Bacterial cellulose, a natural biopolymer with higher purity and better mechanical properties than plant cellulose, is expected to be widely used as a new green polymer material. A variety of bacteria have now been proven to have the ability to produce cellulose, in which bacterial cellulose synthase plays a crucial role. Therefore, understanding the catalysis mechanism of bacterial cellulose synthase is a key to the mass production and broad utilization of bacterial cellulose. This paper reviews the basic properties of bacterial cellulose synthase, including the screening of strains, the enhancement of yield, and the cellular localization of the synthase, aiming to promote the research on the catalysis mechanism of cellulose synthase. Further, based on the mechanism of cellulose synthase, this paper detail the influencing factors ofin vitro synthesis and review the research progress in the roles of each subunit of this synthesis method. We explore the catalysis mechanism of bacterial cellulose synthase, point out the problems in the current research, and envision the future research directions in this field, with a view to providing a theoretical basis for the large-scale application of bacterial cellulose by deciphering the synthesis mechanism.

Urothelial carcinoma of bladder (UCB) is a common malignant tumor of the urinary system and a common pathological type of bladder cancer (BC). With high morbidity, high mortality, and easy recurrence, UCB poses a serious threat to human health. The occurrence of UCB may be associated with smoking and exposure to toxic chemicals. With the deepening of research, researchers have discovered unique microbiota related to the occurrence and development of UCB in the bladder. This review focuses on the involvement of microbiota in the occurrence and development of UCB through urinary tract infection (UTI), affecting epithelial-mesenchymal transition (EMT), and up-regulating the expression of programmed cell death 1 ligand 1 (PD-L1). At the same time, this paper introduces the microbiota characteristics of healthy people and UCB patients as well as the prevention and treatment of UCB. By reviewing the relationship between microbiota and UCB, this paper provides new ideas for further clarifying the promoting effect of microbiota on UCB and developing drugs for treating UCB.

Nattokinase has a variety of physiological functions and serves the treatment of cardiovascular diseases. Menaquinone-7, one of indispensable fat-soluble vitamins in the human body, can prevent diseases such as osteoporosis and Parkinson's disease. [Objective] To enhance the co-production of nattokinase and menaquinone-7 byBacillus subtilis, reveal the co-production mechanism in the recombinant strain, and provide new metabolic engineering strategies for the production of nattokinase and menaquinone-7. [Methods] We constructedB.subtilis 168-ΔbdhA by knocking out the 2,3-butanediol dehydrogenase genebdhA fromB.subtilis 168. RNA-seq was employed to measure the expression changes of key enzyme-coding genes in the nattokinase and menaquinone-7 synthesis pathways. [Results] Compared withB.subtilis 168, the content of 2,3-butanediol inB.subtilis 168-ΔbdhA was 2.76 g/L, which was reduced by 64.0%. The yields of nattokinase and menaquinone-7 were increased by 30.0% and 60.0%, respectively. The expression levels of genes related to central carbon metabolism, oxidative phosphorylation, and the synthesis of nattokinase and menaquinone-7 changed by RNA-seq analysis. The expression level of nattokinase negative regulator genecodY was down-regulated by 2.19-fold in the mutant. The expression ofsecA,tatAD, andtatC involved in protein secretion showed the down-regulation of 0.37-fold, up-regulation of 2.81-fold, and up-regulation of 0.50-fold, respectively. [Conclusion] The knockout ofbdhA blocked the carbon flux of 2,3-butanediol and promoted glycerol uptake, causing more carbon fluxing to the synthesis pathways of nattokinase and menaquinone-7. The down-regulation of the negative regulatorcodY promoted the transcription of nattokinase. The up- and down-regulation of genes involved in protein scretion promoted extracellular secretion of menaquinone-7.

[Objective] To clarify the promotion effects of different organic compounds on the formation of magnetosomes inAcidithiobacillus ferrooxidans BYM, so as to provide a new idea for safely and effectively improving the magnetosome yield. [Methods] Single-factor experiments were conducted to measure the effects of ten organic compounds on the ferrous oxidation ofA.ferrooxidans BYM, and the organic compounds promoting the synthesis of magnetosomes were further screened by a 4 L fermentation system. The classical kinetic models (Logistic, Luedeking-Piret, and substrate consumption kinetic equations) were employed to build the kinetic models for the growth, magnetosome synthesis, and ferrous consumption ofA.ferrooxidans BYM by batch fermentation experiments. [Results] The maximum magnetosome yield (2.00×10⁻³ g/L) was achieved with the addition of 10 mmol/L gluconic acid, in the presence of which the bacterial cells were oval and had a smooth surface. With the addition of gluconic acid, the fermentation kinetics ofA.ferrooxidans BYM was in accordance with Logistic, Luedeking-Piret, and substrate consumption kinetic equations. [Conclusion] The addition of 10 mmol/L gluconic acid increases the magnetosome yield ofA.ferrooxidans BYM by eight times. Gluconic acid changes the cell morphology and surface ofA.ferrooxidans BYM. The kinetics models of cell growth, product formation, and substrate consumption can illustrate the batch fermentation ofA.ferrooxidans BYM in the presence of gluconic acid.

