Polycyclic aromatic hydrocarbons (PAHs) are widely distributed in the environment and have ecological and environmental toxicological effects. Therefore, the treatment and remediation of PAH-contaminated sites have attracted much attention. Microbial degradation, as one of the remediation methods for PAH pollution, has the advantages of low cost, high efficiency, and environmental friendliness. The co-cultured microbial system usually has better degradation effect, stronger adaptability, and greater resistance to stress than single strains. This paper reviews the microbial species and mechanisms of co-cultured microorganisms for degrading PAHs and points out the strategies for constructing co-culture systems and different microbial combinations, hoping to provide reference for the application of co-cultured microbial flora in the remediation of organically polluted environments.

The toxin-antitoxin (TA) system is ubiquitous in bacteria and archaea. A typical TA system generally consists of a toxin that inhibits bacterial growth and an antitoxin that neutralizes toxin toxicity. At present, TA systems are classified into types I-VIII, of which type II system is the most extensively studied. In addition, researchers have found that there are atypical TA systems such as monocistronic TA systems and three-component TA systems. After the discovery of the first TA system (CcdB/CcdA) in the 1980s, TA systems have been shown to play a key role in the physiological processes of microorganisms. In this paper, we review the research results about the roles of TA systems in resisting bacteriophage infections in recent years and summarize the neutralization mechanisms. In particular, we brief how TA systems specifically sense the invading bacteriophages and the underlying molecular mechanisms, aiming to provide reference for the research on the roles and regulation mechanisms of unknown TA systems in the future.

Interactions between microbial symbionts and insects are essential for the growth, development, and reproduction of insects. This review focuses on how microbial symbionts regulate lipid metabolism in insects via signaling pathways. Microbial symbionts affect lipid metabolism in insects through a variety of mechanisms. Microbial symbionts provide lipids or lipid precursors such as steroids to their insect hosts. Microbial symbionts can also modulate host insulin signaling pathway by producing short-chain fatty acids or activating immune signaling pathways, thereby changing the lipid content of insects. In addition, microbial symbionts can activate target of rapamycin and adipokinetic hormone signaling pathways to regulate lipid metabolism in insects. Further research in the similarities and differences of these signaling pathways in different insect species is of great significance for comprehension of insect ecological adaptability and reproductive strategies, and development of new pest management strategies.

Succinic acid is an important four-carbon dicarboxylic acid widely used in the food, pharmaceutical, and chemical industries. Compared with petrochemical-based chemical synthesis methods, microbial fermentation offers an economical and environmentally friendly alternative for succinic acid production, presenting significant potential for industrial applications. Due to the robust environmental tolerance, yeast cell factories for succinic acid production have gradually become a research focus. This review centers on succinic acid production in yeast, providing an overview of metabolic engineering and regulatory strategies for constructing yeast cell factories. The research hotspots in this field include the development of succinic acid biosynthetic pathways, optimization of cofactor supply, and modification of transmembrane transport systems. Additionally, recent advances in cost-effective succinic acid biosynthesis and approaches to enhance yeast strain robustness are discussed. Finally, the review provides the prospects of yeast in succinic acid biosynthesis.

Lactic acid bacteria (LAB) have extensive applications in food and medicine fields. They are used as starters and functional probiotics in food fermentation. The activity and performance of LAB are influenced by various environmental stresses involving osmotic pressure, temperature, oxygen, acidity, and bile salts. Edible LAB can provide numerous health benefits. However, their viable counts decrease during production, storage, and digestion. This paper systematically discusses the different stressful environments faced by LAB during production, storage, and digestion, as well as their stress responses. Furthermore, this paper summarizes existing high activity protection strategies and mechanisms from two aspects: isolating from stressful environments and enhancing strain resistance. This review aims to provide theoretical support for LAB strain engineering and product development.

