Surface display system of Bacillus subtilis: A promising approach for improving the stability and applications of cellobiose dehydrogenase.

Cellobiose dehydrogenase (CDH) plays a crucial role in lignocellulose degradation and bioelectrochemical industries, making it highly in demand. However, the production and purification of CDH through fungal heterologous expression methods is time-consuming, costly, and challenging. In this study, we successfully displayed Pycnoporus sanguineus CDH (psCDH) on the surface of Bacillus subtilis spores for the first time. Enzymatic characterization revealed that spore surface display enhanced the tolerance of psCDH to high temperature (80 °C) and low pH levels (3.5) compared to free psCDH. Furthermore, we found that glycerol, lactic acid, and malic acid promoted the activity of immobilized spore-displayed psCDH; glycerol has a more significant stimulating effect, increasing the activity from 16.86 ± 1.27 U/mL to 46.26 ± 3.25 U/mL. After four reuse cycles, the psCDH immobilized with spores retained 48% of its initial activity, demonstrating a substantial recovery rate. In conclusion, the spore display system, relying on cotG, enables the expression and immobilization of CDH while enhancing its resistance to adverse conditions. This system demonstrates efficient enzyme recovery and reuse. This approach provides a novel method and strategy for the immobilization and stability enhancement of CDH.

Discovery of putative inhibitors of human Pkd1 enzyme: Molecular docking, dynamics and simulation, QSAR, and MM/GBSA.

Polycystic kidney disease is the most prevalent hereditary kidney disease globally and is mainly linked to the overexpression of a gene called PKD1. To date, there is no effective treatment available for polycystic kidney disease, and the practicing treatments only provide symptomatic relief. Discovery of the compounds targeting the PKD1 gene by inhibiting its expression under the disease condition could be crucial for effective drug development. In this study, a molecular docking and molecular dynamic simulation, QSAR, and MM/GBSA-based approaches were used to determine the putative inhibitors of the Pkd1 enzyme from a library of 1379 compounds. Initially, fourteen compounds were selected based on their binding affinities with the Pkd1 enzyme using MOE and AutoDock tools. The selected drugs were further investigated to explore their properties as drug candidates and the stability of their complex formation with the Pkd1 enzyme. Based on the physicochemical and ADMET (Absorption, Distribution, Metabolism, Excretion, and Toxicity) properties, and toxicity profiling, two compounds including olsalazine and diosmetin were selected for the downstream analysis as they demonstrated the best drug-likeness properties and highest binding affinity with Pkd1 in the docking experiment. Molecular dynamic simulation using Gromacs further confirmed the stability of olsalazine and diosmetin complexes with Pkd1 and establishing interaction through strong bonding with specific residues of protein. High biological activity and binding free energies of two complexes calculated using 3D QSAR and Schrodinger module, respectively further validated our results. Therefore, the molecular docking and dynamics simulation-based in-silico approach used in this study revealed olsalazine and diosmetin as potential drug candidates to combat polycystic kidney disease by targeting Pkd1 enzyme.

Synthesis of novel metal silica nanoparticles exhibiting antimicrobial potential and applications to combat periodontitis.

Periodontitis is a severe form of gum disease caused by bacterial plaque that affects millions of people and has substantial worldwide health and economic implications. However, current clinical antiseptic and antimicrobial drug therapies are insufficient because they frequently have numerous side effects and contribute to widespread bacterial resistance. Recently, nanotechnology has shown promise in the synthesis of novel periodontal therapeutic materials. Nanoparticles are quickly replacing antibiotics in the treatment of bacterial infections, and their potential application in dentistry is immense. The alarming increases in antimicrobial resistance further emphasize the importance of exploring and utilizing nanotechnology in the fight against tooth diseases particularly periodontitis. We developed 16 different combinations of mesoporous silica nanomaterials in this study by ageing, drying, and calcining them with 11 different metals including silver, zinc, copper, gold, palladium, ruthenium, platinum, nickel, cerium, aluminium, and zirconium. The antibacterial properties of metal-doped silica were evaluated using four distinct susceptibility tests. The agar well diffusion antibacterial activity test, which measured the susceptibility of the microbes being tested, as well as the antibacterial efficacy of mesoporous silica with different silica/metal ratios, were among these studies. The growth kinetics experiment was used to investigate the efficacy of various metal-doped silica nanoparticles on microbial growth. To detect growth inhibitory effects, the colony-forming unit assay was used. Finally, MIC and MBC tests were performed to observe the inhibition of microbial biofilm formation. Our findings show that silver- and zinc-doped silica nanoparticles synthesized using the sol-gel method can be effective antimicrobial agents against periodontitis-causing microbes. This study represents the pioneering work reporting the antimicrobial properties of metal-loaded TUD-1 mesoporous silica, which could be useful in the fight against other infectious diseases too.

