 286, 742, and 868 mg/L from alkaline lignin, catechol, and protocatechuate, respectively. The integration of laccase-secretion and PHA production modules enables a record titer of 693 and 1209 mg/L in converting lignin and lignin-containing stream to PHA, respectively. The titer is improved furtherly to 740 and 1314 mg/L by developing a non-sterilized fermentation. This study advances a cheaper and greener production of valuable chemicals from lignin by constructing a biosynthetic platform for PHA production and provides novel insight into the lignin conversion by extremophilic microbes. [ABSTRACT FROM AUTHOR]

Insects and gut symbiotic bacteria have shown promise in the degradation of lignocellulosic biomass (LCB). Cyrtotrachelus buqueti is being studied as a resource for LCB degradation, but its mechanisms are not fully understood. This study investigates the host transcriptome and gut microbiome to identify the inherent mechanisms behind efficient LCB degradation. The gut secretory protein showed degradation rates of 30.23%− 38.24% for cellulose, 58.56%− 70.96% for hemicellulose, and 28.71%− 43.43% for lignin, while microbiota had degradation rates of 28.41%− 38.31% for cellulose, 53.45%− 66.15% for hemicellulose, and 25.65%− 38.37% for lignin. Core genera (>80%) of bacteria are identified in the foregut, midgut, and hindgut, with the hindgut containing the most abundant lignin degradation potential genera Serratia and Dysgonomonas , and the midgut has the highest abundance of cellulose and hemicellulose degradation likely genera Lactococcus and Enterococcus. The transcriptome reveals highly abundant and diversified lignocellulolytic genes encoding carbohydrate-active enzymes (CAZymes), with lignin-modifying enzyme genes highly expressed in the hindgut and cellulase and hemicellulase genes highly expressed in the foregut and midgut. Integrative analysis reveals a significant correlation between the gut microbiome and transcriptome, contributing to efficient LCB degradation. This study first provides a deeply comprehensive insight into the unique mechanisms of LCB degradation by C. buqueti. [Display omitted] • Lignocellulose was effectively degraded by the gut secretory protein and microbiota. • Microbiome and transcriptome analysis identified the core microbiota and CAZymes. • Microbiome and transcriptome intensely correlated revealed by integrative analysis. • Revealed the mechanism for lignocellulose degradation by bamboo snout beetle. [ABSTRACT FROM AUTHOR]

Poly(3-hydroxybutyrate- co -3-hydroxyvalerate) (PHBV) is a biopolyester with great potential, but its high production cost via the propionate-dependent pathway has hindered its development. Herein, we engineer Halomonas sp. Y3 to achieve efficient conversion of various LDCs into PHBV without propionate supplement. Initially, we successfully achieve PHBV production without propionate supplement by overexpressing threonine synthesis. The resulting biopolyester exhibits a 3 HV proportion of up to 7.89 mol%, comparable to commercial PHBV (8 mol%) available from Sigma Aldrich (403105). To further enhance PHBV production, we rationally design the reconstruction of aromatic compound catabolism. The engineered strain Y3_18 efficiently assimilates all LDCs containing syringyl (S), guaiacyl (G), and p -hydroxyphenyl-type (H) units. From 1 g/L of S-, G-, and H-type LDCs, Y3_18 produces PHBV at levels of 449 mg/L, 488 mg/L, and 716 mg/L, respectively, with yields of 44.9 % (g/g), 48.8 % (g/g), and 71.6 % (g/g). Moreover, to improve PHBV yield from lignin, we integrate laccase-secretion and PHBV production modules. This integration leads to the accumulation of 425.84 mg/L of PHBV with a yield of 21.29 % (g/g) and a 3 HV proportion of 6.38 mol%. By harnessing the capabilities of Halomonas sp. Y3, we demonstrate an efficient and sustainable approach for PHBV production from a variety of LDCs. • PHBV production from LDCs by Halomonas sp. Y3 via the propionate-dependent pathway • Knockout PrpC enabled PHBV production from LDCs without propionate supplementation. • Overexpressing threonine synthesis pathway improved PHBV production from LDCs. • Engineering aromatic compound catabolism improving PHBV content and 3 HV proportion • Co-transformation of Y3_05 and Y3_18 produced 426 mg/L of PHBV from lignin. [ABSTRACT FROM AUTHOR]

Polyhydroxybutyrate (PHB) production from lignocellulosic biomass is challenging due to the need for whole components and energy-effective conversion. Herein, Halomonas sp. Y3, a ligninolytic bacterium with the capacity to produce PHB from lignin and cellulose- and hemicellulose-derived sugars, is employed to explore its feasibility. This strain shows high sugar tolerance up to 200 g/L of glucose and 120 g/L of xylose. A dual anti-microbial contamination system (DACS) containing alkali-halophilic system (AHS) and phosphite-urea system (PUS) is presented, successfully achieving a completely aseptic effect and resulting in a total of 8.2 g of PHB production from 100 g bamboo biomass. We further develop a stage-fed-batch fermentation to promote the complete utilization of xylose. Approximately 69.99 g of dry cell weight (DCW) and 46.45 g of PHB with 66.35 % are obtained from a total of 296.58 g of sugars and 5.70 g of lignin, showing a significant advancement for LCB bioconversion. We then delete the native phosphate transporters, rendering the strain unable to grow on phosphate-loaded media, effectively improving the strain biosafety without compromising its ability to produce PHB. Overall, our findings demonstrate the potential of Y3 as a classic bacterium strain for PHB production with potential uses in industry. [Display omitted] • Halomonas sp. Y3 demonstrated high efficiency in converting whole LCB into PHB. • Non-sterilized PHB production by Y3 via a dual antimicrobial contamination system • PHB of 46.45 g was synthesized via non-sterilized stage-fed-batch fermentation of LCB. • Deletion of the native Pi transporters improved the biosafety of strain Y3. [ABSTRACT FROM AUTHOR]