Kinases are the major category of proteins that regulate intracellular signal transduction by phosphorylating target proteins. They catalyze the transfer of phosphate groups of high-energy donor molecules to specific substrates, serving as the key regulators of cell functions. Host kinases constitute a large protein family with diverse functions, guiding the activation, subcellular localization, and conformational changes of target proteins. In recent years, more and more studies have shown that host kinases play a regulatory role in the processes of picornavirus infections. Picornaviruses can cause a variety of diseases in human and animals. They lead to serious public health problems and huge economic burden in a global scope. A comprehensive understanding of the infection processes of picornaviruses is helpful for the prevention and treatment of these diseases. This paper reviews the research progress in the regulation of picornavirus infections by host kinases, aiming to comprehensively elucidate the mechanisms for interactions between host kinases and picornaviruses. At the same time, we discuss the potential of host kinases as effective treatments and drug targets against picornaviruses infection, aiming to provide implications for the development of new anti-picornavirus agents and vaccines in the future.

The fermentation, morphological observation, and metabolite purification of mycelial pellets and the application of mycelial pellets in sewage treatment and energy recovery have gained widespread attention from researchers in the fields of environment and biology. To get a full picture of the research hotspots and trends of mycelial pellets. We screened 1 337 scientific articles related to the application of mycelial pellets that were published in the past 20 years from the Web of Science. The clustering and temporal trends of keywords and the co-occurrence of countries, authors or institutions were visually analyzed. The annual number of published articles was on the rise, involving a total of 97 topics, and interdisciplinary articles were abundant and tended to have higher cited frequency. China's achievements in this field kept a leading position and China maintained close cooperation with other countries. The hot keywords remained stable (growth, morphology, fermentation, removal, degradation, mycelial pellets, biological control, fungi, culture, optimization, biodegradation, and biosorption), and the uptrending and emerging keywords changed in recent years. The application of mycelial pellets in water treatment had been increasingly studied, with the related keywords (waste water, performance) becoming increasingly frequent. Emerging keywords related to wastewater treatment with mycelial pellets as carriers (biomass, bacteria), synthesis by mycelial pellets (biosynthesis), and water treatment with both mycelial pellets and algae (Chlorella vulgaris, microalgae) remained hot. This result indicates that research on the application of mycelial pellets in water treatment has gradually evolved into more systematic research directions, which will become future research hotspots and opportunities.

[Objective] In view of the difficulty in the culture of chemoautotrophic bacteria, this study analyzed the reasons for the difficulty based on the theory of electron distribution and explored the feasibility of using the electron distribution strategy for increasing the biomass of chemoautotrophic bacteria based on pure culture. [Methods] From the perspective of maintaining intracellular pH balance and optimal energy metabolism, we calculated the optimal distribution ratios of electrons produced by the sulfur-oxidizing bacterial strain Halothiobacillus sp. DCM-3, nitrite-oxidizing bacterial strain Nitrobacter sp. N1, and ammonia-oxidizing bacterial strain Nitrosomonas sp. SCUT-1 to O₂ and CO₂ by oxidizing corresponding substrates. Furthermore, different molar ratios of O₂ to HCO₃^- (CO₂) were set respectively to form different electron distribution ratios for pure culture verification of the strains. Substrate and product concentrations were measured by ion chromatography and ultraviolet spectrophotometry, and cell density was measured by the dilution coating method. [Results] The optimal electron distribution ratios of strains DCM-3, N1, and SCUT-1 were 0.733:0.267, 0.867:0.133, and 0.6:0.4, respectively. Based on the optimal electron distribution ratios, strains DCM-3, N1, and SCUT-1 could synthesize 3.967 ATP/S₂O₃^2-, 0.433 ATP/NO₂^-, and 1.35 ATP/NH₃, respectively. According to the calculation results, the main reasons for the difficulty in culture were the small amount of ATP synthesized with the energy provided by per unit substrate and the need to control a low oxygen concentration and supplement an appropriate amount of inorganic carbon. The results of pure culture verification showed that the biomass of DCM-3 under the optimal ratio was 6.5×10⁷ CFU/mL, which was 2.2 times that of the control group. The biomass of N1 under the optimal ratio was 7×10⁶ CFU/mL, which was not significantly different from that of the control group. However, the HCO₃^- concentration (0.4 mmol/L) of the optimal ratio of strain N1 was significantly lower than that (2.5 mmol/L) of the control group, which meant that the strain showed a growth characteristic of tending to higher oxygen concentration but lower CO₂ demand, which was consistent with the calculated optimal ratio. The biomass accumulation per unit NH₄⁺ concentration of SCUT-1 strain in the group with controlled O₂ and CO₂ was more than 1.3×10⁶ CFU/(mL·(mmol/L)), which was 25%-40% higher than that obtained under sufficient O₂ and CO₂. [Conclusion] The culture strategy of chemoautotrophic bacteria based on electron distribution restricts the culture conditions of electron distribution by limiting the molar amounts and forming a certain ratio of O₂ and CO₂, which helps to improve the biomass accumulation under the same substrate condition and provides certain strategic reference for the culture of chemoautotrophic bacteria.

