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A facultative exoelectrogen, Cellulomonas fimi strain Clb-11, was isolated from polluted river water. This strain could generate electricity in microbial fuel cells (MFCs) with carboxymethyl cellulose (CMC) as the carbon source, and the maximum output power density was 12.17 ± 2.74 mW·m−2. In addition, Clb-11 could secrete extracellular chromate reductase or extracellular electron mediator to reduce Cr(VI) to Cr(III). When the Cr(VI) concentration was less than 0.5 mM in Luria-Bertani (LB) medium, Cr(VI) could be completely reduced by Clb-11. However, the Clb-11 cells swelled significantly in the presence of Cr(VI). We employed transcriptome sequencing analysis to identify genes involved in different Cr(VI) stress responses in Clb-11. The results indicate that 99 genes were continuously upregulated while 78 genes were continuously downregulated as the Cr(VI) concentration increased in the growth medium. These genes were mostly associated with DNA replication and repair, biosynthesis of secondary metabolites, ABC transporters, amino sugar and nucleotide sugar metabolism, and carbon metabolism. The swelling of Clb-11 cells might have been related to the upregulation of the genes atoB, INO1, dhaM, dhal, dhak, and bccA, which encode acetyl-CoA C-acetyltransferase, myo-inositol-1-phosphate synthase, phosphoenolpyruvate-glycerone phosphotransferase, and acetyl-CoA/propionyl-CoA carboxylase, respectively. Interestingly, the genes cydA and cydB related to electron transport were continuously downregulated as the Cr(VI) concentration increased. Our results provide clues to the molecular mechanism of Cr(VI) reduction by microorganisms in MFCs systems.

Highly flexible loop regions can affect the structure-function relationship of enzymes. In this study, to reveal the effect of the loop on the thermal stability of GH11 xylanase XynASP from Aspergillus saccharolyticus JOP 1030-1, three mutants (T41V, A79Y, T81Q) located in the loop region were predicted by the FireProt web server and constructed by site-directed mutagenesis. Heat tolerance experiments were performed in the mutants and wild-type XynASP, as well as for previously reported mutant T41W, indicating that the thermostability of enzymes from weak to strong was wild-type XynASP, T41V, T81Q, A79Y and T41W. Novel hydrophobic contacts and hydrogen bonds in the single mutants were found and explained for enhanced thermostability. T41W, A79Y and T81Q were combined by site-directed mutagenesis. The combined double mutants T41W/A79Y and A79Y/T81Q displayed significantly higher thermostability than that of the wild-type, yet lower than that of the robust mutant T41W after 30 min of incubation at 35–60 °C. But the triple mutant T41W/A79Y/T81Q displayed a slight improvement in thermal stability compared to T41W after 30 min of incubation at 35–60 °C. Meanwhile, T41W/A79Y/T81Q exhibited substantially improved thermostability with a half-life of inactivation enhanced from 20.7 min to 127.0 min at 45 °C. Furthermore, the optimum temperature increased by 10 °C compared to the wild-type XynASP. The pH stability of T41W/A79Y/T81Q at pH 3.0-8.0 all obtained more than 88% residual activities, displaying a significant improvement compared to the wild-type XynASP (40–70% residual activities) at the same conditions. This study confirms that designing GH11xylanases in the loop region is an effective strategy for obtaining thermostabilizing xylanases.

Oxidative stress is one of the main causes of testicular spermatogenesis disorders. Resveratrol (RES) can inhibit oxidative stress levels, reduce germ cell damage, and promote spermatogenesis. To investigate the molecular mechanism by which RES promotes spermatogenesis, the effects of hydrogen peroxide (H2O2) on the pathological damage of mouse testis tissue were assessed. The expression of key genes associated with pyroptosis, apoptosis, and autophagy, and the effects of RES on this process were determined. Experimental mice were divided into three groups with intraperitoneally injection of H2O2 (3 mmol/kg/d), RES (100 mg/kg/d) + H2O2 (3 mmol/kg/d), and normal saline, respectively. The testicular tissues were collected, and the pathological changes were observed by hematoxylin and eosin staining. The ultrastructure was observed using transmission electron microscopy (TEM). The transcriptional levels of pyroptosis, apoptosis, and autophagy-related genes were measured and analyzed by fluorescence quantitative polymerase chain reaction. The results showed that, in the H2O2 group, the basal membrane of spermatogenic tubules was damaged, atrophic, and thin. Interstitial cells were fragmented, and the gap of spermatogenic tubules increased. Compared with the H2O2 group, the pathological damage of testicular tissue structure in the H2O2 + RES group was significantly ameliorated. TEM results showed no evident damage to the cell structure in the control group, while apoptosis, autophagy, and pyroptosis were observed in the testicular tissue of H2O2 and H2O2 + RES groups, where cell damage was less, but apoptotic bodies, autophagosomes, and pyroptosomes were observed. The transcription levels of key pyroptosis genes increased in the H2O2 group but decreased significantly after RES treatment. The results indicated that H2O2 could induce pyroptosis, while RES inhibited pyroptosis and led to the release of inflammatory factors by regulating the expression of genes in signaling pathways. After H2O2 injection, the transcript levels of key apoptosis genes in testicular tissue were lower than those in the control group, while RES promoted the occurrence of H2O2-induced apoptosis, to achieve the purpose of protecting itself from oxidative damage. H2O2 could promote autophagy in mouse testicular tissue. RES enhanced the level of H2O2-induced autophagy, removed the damaged cells in the testicular tissue, and protected the development of the body. This study provided the experimental basis for the study of RES in oxidative damage, pyroptosis, apoptosis, and autophagy, and theoretical guidance and new ideas for drug development and treatment of male reproductive diseases in clinical practice. [ABSTRACT FROM AUTHOR]

