Lactic acid bacteria (LAB) exopolysaccharides (EPSs) have garnered significant scientific interest due to their multifaceted roles in food technology and health promotion. This comprehensive review systematically examines the structural classification of LAB EPSs, emphasizing distinctions between homo-and heteropolysaccharides, as well as the influence of substituent groups (e. g., acetyl, phosphate) on their physicochemical and bioactive properties. Advanced isolation methodologies, including ethanol precipitation and ultrafiltration, coupled with characterization techniques such as nuclear magnetic resonance (NMR) spectroscopy and atomic force microscopy (AFM), are vital for deciphering their chemical and physical characteristics. The biosynthesis pathway, governed by eps operons and modulated by environmental factors (e.g., carbon sources, Ca²⁺), are discussed as targets for genetic engineering to enhance yield and functionality. Functionally, LAB EPSs display antioxidant, immunomodulatory, anti-tumor, anti-viral, and anti-biofilm activities, with demonstrated applications as natural additives in the food industry, prebiotics, and drug delivery systems. Despite their potential, challenges such as cost-effective production and regulatory hurdles persist. Future research should prioritize the elucidation of molecular mechanisms, clinical validation of health claims, and sustainable bioprocessing innovations to fully harness the transformative potential of LAB EPSs across food, pharmaceutical, and agricultural industries.

During our conveying the microbial structures of phycosphere microbiota (PM) derived from diverse marine harmful algal bloom (HAB) dinoflagellates, a new rod-sharped, white-colored cultivable bacterial strain, designated as LZ-15-2, was isolated from the PM of highly toxic Alexandrium catenella LZT09. Phylogenetic analysis of 16S rRNA gene sequence indicated that strain LZ-15-2 belonged to the genus Marivita within the family Rhodobacteraceae, and demonstrated the highest gene similarity of 99.2% to M. cryptomonadis CL-SK44^T, and less than 98.65% with other type strains of Marivita. Phylogenomic calculations on average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values between the new isolate and M. cryptomonadis CL-SK44^T were 99.86% and 99.88%, respectively. Genomic comparison of strain LZ-15-2 with available genomes of Marivita species further verified its taxonomic position within the genus of Marivita. Moreover, comparative genomics analysis showed a proximal similarity of strain LZ-15-2 with M. cryptomonadis CL-SK44^T, and it also revealed an open pan-genome status based on constructed gene accumulation curves among Marivita members with 9,361 and 1,712 genes for the pan- and core-genome analysis, respectively. Based on combined polyphasic taxonomic characteristics, strain LZ-15-2 represents a new member of M. cryptomonadis, and proposed as a potential candidate for further exploration of the detailed mechanisms governing the dynamic cross-kingdom algae–bacteria interactions (ABI) between PM and their algal host LZT09.

Reuterin, a mixture of different forms of 3-hydroxypropanal (3-HPA), including HPA hydrate and HPA dimer, is an antimicrobial compound converted from glycerol by Lactobacillus reuteri and other strains. Although its antimicrobial function may be related to its interaction with thiol groups, its temperature stability and effect on the gut environment remain unclear. The present study evaluated the antimicrobial effects and activity of reuterin against Escherichia coli and Salmonella typhimurium. Utilization of a reliable in vitro gut microbiome fermentation system revealed that reuterin has a modulatory effect on the gut microbial community. Reuterin treatment completely inhibited H₂ and NH₃ production in the gut and significantly enhanced the synthesis of branched short-chain fatty acids. 16s rRNA sequencing indicated that reuterin promoted the growth of Proteobacteria and Bacteroidetes in the in vitro system and significantly modulated gut microbiota composition.

A taxonomic study was carried out on a novel algae-associated bacterial strain Z3-1^T, which was isolated from phycosphere microbiota of toxic marine dinoflagellate Alexandrium tamarense 880. Cells of strain Z3-1^T were Gram-stain-negative, rod-shaped and strictly aerobic and were motile by means of flagella. Strain Z3-1^T grew at 25–42 °C, pH 5.0–10.0 and 1.0–5.0 % (w/v) NaCl. Strain Z3-1^T reduced nitrate to nitrite, but did not reduce nitrite to nitrogen gas. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain Z3-1^T belongs to the genus Nitratireductor showing the highest sequence similarity (97.0 %) to Nitratireductor basaltis JCM 14935^T. The average nucleotide identity and digital DNA–DNA hybridization relatedness between strain Z3-1^T and type strains of genus Nitratireductor with available genome sequences were in the ranges of 72.4–74.4 % and 22.7–23.3 %, respectively. The major fatty acids were summed in feature 8 (C_18:1 ω7c and/or C_18:1 ω6c), C_19:0 ω8c cyclo, C_18:1 ω7c 11-metyl and iso-C_17:0. The major polar lipids were determined as diphosphatidylglycerol, phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol, two unidentified phospholipids and four unidentified polar lipids. The genomic DNA G+C content calculated from genome sequence was 65.6 mol%. Based on genotypic, chemotaxonomic and phenotypic data obtained, strain Z3-1^T represents a novel species of the genus Nitratireductor , for which the name Nitratireductor alexandrii sp. nov. is proposed with the type strain Z3-1^T (=KCTC 62458^T=CCTCC AB 2017227^T).

Bacterioplankton communities are critical components of varied ecosystems in the oceans. Their occurrences represent a variety of connections between environmental and ecological elements. However, our current knowledge about the shaping factors of surface bacterioplankton communities in the eastern East China Sea (ECS) is still limited. In this study, we reveal the spatial patterns of the taxonomic and functional profiles of the surface bacterioplankton communitiesies in the nearshore and offshore areas in the eastern ECS, based on 16S rRNA gene pyrosequencing and functional annotation analysis. The obtained results show that the surface bacterioplankton communities in the nearshore areas are mainly dominated by the firmicutes (85.9%), actinobacteria (8.1%), and proteobacteria (5.4%), which are mainly involved in organic compound metabolism. Meanwhile, different bacteria predominate the composition of the offshore group, namely proteobacteria (71.1%) and bacteroidetes (22.0%) responsible for nitrogen and sulfur metabolism. Furthermore, their distribution pattern is shown to be spatially determined, along with a modest finding of functional diversity when comparing the bacterial species. The primary two shaping factors of bacterioplankton diversity are found to be the offshore distance and temperature. Overall, these findings add to those previously published on bacterial species and offer up functional information on the surface bacterioplankton communities in the eastern ECS. To extend our research, we propose that, in the future, it may be beneficial to monitor the dynamics of the ecosystem in this sea area.

Escherichia coli K-12 is one of the most well-studied species of bacteria. This species, however, is much more difficult to modify by homologous recombination (HR) than other model microorganisms. Research on HR in E. coli has led to a better understanding of the molecular mechanisms of HR, resulting in technical improvements and rapid progress in genome research, and allowing whole-genome mutagenesis and large-scale genome modifications. Developments using λ Red (exo, bet, and gam) and CRISPR-Cas have made E. coli as amenable to genome modification as other model microorganisms, such as Saccharomyces cerevisiae and Bacillus subtilis. This review describes the history of recombination research in E. coli, as well as improvements in techniques for genome modification by HR. This review also describes the results of large-scale genome modification of E. coli using these technologies, including DNA synthesis and assembly. In addition, this article reviews recent advances in genome modification, considers future directions, and describes problems associated with the creation of cells by design.