Immediate health risk: Concentration of heavy metals in contaminated freshwater fishes from the river channel of Turag-Tongi-Balu.

The consumption of contaminated finfish from the polluted river channel of Turag-Tongi-Balu, Kamarpara site, Dhaka poses significant health hazards to humans. We used mass spectrometry on chemically digested liquid samples from five fish species from Turag-Tongi-Balu to estimate the concentrations of 10 elements (Cr, Mn, Ni, Cu, Zn, As, Se, Cd, Fe, and Pb). Except M. vittatus, the mean concentrations of Cd, Mn, Pb, and Se exceeded the Food Safety Guideline (FSG) value in all fish species. Among the species studied, L. rohita, C. punctata, C. batrachus, H. fossilis, and M. vittatus exhibited higher Mn concentrations surpassing the FSG threshold, thus elevating the non-carcinogenic risk across all species. There were statistically significant differences (p < .05) in the mean concentrations of heavy metals among fish species. The Target Hazard Quotient (THQ) value of Mn poses a significant non-carcinogenic risk to human health, while the hazard of other metals is negligible. Except for M. vittus, the Hazard Index value (HI ≥ 1) revealed the risk that all metals exceed the limit and pose a threat to human health. Cd, As, and Ni metals pose a significant carcinogenic risk to human health from the consumption of fish samples, which is a particularly alarming target cancer risk (TCR). In conclusion, regular dietary consumption of fish from this polluted ecosystem of the Turag-Tongi-Balu River channel's Kamarpara site poses a significant health risk and is indicated as cancer. This study emphasizes the significance of monitoring heavy metal contamination in finfish and minimizing the risk to human health with effective measures.

Lignin Degradation by Klebsiella aerogenes TL3 under Anaerobic Conditions.

Lignin, the largest non-carbohydrate component of lignocellulosic biomass, is also a recalcitrant component of the plant cell wall. While the aerobic degradation mechanism of lignin has been well-documented, the anaerobic degradation mechanism is still largely elusive. In this work, a versatile facultative anaerobic lignin-degrading bacterium, Klebsiella aerogenes TL3, was isolated from a termite gut, and was found to metabolize a variety of carbon sources and produce a single kind or multiple kinds of acids. The percent degradation of alkali lignin reached 14.8% under anaerobic conditions, and could reach 17.4% in the presence of glucose within 72 h. Based on the results of infrared spectroscopy and 2D nuclear magnetic resonance analysis, it can be inferred that the anaerobic degradation of lignin may undergo the cleavage of the C-O bond (ß-O-4), as well as the C-C bond (ß-5 and ß-ß), and involve the oxidation of the side chain, demethylation, and the destruction of the aromatic ring skeleton. Although the anaerobic degradation of lignin by TL3 was slightly weaker than that under aerobic conditions, it could be further enhanced by adding glucose as an electron donor. These results may shed new light on the mechanisms of anaerobic lignin degradation.

New wheat straw fermentation feed: recombinant Schizosaccharomyces pombe efficient degradation of lignocellulose and increase feed protein.

Wheat straw contains a high amount of lignin, hindering the action of cellulase and hemicellulase enzymes, leading to difficulties in nutrient absorption by animals from straw feed. However, currently, the biological treatment of straw relies primarily on fungal degradation and cannot be directly utilized for the preparation of livestock feed. This study focuses on enzymatic co-fermentation of wheat straw to produce high-protein, low-cellulose biological feed, integrating lignin degradation with feed manufacturing, thereby simplifying the feed production process. After the optimization using Box-Behnken Design for the feed formulation, with a glucose oxidase addition of 2.46%, laccase addition of 3.4%, and malonic acid addition of 0.6%, the wheat straw feed prepared in this experiment exhibited a true protein content of 9.35%. This represented a fourfold increase compared to the non-fermented state, and the lignocellulose degradation rate of wheat straw reached 45.42%. These results not only highlight the substantial enhancement in protein content but also underscore the significant advancement in lignocellulose breakdown. This formulation significantly enhanced the palatability and nutritional value of the straw feed, contributing to the industrial development of straw feed.