[Background] Yuncheng Salt Lake is a high-salt environment with intensive human activities. The community structure and ecological diversity of bacteria in Yuncheng Salt Lake are similar to those in other salt lakes while having their particularities. [Objective] Yuncheng Salt Lake is rich in color and harbors abundant halophilic and salt-tolerant microorganisms. To understand the distribution of bacterial resources in Yuncheng Salt Lake, we measured the bacterial diversity and community structures in different areas of this lake. [Methods] We employed 16S rRNA gene amplicon sequencing to study the community structures of halophiles in different areas of Yuncheng Salt Lake and predicted the potential metabolic functions of the bacteria. [Results] The dominant bacteria varied in different areas of Yuncheng Salt Lake. Specifically,Pseudomonadota,Actinobacteriota, andBacteroidota were dominant in the central lake,Bacillota in the eastern lake, andPatescibacteria in the western lake. The bacterial diversity in the central lake area with light yellow water was significantly higher than that in the eastern and western lake. However, the bacterial diversity was low in the central lake area with red water. This result indicated that the bacterial distribution was different in the central lake areas with different water colors the metabolic pathway activity of bacteria in the salt lake and strong regional distribution. The microbial metabolism in the east and west lake was more active than that in the lake. [Conclusion] Bacteria show high diversity in Yuncheng Salt Lake. The environment in different of lake influence the community structure of bacteria. This study provides a theoretical basis for the diversity conservation, development, and utilization of the bacterial resources in Yuncheng Salt Lake.

[Objective] Methane-oxidizing bacteria (MOB) are crucial indicators in the microbial exploration of oil and gas reservoirs, while their diversity and distribution are influenced by geographical location and environmental factors. This study aims to explore the effects of environmental variations on the abundance and distribution of MOB in the soil samples collected from seven representative areas in typical oil and gas reservoirs. [Methods] Soil samples were subjected to real-time fluorescence quantitative PCR (qPCR) forpmoA and sequencing of bacterial 16S rRNA gene andpmoA. The abundance of MOB was compared among different samples, on the basis of which the impacts of environmental factors on the distribution of MOB were analyzed. [Results] The highest water content (approximately 22.8%) was detected in the samples from the Jianghan Basin. The average content of nitrate nitrogen was highest in the Yubei oil field, reaching approximately 31.96 μg/g. The Chunguang oil field showcased the highest concentrations of SO₄²⁻ (6 425.0 mg/g) and Cl⁻ (1 617.0 mg/g). The qPCR results revealed that thepmoA in MOB accounted for only 0.77% of that in total soil bacteria, indicating the low absolute abundance of MOB in the soil. The 16S rRNA gene sequencing identified three type Ⅰ MOB genera (Methylosarcina,Methylocaldum, andMethylococcus) and one type Ⅱ MOB genera (Methylocystis). However, the dominant genera in the MOB had extremely low relative abundance, with the maximum of 0.124%. Sequencing ofpmoA revealed thatMethylocystis andMethylosinus, two genera of type Ⅱ MOB, were dominant. The absolute abundance of MOB showed significant correlations with ammonium nitrogen, pH, particle size, SO₄²⁻, and Cl⁻. The relative abundance of MOB had significant correlations only with particle size, total nitrogen, total phosphorus, and metal ions (Al, Fe, K, Ca, Mg, Mn, Zn, and Cu). The discriminant correlation analysis (DCA) indicated that soil moisture, pH, soil particles<2 μm, total nitrogen, and Ca²⁺ significantly influenced the composition of the functional genepmoA in MOB. [Conclusion] This study analyzed the absolute and relative abundance of MOB in soil samples from seven typical oil and gas reservoirs. The MOB abundance showed significant differences depending on the measurement method used. The 16S rRNA gene sequencing fails to comprehensively reflect the community structure of MOB in the soil samples. Different geographical locations showed variations in MOB communities, and no specific indicator communities were detected for oil and gas reservoirs or background sites on a national scale. The correlation analysis between environmental factors and MOB revealed that the environmental factors had different effects on the absolute and relative abundance of MOB.

