Background: Biohydrogen production from lignocellulose has become an important hydrogen production method due to its diversity, renewability, and cheapness. Overexpression of the formate hydrogen lyase activator (fhlA) gene is a promising tactic for enhancement of hydrogen production in facultative anaerobicEnterobacter. As a species ofEnterobacter,Enterobacter cloacaewas reported as a highly efficient hydrogen-producing bacterium. However, little work has been reported in terms of cloning and expressing thefhlAgene inE. cloacaefor lignocellulose-based hydrogen production.Results: In this study, the formate hydrogen lyase activator (fhlA) gene was cloned and overexpressed inEnterobacter cloacaeWL1318. We found that the recombinant strain significantly enhanced cumulative hydrogen production by 188% following fermentation of cotton stalk hydrolysate for 24 h, and maintained improved production above 30% throughout the fermentation process compared to the wild strain. Accordingly, overexpression of thefhlAgene resulted in an enhanced hydrogen production potential (P) and maximum hydrogen production rate (R_m), as well as a shortened lag phase time (λ) for the recombinant strain. Additionally, the recombinant strain also displayed improved glucose (12%) and xylose (3.4%) consumption and hydrogen yield Y(H₂/S) (37.0%) compared to the wild strain. Moreover, the metabolites and specific enzyme profiles demonstrated that reduced flux in the competitive branch, including succinic, acetic, and lactic acids, and ethanol generation, coupled with increased flux in the pyruvate node and formate splitting branch, benefited hydrogen synthesis.Conclusions: The results conclusively prove that overexpression offhlAgene inE. cloacaeWL1318 can effectively enhance the hydrogen production from cotton stalk hydrolysate, and reduce the metabolic flux in the competitive branch. It is the first attempt to engineer thefhlAgene in the hydrogen-producing bacteriumE. cloacae. This work provides a highly efficient engineered bacterium for biohydrogen production from fermentation of lignocellulosic hydrolysate in the future.

Pear black spot disease seriously threatens the pear industry. Currently, its control mainly relies on chemical fungicides while biological control using antagonistic microorganisms represents a promising alternative approach. This study identified and characterized Bacillus velezensis TRMB57782 as a biocontrol strain through whole-genome sequencing. AntiSMASH analysis predicted the strain’s potential to produce secondary metabolites such as surfactin, difficidin, and bacilysin. In vitro experiments demonstrated that TRMB57782 inhibited the growth of Alternaria gaisen. In vivo experiments using excised branches and pear fruits at two different stages also showed significant control effects. A preliminary exploration of the metabolic substances of TRMB57782 was carried out. The strain can produce siderophores and three biocontrol enzymes. Crude extracts obtained by the hydrochloric acid precipitation and ammonium sulfate saturation precipitation of the bacterial liquid exhibited significant activity and volatile organic compounds showed biocontrol activity. Meanwhile, the effects of strain TRMB57782 on the hyphae of pathogenic fungi were studied, leading to hyphal atrophy and spore shrinkage. This paper provides an effective biocontrol strategy for fragrant pear black spot disease, reveals the antibacterial mechanism of Bacillus velezensis TRMB57782, and offers a new option for the green control of pear black spot disease.

Lop Nur, an extremely arid environment, harbors unique microbial resources and represents a potential reservoir for novel bioactive substances. With antibiotic resistance becoming an increasing global concern, the resistance traits of microorganisms in extreme habitats and their potential association with antibacterial activity remain poorly understood. This study aimed to investigate the diversity of soil microorganisms in Lop Nur, their resistance to norfloxacin, kanamycin, and amoxicillin, and their inhibitory activity against common pathogenic bacteria, thereby providing a scientific basis for the discovery of new antibacterial candidates. Surface soils from three sampling points in Lop Nur were inoculated onto Gao’s No.1 and LB media supplemented with different antibiotic regimens (single, pairwise, and triple combinations). Isolates were identified by 16S rRNA gene sequencing, their antibiotic resistance was assessed using the disk diffusion method, and antibacterial activity was evaluated using the agar well diffusion method. A total of 120 microorganisms were isolated, belonging to six phyla and nine genera, including 10 potential new species. The control group yielded the highest diversity (35 strains), whereas only 4 strains were recovered under triple-antibiotic treatment, demonstrating the strong selective effect of antibiotic stress. Resistance profiling showed that 88.14% of strains were resistant to amoxicillin, 64.71% to norfloxacin, and 60.68% to kanamycin, with multidrug resistance being widespread. Eleven strains exhibited antibacterial activity against five pathogens, including Staphylococcus aureus (maximum inhibition zone 53.51 mm), and nine of these strains also displayed antibiotic resistance, suggesting a potential association between resistance and antibacterial activity. Microorganisms isolated from Lop Nur displayed extensive resistance and notable antibacterial activity. Antibiotic stress strongly influenced the cultivable microbial isolates, facilitating the recovery of resistant strains with antibacterial potential. These findings provide a valuable reference for exploring microbial resources in extreme environments and highlight the potential link between antibiotic resistance and antibacterial activity.

As an agricultural planting practice, preceding cropping can not only enhance soil fertility and reduce pests and diseases but also boost crop yield and quality. In this study, SZS samples from different preceding cropping areas were selected as research subjects. Phenolic compounds were analyzed using high-performance liquid chromatography (HPLC), and antioxidant activities were assessed based on free radical scavenging effects. Variety differences were explored through chemical pattern recognition, and the spectrum-effect relationship between the fingerprint spectra of SZS and antioxidant activity was investigated using Pearson correlation analysis, grey relational analysis, and other methods. A total of 17 peaks were observed, among which 4 peaks were identified. They are gallic acid, catechin, spinosin, and scutellarin. The 22 SZS samples could be categorized into 3 groups, with cluster analysis and principal component analysis results being largely consistent. Spinosin, a marker compound of SZS, is a crucial contributor to the total antioxidant activity. In conclusion, the spectrum-effect relationship between phenolic compounds and the antioxidant activity of SZS was established, and the main characteristic components affecting antioxidant activity were identified, providing a reference for the quality evaluation of SZS and the development of its products.