Fermentation, functional analysis, and biological activities of turmeric kombucha.

BACKGROUND: Kombucha is a popular fermented drink with therapeutic benefits. The present study aimed to examine the fermentation of turmeric-infused kombucha and evaluate its biological activities and functional properties. RESULTS: The study of pH dynamics during fermentation found that turmeric kombucha has a lower pH decrease than standard kombucha, with the lowest pH of 3.1 being observed in 0.1% turmeric kombucha and the maximum pH of 3.8 found in 1% turmeric kombucha. The research shows that the symbiotic consortia of bacteria and yeast alters during the fermentation process with turmeric. Gas chromatogrphy-mass spectrometry analysis revealed that turmeric kombucha is abundant in terpenes, ketones, alcohols, aldehydes, phenols and fatty acids, with higher levels of active ingredients than regular kombucha. The kombucha with 0.6% turmeric had the highest overall acceptance score (9.0) in sensory evaluation. The total phenolic content after fermentation was in the range 0.2-0.8 mg gallic acid equivalents mL-1 . Increasing turmeric concentrations increased the antioxidant, cytotoxic and antibacterial activity of kombucha analogs, with the highest antioxidant activity (89%) observed at 0.8% turmeric, and the maximum cytotoxicity (74%) and antibacterial activity (zones of inhibition of 17.7 and 15.9 mm against Staphylococcus aureus and Escherichia coli, respectively) observed at 1% turmeric. CONCLUSION: The fermentation of kombucha infused with turmeric enhanced its biological activities, making it a healthier alternative to traditional kombucha and presenting new opportunities in the field of functional foods. Further investigations into the mechanisms underlying these effects and in vivo studies are warranted to fully comprehend the impact of turmeric kombucha consumption on human health. © 2023 Society of Chemical Industry.

Self-Assembled Microfiber-Like Biohydrogel for Ultrasensitive Whole-Cell Electrochemical Biosensing in Microdroplets.

A novel microfiber-like biohydrogel was fabricated by a facile approach relying on electroactive bacteria-induced graphene oxide reduction and confined self-assembly in a capillary tube. The microfiber-like biohydrogel (d = ∼1 mm) embedded high-density living cells and activated efficient electron exchange between cells and the conductive graphene network. Further, a miniature whole-cell electrochemical biosensing system was developed and applied for fumarate detection under -0.6 V (vs Ag/AgCl) applied potential. Taking advantage of its small size, high local cell density, and excellent electron exchange, this microfiber-like biohydrogel-based sensing system reached a linear calibration curve (R2 = 0.999) ranging from 1 nM to 10 mM. The limit of detection obtained was 0.60 nM, which was over 1300 times lower than a traditional biosensor for fumarate detection in 0.2 µL microdroplets. This work opened a new dimension for miniature whole-cell electrochemical sensing system design, which provided the possibility for bioelectrochemical detection in small volumes or three-dimensional local detection at high spatial resolutions.

Straw lignin degradation by lignin peroxidase from Irpex lacteus cooperated with enzymes and small molecules.

OBJECTIVES: Maximizing the utility value of enzymes was achieved by exploring the effects of small molecules on the efficiency of lignin degradation by lignin peroxidase. METHODS: Using wheat straw as raw material and taking lignin degradation rate as index, it was found that laccase, glucose oxidase, malonic acid, citric acid, ZnSO4, CaCl2 could promote the lignin degradation by the lignin peroxidase from Irpex lacteus, respectively. Moreover, glucose oxidase, malonic acid and CaCl2 had obvious synergy effects on lignin degradation by the lignin peroxidase. RESULTS: The optimal conditions of lignin degradation were obtained by response surface experiment: 4% glucose oxidase, 0.74% malonic acid and 3.29% CaCl2 were added for synergistic degradation at 37 â„ƒ with 50% of water content. After 72 h quickly enzymatic hydrolysis, the degradation rate of lignin was 45.84%. CONCLUSIONS: A new green and efficient method for lignin removal from straw was obtained, which provided a reference for the efficient utilization of straw and lignin peroxidase.