Tobacco smoke is the leading risk factor for lung cancer, accounting for over 80% of lung cancer deaths. Reducing the damage of cigarette smoke to the lungs through dietary therapy is currently a research hotspot. It has been reported that cigarette smoke extract induced inflammation and contributed to pyroptosis through the ROS/NLRP3/caspase-1 pathway in human bronchial epithelial cells. To investigate the effect of ginger and snow pear beverage on smoke-induced pyroptosis, ginger, snow pear, loquat, honey, and skimmed milk powder were used to prepare a lung moistening drink with excellent palatability. Male rats were divided into the drink group and control group and exposed to cigarette smoke for 60 days. Blood biochemical indices and organ coefficients were measured, and lung and small intestine tissues were excised for HE staining. The mRNA expression of pyroptosis in the lung tissue was evaluated by fluorescence quantitative polymerase chain reaction (qPCR). The results showed that globulin and urea nitrogen levels were significantly higher in control (C) group than that in beverage (B) group, while the opposite effect was observed for the albumin/globulin ratio and cholesterol level. The changes in the weight of the lung tissue were obvious and significantly higher in group B than that in group C. The histological structure of the lung tissue in group C was abnormal with evidence of significant pathological changes in the alveolar wall and capillary bronchial tube wall along with a few inflammatory cells. The pathological changes in group B showed significantly improved. The small intestinal villus length, intestinal crypt depth, goblet cell number, and V/C value were significantly higher in group B. In addition, the drink significantly reduced the mRNA expression of NLRP3, caspase1, GSDMD, IL-18, and IL-1β genes in the lung tissue. The results indicated that the tested drink exerted protective effects on the lungs and small intestine, which inhibited the release of inflammatory factors from the cellular pyroptosis signaling pathway, alleviated the occurrence of pyroptosis, protected the lung tissue, and reduced the cigarette smoke-induced damage and lesions. [ABSTRACT FROM AUTHOR]

Organic fertilizers have been shown to positively impact soil microorganisms and the physical and chemical properties of soil. This study utilized high-throughput sequencing technology to analyze the composition and structure of the soil microbial community after organic fertilizer application. Enzyme activity, water content, and organic matter were also measured. The findings indicated that organic fertilizer application resulted in lower soil pH and reduced rates of miscellaneous bacteria, while increasing enzyme activity, water content, and organic matter. Moreover, the use of organic fertilizers improved alpha and beta diversity of soil microorganisms with Firmicutes experiencing a significant increase at the phylum level, and Bacillus, SBR1031, and Sphingomonas exhibiting higher relative abundance at the genus level. Conversely, levels of soil microorganisms like Nocardioides, Solidubrobacter, and Microvirga were lower in the organic fertilizer group compared to the control group. The application of PICRUST2 revealed significant up-regulation of PWY-6174 (mevalonate pathway II (haloarchaea)), ASPASN-PWY (super pathway of L-aspartate and L-asparagine biosynthesis), and PWY0-42 (2-methylcitrate cycle I) pathways in the organic fertilizer group, demonstrating the positive impact of organic fertilizers on microbial communities. Further analysis of the species composition of these pathways showed that in PWY-6174 pathway, Marine_ Group_ II in the control group displayed higher relative abundance than that in the organic fertilizer group (P < 0.05). In PWY0-42 pathways, the relative abundance of Rhodanobacter, Chujaibacter, Dyella, Luteimonas, and Thermomonas in organic fertilizer group was significantly higher than that in control group (P < 0.05). In ASPASN-PWY pathway, the relative abundance of Bacillus, Fonticella, Romboutsia, Chloroplast, and Tepidimicrobium in organic fertilizer group was significantly higher than that in control group (P < 0.05). In conclusion, this study indicated that organic fertilizers could effectively enhance the structure and composition of the soil microbial community, leading to improvements in the physical and chemical properties of soil. [ABSTRACT FROM AUTHOR]