[Objective] To detail the molecular evolution and ecological adaptation ofPseudoalteromonas arabiensis. [Methods] Illumina HiSeq X Ten and Oxford Nanopore PromethION were used for the whole genome sequencing ofPseudoalteromonas arabiensis N1230-9 isolated from the surface seawater of the Pacific Ocean. Bioinformatics tools were used to assemble and annotate the original sequencing data, and the type strainPseudoalteromonas arabiensis JCM 17292 was used for comparative genomic analysis. [Results] The genome of strain N1230-9 consisted of two chromosomes, with a size of 4 627 470 bp and the G+C content of 40.85%, encoding a total of 4 202 proteins. Genome annotation showed that strain N1230-9 carried functional genes contributing to the adaption to the marine environment. These genes were mainly involved in heavy metal resistance, iron-uptake systems, anti-phage defense systems, hydrolytic enzymes, carbohydrate metabolism, and two-component signaling systems. Comparative genomic analysis revealed that strain N1230-9 and strain JCM 17292 possessed unique genes conferring adaption to different ecological niches. These genes were primarily involved in heme uptake, heavy metal resistance, anti-phage defense, two-component signaling, and horizontal gene transfer. [Conclusion] P. arabiensis N1230-9 isolated from surface seawater has evolved unique genes for adaption to its ecological niche.

Anabaena azotica, as a photoautotrophic microorganism, has good carbon and nitrogen sequestration abilities. The application ofA.azotica could improve soil fertility and reduce the application of chemical fertilizers. However, the mechanism of carbon and nitrogen sequestration in soil byA.azotica and the sequestration efficiency of different strains remain to be studied. Therefore, it is important to screenA.azotica strains and probe into the processes of C and N sequestration in soil by the strains at the single-cell level. In view of the complex and dynamic process of element changes inA.azotica at the single-cell level, this study introduced the carbon and nitrogen sequestration process in soil byA.azotica. In addition, we expounded the principle, progress, and difficulties of using nano-secondary ion mass spectrometry combined with stable isotopic probing (NanoSIMS-SIP) and Raman spectroscopy imaging combined with stable isotopic probing (Raman-SIP) to analyze the spatiotemporal distribution of carbon and nitrogen at the single-cell level. This review focuses on the latest technological development and application of single-cell stable isotope technology for quantitative visualization of carbon and nitrogen sequestration inA.azotica. At the same time, future research on the visualization technology is prospected. This review is of great scientific significance for understanding the mechanism of carbon and nitrogen sequestration and the difference in nitrogen fixation efficiency of differentA.azotica strains in soil. It provides a theoretical basis for reducing the use of chemical fertilizers and improving soil fertility in agricultural production.

[Objective] Bio-inspired artificial mineral shells are used to protect living bacterial cells. [Methods] Bacterial cells were encapsulated in firm and intact mineral shells, where the limited physical space and substance exchange induced the dormancy of living bacteria to decrease the viability loss during long-term preservation and even in extreme environments. Moreover, acids can erode the shells to reactivate the bacteria. [Results] Compared with the un-mineralization treatment (EcN), the mineralization treatment (EcN@CaCO₃) increased the bacterial viability by a maximum of 262 folds in a 32-day storage experiment and the survival rate by 837, 171, 59.1, and 729.7 folds at pH 2.5, pH 12.0, 80 ℃, and in the presence of an antibiotic, respectively. [Conclusion] We employed biomimetic mineralization to improve the stability of bacterial cells in storage, which can provide a research basis for the application of microorganisms in environmental engineering, food production, and biomedical engineering.

[Objective] To isolate efficient phosphorus-solubilizing strains from soils in the permafrost region of the Qinghai-Xizang Plateau and provide strain resources for the activation of unavailable phosphorus in the soil of the Plateau. [Methods] The selective media with organic and inorganic phosphorus were used to isolate phosphorus-solubilizing strains from the soil samples collected in the permafrost region around the Tanggula Pass of the Qinghai-Xizang Plateau by the plate streaking method. The phylogenetic tree was built based on the 16S rRNA gene sequences to identify the strains, and then the phosphorus-solubilizing abilities and stress tolerance of the strains were determined. [Results] Five strains belonging toPseudomonas were isolated, including three inorganic phosphorus-solubilizing strains (i5, i6, and i9L) and two organic phosphorus-solubilizing strains (Qb and Qo). After 7 days of incubation in shake flasks at 30 ℃, the content of available phosphorus in the supernatants of Qb and Qo was 534.8 mg/L and 723.7 mg/L, respectively, which was significantly higher than that (166.9–210.5 mg/L) in the supernatants of i5, i6, and i9L. The available phosphorus content in the supernatant of Qo was the highest (519.7–683.0 mg/L) among the five isolates under different concentrations of PEG6000. The phosphorus-solubilizing abilities of Qb and Qo were stronger than those of the other strains at 5 ℃ and 10 ℃. [Conclusion] Qo outperformed the other strains in terms of tolerance to low temperature and drought stress, serving the development of microbial fertilizers and vegetation restoration in alpine regions such as the Qinghai-Xizang Plateau.