Ectoine Globally Hypomethylates DNA in Skin Cells and Suppresses Cancer Proliferation.

Epigenetic modifications, mainly aberrant DNA methylation, have been shown to silence the expression of genes involved in epigenetic diseases, including cancer suppression genes. Almost all conventional cancer therapeutic agents, such as the DNA hypomethylation drug 5-aza-2-deoxycytidine, have insurmountable side effects. To investigate the role of the well-known DNA protectant (ectoine) in skin cell DNA methylation and cancer cell proliferation, comprehensive methylome sequence analysis, 5-methyl cytosine (5mC) analysis, proliferation and tumorigenicity assays, and DNA epigenetic modifications-related gene analysis were performed. The results showed that extended ectoine treatment globally hypomethylated DNA in skin cells, especially in the CpG island (CGIs) element, and 5mC percentage was significantly reduced. Moreover, ectoine mildly inhibited skin cell proliferation and did not induce tumorigenicity in HaCaT cells injected into athymic nude mice. HaCaT cells treated with ectoine for 24 weeks modulated the mRNA expression levels of Dnmt1, Dnmt3a, Dnmt3b, Dnmt3l, Hdac1, Hdac2, Kdm3a, Mettl3, Mettl14, Snrpn, and Mest. Overall, ectoine mildly demethylates DNA in skin cells, modulates the expression of epigenetic modification-related genes, and reduces cell proliferation. This evidence suggests that ectoine is a potential anti-aging agent that prevents DNA hypermethylation and subsequently activates cancer-suppressing genes.

Strategies for efficient management of microplastics to achieve life cycle assessment and circular economy.

The anticipated increase in the influx of plastic waste into aquatic environments has propelled the identification and elimination of plastic waste into the global agenda. The plastics sector generates a significant volume of materials, which, due to their extended durability, accumulate rapidly in natural ecosystems. Consequently, this indiscriminate utilization, along with the deposition of plastic waste (PW) in landfills and inadequate recycling practices, leads to diverse economic, social, and environmental consequences. Microplastics (MPs) are a type of PW that has been fragmented into particles measuring less than 5 mm. These particles have been found in several environments, including the air, soil, freshwater, and ocean ecosystems, where they accumulate in large quantities. In order to gain insight into the ecological risks and resource implications associated with a plastic product, it is strongly advised to conduct life cycle and sustainability analyses. Therefore, this paper examines various strategies aimed at achieving effective management of MP waste in order to develop a conceptual framework for MPs in circular economy and life cycle assessment (LCA). The findings of this study provides a new avenue for future research and contribution to manage MP waste as well as reduce their environmentally hazardous impact.

Arabinan hydrolysis by GH43 enzymes of Hungateiclostridium clariflavum and the potential synergistic mechanisms.

Glycoside hydrolase family 43 (GH43) represents a major source of arabinan- and arabinoxylan-active enzymes. Interestingly, some microbes remarkably enriched GH genes of this family, with the reason unknown. Hungateiclostridium clariflavum DSM 19,732 is an efficient lignocellulose degrader, which harbors up to 7 GH43 genes in its genome. We cloned three of the seven GH43 genes, and found that Abn43A is a unique endoarabinanase, which unprecedently showed approximately two times larger activity on sugar beet arabinan (116.8 U/mg) than that on linear arabinan, and it is efficient in arabinooligosaccharide production. Abn43B is an exoarabinanase which directly releases arabinose from linear arabinan. Abn43C is an α-L-arabinofuranosidase which is capable of splitting the arabinose side-chains from arabinooligosaccharides, arabinoxylooligosaccharides, and arabinoxylan. Most importantly, the three GH43 enzymes synergized in hydrolyzing arabinan. Compared to Abn43B alone, a supplement of Abn43A increased the arabinose production from linear arabinan by 150%, reaching 0.44 g/g arabinan. Moreover, an addition of Abn43C to Abn43A and Abn43B boosted the arabinose production from sugar beet arabinan by 15 times, reaching 0.262 g/g arabinan. Our work suggested the intensified functions of multiple GH43 enzymes toward arabinan degradation in H. clariflavum, and a potential synergetic mechanism among the three GH43 enzymes is suggested. KEY POINTS: • Endoarabinanase GH43A prefers branched substrate to linear one • Exoarabinanase GH43B can directly release arabinose from linear arabinan • The three GH43 enzymes synergized in arabinan hydrolysis.