[Objective] Rummeliibacillus, a genus encompassing three known species, R. stabekisii, R. pycnus, and R. suwonensis, has a wide range of potential applications in biodegradation, probiotics, animal feed, and production of arginine, caproic acid, and other compounds. This study aims to explore the genetic diversity of this genus at the genomic level. [Methods] A comparative pangenome analysis of 12 strains isolated from different sources was conducted. In addition, the phylogenetic analysis, functional annotation, genomic metabolic pathway analysis, and prediction of mobile genetic elements were carried out. [Results] A total of 8 024 gene clusters were identified. The core genome, accessory genome, and strain-specific genes comprised 1 550, 3 941, and 2 533 gene clusters, respectively. In the core genome, the arginine cycle of six strains was complete. Seven strains had the ability to completely biosynthesize acetoin. However, only R. pycnus and R. suwonensis 3B-1 were able to completely biosynthesize caproic acid. The phylogenetic tree, DNA-DNA hybridization, and average nucleotide identity showed that Rummeliibacillus sp. G93 and Rummeliibacillus sp. TYF-LIM-RU47 were strains of R. stabekisii. Rummeliibacillus sp. POC4 and Rummeliibacillus sp. TYF005 may belong to a new species of this genus. In addition, genomic islands were identified in all the 12 strains, with the number ranging from four (R. stabekisii DSM 25578 and R. stabekisii NBRC 104870) to 14 (Rummeliibacillus sp. SL167 and Rummeliibacillus sp. TYF005), and prophage sequences were found in five of the 12 strains. [Conclusion] This study provides a genomic framework for Rummeliibacillus that could assist the further exploration of this genus.

[Objective] To develop a rapid detector for biochemical oxygen demand (BOD) in the wastewater from ships entering ports in response to the stringent mandates of the International Maritime Organization (IMO). The objective is to facilitate swift detection of domestic wastewater produced by the multitude of vessels arriving at the port. [Methods] When testing the BOD standard solution, Clostridium butyricum and Bacillus subtilis were used to manufacture the biosensitive elements inducing electron transfer during the consumption of dissolved oxygen (DO), which led to a change in electrical conductivity (COND). By treating dissolved oxygen as a pivotal indicator and an intermediary in the monitoring process, this study explored the correlation between changes in electrical conductivity and sample concentration. Through the development of a quadratic polynomial fitting model that correlates electrical conductivity with dissolved oxygen levels, and by establishing a connection between dissolved oxygen and sample concentration, this research delves into the correlation between variations in electrical conductivity and the concentration of the sample. [Results] The changes in electrical conductivity exhibited by different solutions enabled the detector to rapidly distinguish between the wastewater with a BOD concentration higher than 25 mg/L (the slope of the COND variation value is less than -0.01) and that below 25 mg/L (the slope of the COND variation value is greater than -0.01). By establishing a highly correlated fitting curve between dissolved oxygen and electrical conductivity (coefficient of determination R²=0.977 83), this study achieved precise reading of samples within the ultra-low concentration range (BOD<25 mg/L). The accuracy rate of the measurements exceeded 85% in the in-suit tests conducted in Qinhuangdao, Hebei, China. [Conclusion] The measurement data read by the rapid detector for BOD is highly consistent with the results obtained by the dilution inoculation method. Moreover, the detector is capable of performing rapid quantitative analysis of BOD in domestic wastewater from ships entering ports within 30 min, demonstrating high detection efficiency.