Xylanases which hydrolyze ß-1,4-glycosidic bonds of xylans to yield xylooligosaccharides have a potential to be used in pulp bleaching, food processing, and feed processing. However, the poor thermostability of xylanases is a critical limiting factor in industrial applications. The thermostability of xylanases can be improved by protein engineering and computer-assisted design. In the present study, the thermostabilizing mutation G143W locating at the cord region of xylanase XynXM from Aspergillus brunneoviolaceus CBS 621.78 was predicted by the FireProt web server and constructed by site-directed mutagenesis. Heat tolerance experiments were performed in mutant G143W and wildtype XynXM. G143W exhibited a substantially improved thermostability with half-life of inactivation at 45°C enhanced from 41.5 min to 65.3 min, which was approximately 1.6-fold increase over that of wildtype. Furthermore, the optimum temperature was 50°C, which has the best reactive activity, and 5°C higher than that of XynXM (45°C). The reactive optimal pH of G143W increased from pH 5.0 to pH7.0. The pH stability span (4.0-9.0) of G143W displayed a significant improvement comparing to that of XynXM. Comparing to the wildtype, the half-life of G143W at 35°C in simulated intestinal fluid (pH 6.8, 10 mg/mL trypsin solution) was increased by 35.8 min. Novel hydrophobic contacts and hydrogen bonds were discovered in the model of G143W, which explained the reason of enhanced thermal stability. The key residues Trp57, Asn84, Val86, Tyr114, Gln117, Trp120, Glu127, Tyr137, Pro139, Ser141, Thr144, Ala161, Pro167, and Glu218 were identified in protein-ligand interaction by the molecular docking analysis using AutoDock Vina, which contributed to the catalytic activity and stability of enzyme. This study developed a thermostabilizing mutant G143W locating in the cord region of xylanase by the prediction of FireProt web server, which laid a foundation for exploring the functional relationship between cord region and xylanase XynXM. [ABSTRACT FROM AUTHOR]

Poor thermal stability is the main limiting factor for the industrial application of xylanase. To explore the way to improve the thermal stability of xylanase and obtain thermostable xylanase, a mesophilic xylanase gene (xynASP) (GenBank accession number: XM_025579666.1) derived from Aspergillus saccharolyticus JOP 1030-1 was mined by using the BLAST program and Thermomonospora fusca xylanase gene (TfxA) (GenBank accession number: KF927166.1) as the probe. The mined gene without signal peptide was cloned into Escherichia coli BL21 (DE3) cells by using the pET-28a expression system. Enzymatic characterization and conformation analysis showed that the recombinant XynASP belonged to GH11 family mesophilic xylanase with poor heat resistance, which limits the industrial applications of the enzyme at high temperature conditions. To rapidly enhance thermostability, the aromatic amino acids tryptophan was introduced at the 41st site of N-terminal of recombinant XynASP to design the variant T41W. The results experimentally confirmed that the beneficial variant T41W displayed the optimum temperature increased by 10°C comparing to that of the wild type XynASP. The half-life of inactivation of the variant T41W increased to 127.7 min at 45°C, which was approximately 6.2-fold longer than that of the wild type and exhibited a substantially improved thermostability. In addition, the variant T41W exhibited a high stability after incubated with metal ions and different concentrations of various organic solvents (methanol, ethanol, and isopropanol), which was similar to that of the wild type XynASP. This study demonstrated that the enzyme could be rapidly designed and substantially improved thermostability by site-directed mutagenesis. The resulted variant T41W could be a prospective candidate for industrial application. [ABSTRACT FROM AUTHOR]

Hydrogen sulfide is a colorless, highly toxic, water-soluble acidic gas. When the concentration in a chicken house exceeds the tolerance range of chicken, hydrogen sulfide will stimulate their mucosa and damage their sense of smell. It can also reduce the chicken’s appetite, growth performance, and resistance to disease. This study was aimed to separate desulfurizing bacterial strains from fresh chicken manure to reduce the impact of hydrogen sulfide on chickens, humans, and environmental pollution more generally. With the methods of enrichment culture, plate separation, and barium chloride screening, four desulfurizing bacterial strains (L1, L2, L3, and L4) were isolated from chicken manure. They were identified as Providencia sp., Arthrobacter AMP-5, Arthrobacter AMP-6, and Thiobacillus sp. by 16S rRNA sequencing. The desulfurization effects of these bacteria were investigated. The results showed that the desulfurization rate of Thiobacillus sp. reached 35.3%, which is the highest among the four strains and suggested that Thiobacillus sp. might be an effective sulfur bacterium degrading hydrogen sulfide. [ABSTRACT FROM AUTHOR]