Pullulanibacillus camelliae sp. nov., isolated from Pu'er tea.

A novel Gram-stain-positive, strictly aerobic, endospore-forming, rod-shaped bacterial strain 7578-24T was isolated from ripened Pu'er tea. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain 7578-24T clustered with species of the genus Pullulanibacillus in the family Sporolactobacillaceae with 97.8-95.2 % sequence similarities, and was most closely related to Pullulanibacillus pueri YN3T with 97.8 % 16S rRNA gene sequence similarity. The DNA-DNA relatedness value between strain 7578-24T and P. pueri YN3T was 35 %. Strain 7578-24T had a cell-wall type A1γ peptidoglycan with meso-diaminopimelic acid as the diagnostic diamino acid. The major menaquinone was menaquinone 7 (MK-7). C18 : 1ω7c (45.4 %), anteiso-C17 : 0 (30.6 %) and anteiso-C15 : 0 (10.1 %) were the predominant fatty acids, and diphosphatidylglycerol, phosphatidylglycerol, five unknown phospholipids and one unknown aminolipid were the major polar lipids. The DNA G+C content of strain 7578-24T was 45.2 mol%. Strain 7578-24T could be differentiated from other related species of the genus Pullulanibacillus based on phenotypic characteristics, chemotaxonomic differences, phylogenetic analysis and DNA-DNA hybridization data. On the basis of polyphasic evidence from this study, a novel species of the genus Pullulanibacillus named Pullulanibacillus camelliae sp. nov. is proposed, with strain 7578-24T (=CGMCC 1.15371T=JCM 31236T) as the type strain.

Bacillus ectoiniformans sp. nov., a halotolerant bacterium isolated from deep-sea sediments.

A halotolerant, Gram-positive bacterium (strain NE-14T), which was isolated from sediment samples of the South China Sea, was subjected to a taxonomic study. Strain NE-14T grew well at wide temperature and pH ranges, 10.0-45.0 °C and pH 6-10, with an optimum at 30 °C and pH 8.0, respectively. Growth of strain NE-14T was observed at total salt concentrations of 0-10 % (w/v) with optimum at 2 % (w/v). Phylogenetic analysis based on 16S rRNA gene sequence comparison indicated that the isolate belongs to the genus Bacillus. Strain NE-14T was related most closely to Bacillus shackletonii LMG 18435T, Bacillus bataviensis LMG 21833T, Bacillus idriensis SMC 4352-2T and Bacillus drentensis LMG 21831T with 16S rRNA gene sequence similarities of 96.2, 95.9, 95.8 and 95.7 %, respectively. DNA-DNA hybridization between strain NE-14T and B. shackletonii LMG 18435T, B. bataviensis LMG 21833T, B. idriensis SMC 4352-2T and B. drentensis LMG 21831T gave reassociation values of about 27.4, 22.4, 16.4 and 15.9 %, respectively. The DNA G+C content of strain NE-14T was 39.2 mol%. The predominant isoprenoid quinone was menaquinone 7 (MK-7). The cell-wall peptidoglycan contained meso-diaminopimelic acid as the diagnostic diamino acid. The predominant cellular fatty acids of strain NE-14T were iso-C15 : 0 and anteiso-C15 : 0. The major polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol and phospholipid. Based on the phenotypic and phylogenetic characteristics, it is proposed that strain NE-14T be classified as representing a novel species of the genus Bacillus, for which the name Bacillus ectoiniformans sp. nov. is proposed. The type strain is NE-14T ( = DSM 28970T = JCM 30397T).

Description of Leucobacter holotrichiae sp. nov., isolated from the gut of Holotrichia oblita larvae.

A Gram-stain-positive bacterium, designated T14T, was isolated from the gut of Holotrichia oblita larvae and was subjected to a taxonomic study. The isolate was rod-shaped, aerobic, non-motile, non-spore-forming and yellow-pigmented. Phylogenetic analysis based on 16S rRNA gene sequence comparison indicated that the isolate is related to the genus Leucobacter. Its closest neighbours were the type strains 'Leucobacter kyeonggiensis' F3-P9 (96.8% 16S rRNA gene sequence similarity), Leucobacter celer NAL101T (96.2%) and Leucobacter chironomi DSM 19883T (95.5%). The DNA G+C content of strain T14T was 69.3 mol%, and DNA-DNA hybridization values with closely related strains were <32%. The predominant cellular fatty acids were anteiso-C15:0 (49.3%), iso-C16:0 (16.4%) and anteiso-C17:0 (16.8%). The major polar lipids were aminolipid, diphosphatidylglycerol, phosphatidylglycerol, phospholipid, phosphoglycolipid and unidentified glycolipids. The predominant respiratory quinone was MK-11. Based on these phylogenetic and phenotypic results, strain T14T can be clearly distinguished from all of the recognized species of the genus Leucobacter and is considered to represent a novel species of the genus Leucobacter. The name Leucobacter holotrichiae sp. nov. is proposed, with the type strain T14T (=DSM 28968T=JCM 30245T).

Pullulanibacillus pueri sp. nov., isolated from Pu'er tea.

A novel Gram-stain-positive, aerobic, endospore-forming, rod-shaped bacterial strain YN3(T) was isolated from ripened Pu'er tea. Phylogenetic analysis of 16S rRNA gene sequences showed that the strain belonged to the family Sporolactobacillaceae and was closely related to Pullulanibacillus naganoensis DSM 10191(T) (95.8% 16S rRNA gene sequence similarity) and Pullulanibacillus uraniitolerans DSM 19429(T) (95.4%). Growth of the strain was observed at 20-50 °C (optimum 30-37 °C), at pH 4.0-8.0 (optimum pH 5.0-6.0). The strain had a cell-wall type A1γ peptidoglycan with meso-diaminopimelic acid as the diagnostic diamino acid. The predominant menaquinone was menaquinone-7 (MK-7). The major fatty acids were anteiso-C15:0, anteiso-C17:0 and C18:1ω7c. The DNA G+C content of strain YN3(T) was 38.7 mol%. Strain YN3(T) could be differentiated from recognized species of the genus Pullulanibacillus based on phenotypic characteristics, chemotaxonomic differences, phylogenetic analysis and DNA-DNA hybridization data. On the basis of polyphasic evidence from this study, Pullulanibacilluspueri sp. nov., is proposed, with strain YN3(T) ( = CGMCC 1.12777(T ) = JCM 30075(T)) as the type strain.

Description of Comamonas serinivorans sp. nov., isolated from wheat straw compost.

A Gram-stain-negative bacterium, designated SP-35(T), was isolated from compost and was subjected to a taxonomic study. This isolate was short-rod-shaped and non-spore-forming. Phylogenetic analysis based on 16S rRNA sequence comparison indicated the isolate was related to the genus Comamonas. 16S rRNA gene sequence analysis showed that its closest neighbours were the type strains Comamonas odontotermitis Dant 3-8(T) (96.8 % similarity), Comamonas testosteroni DSM 50244(T) (96.5 %), Comamonas guangdongensis CY01(T) (95.9 %) and Comamonas composti YY287(T) (95.6 %). Using phylogenetic analysis, DNA-DNA hybridization, fatty acid composition data and a range of physiological and biochemical characteristics we could clearly distinguish strain SP-35(T) from type strains of the genus Comamonas. The genomic DNA G+C content of strain SP-35(T) was 63.1 mol%. The predominant cellular fatty acids were C16 : 0, C17 : 0 cyclo, summed feature 3 (C16 : 1ω6c and/or C16 : 1ω7c) and summed feature 8 (C18 : 1ω6c and/or C18 : 1ω7c). The major polar lipids were diphosphatidylglycerol, phosphatidylethanolamine and phosphatidlyglycerol. Differences in phenotypic and phylogenetic characteristics support the classification of strain SP-35(T) as a representative of a novel species in the genus Comamonas, for which the name Comamonas serinivorans sp. nov. is proposed. The type strain is SP-35(T) ( = DSM 26136(T) = JCM 18194(T)).

Bacillus ligniniphilus sp. nov., an alkaliphilic and halotolerant bacterium isolated from sediments of the South China Sea.

An alkaliphilic and halotolerant Gram-stain-positive bacterium, which was isolated from sediment samples from the South China Sea, was subjected to a taxonomic study. The isolate, strain L1T, grew well at a wide range of temperatures and pH values, 10.0-45.0 °C and pH 6-11, with optima at 30 °C and pH 9.0, respectively. The growth of strain L1T occurred at total salt concentrations of 0-10% (w/v) with an optimum at 2% (w/v). Phylogenetic analysis based on 16S rRNA sequence comparison indicated that the isolate represented a member of the genus Bacillus. The strains most closely related to strain L1T were Bacillus nanhaiisediminis JCM 16507T, Bacillus halodurans DSM 497T and Bacillus pseudofirmus DSM 8715T, with 16S rRNA similarities of 96.5%, 95.9% and 95.7%, respectively. DNA-DNA hybridization of strain L1T with the type strains of the most closely related species, B. nanhaiisediminis JCM 16507T, B. halodurans DSM 497T and B. pseudofirmus DSM 8715T, showed reassociation values of about 21.7%, 14.3% and 13.9%, respectively. The DNA G+C content of strain L1T was 40.76 mol%. The predominant isoprenoid quinone was menaquinone 7 (MK-7). The cell-wall peptidoglycan contained meso-diaminopimelic acid as the diagnostic diamino acid. The predominant cellular fatty acids of strain L1T were iso-C14 : 0 and anteiso-C15:0. The major polar lipids were diphosphatidylglycerol, phosphatidylethanolamine and phosphatidylglycerol. Based on the phenotypic and phylogenetic characteristics, it is proposed that strain L1T (=JCM 18543T=DSM 26145T) should be classified as the type strain of Bacillus ligniniphilus sp. nov.

Microbiological quality and characteristics of probiotic products in China.

BACKGROUND: Probiotics are widely used in the food industry and medicine fields in China, but few studies have been conducted to evaluate the actual microbial amounts and species in probiotic products, which may conflict with the labels and mislead consumers to choose inappropriate foods or medicines. RESULTS: Twenty commercial dairy products and eight commercial 'healthcare' samples were collected from markets in China and tested using culture-dependent and culture-independent methods. The results suggested that the total bacterial counts of most commercial products met the minimum quantitative requirement of the Chinese national standard (6.00 log colony-forming units g(-1) ). However, the bacterial counts of specific species were inconsistent with the labelling. In parallel, denaturing gradient gel electrophoresis analysis indicated that some probiotic-containing products were wrongly labelled; no Bifidobacterium species were detected in the products claiming to contain bifidobacteria, and the probiotic characteristics (antimicrobial activity, acid resistance and bile resistance) of some isolates had degraded. Moreover, some contaminating bacteria, e.g. Enterobacter sp., Klebsiella sp. and Serratia sp., were also detected in these products. CONCLUSION: The combination of culture-dependent and culture-independent methods was proven to quickly and conveniently detect the microbial diversity in probiotic products, and more effort is required to regulate the probiotic market in China.

Advancements in bacterial chemotaxis: Utilizing the navigational intelligence of bacteria and its practical applications.

The fascinating world of microscopic life unveils a captivating spectacle as bacteria effortlessly maneuver through their surroundings with astonishing accuracy, guided by the intricate mechanism of chemotaxis. This review explores the complex mechanisms behind this behavior, analyzing the flagellum as the driving force and unraveling the intricate signaling pathways that govern its movement. We delve into the hidden costs and benefits of this intricate skill, analyzing its potential to propagate antibiotic resistance gene while shedding light on its vital role in plant colonization and beneficial symbiosis. We explore the realm of human intervention, considering strategies to manipulate bacterial chemotaxis for various applications, including nutrient cycling, algal bloom and biofilm formation. This review explores the wide range of applications for bacterial capabilities, from targeted drug delivery in medicine to bioremediation and disease control in the environment. Ultimately, through unraveling the intricacies of bacterial movement, we can enhance our comprehension of the intricate web of life on our planet. This knowledge opens up avenues for progress in fields such as medicine, agriculture, and environmental conservation.