Lignin, the most abundant aromatic biopolymer resource in the nature, is difficult to be degraded by common microorganisms due to its complexity and highly aggregated aromatic structure. Lignin-degrading microorganisms from extreme environments are considered as suitable candidates for lignin bioprocessing. This review summarizes several types of extremophiles capable of degrading lignin and the extremozymes produced by them and elucidates the properties, catalytic mechanisms, and metabolic pathways of the extremozymes. Furthermore, this article discusses the prospects for the identification of novel extremophiles and extremozymes by multi-omics and makes an outlook on the development and utilization methods of extremophiles, with a view to providing a reference for the subsequent screening and development of more efficient lignin-degrading strains.

Chitin is a polysaccharide that is polymerized by N-acetylglucosamine through β-1, 4 glycosidic linkages and ubiquitous in the global terrestrial and aquatic ecosystems. Chitin is one of the most abundant organic macromolecular polymers on earth. Chitinases are a class of enzymes that catalyze the degradation of chitin. Chitinases are not only the focus of basic research but also have shown broad application potential in a variety of fields such as agriculture, medicine, and environmental science. This paper systematically reviewed the research progress in fungal chitinases in terms of the classification, distribution characteristics in different fungal taxa, biological functions in yeasts and filamentous fungi, enzymatic characteristics, and applications in agricultural pest and disease control, disease treatment, and production of chitooligosaccharides. Furthermore, we discussed the future research directions of fungal chitinases. This paper provides new perspectives for the study of fungal chitinases.

Porcine deltacoronavirus (PDCoV), an emerging virus globally prevalent, causes watery diarrhea, vomiting, and dehydration of newborn piglets, posing severe economic losses in the swine industry. Moreover, with the characteristic of cross-species transmission, PDCoV can infect human and farmed animals, posing a serious threat to human health. Pyroptosis is a form of programmed cell death mediated by members of the Gasdermin family, which plays a role in defending and eliminating viruses. Coronaviruses, however, have developed precise strategies to antagonize pyroptosis and evade immune responses. This review expounds the biological characteristics of PDCoV, the process of pyroptosis, and the antagonism of Gasdermin D-mediated pyroptosis by PDCoV, aiming to enrich the knowledge about the antagonism of immune responses by PDCoV and lay a theoretical foundation for the prevention and control of this virus.

[Objective] To study the effects of endoplasmic reticulum stress on the regulation of the lifespan and autophagy of Saccharomyces cerevisiae by the protein O-mannosyltransferase 1 (PMT1). [Methods] The double deletion strain (pho8Δ60 pmt1Δ) was constructed based on the genetic homologous recombination. The daughter cells produced by the mother cell of the PMT1-deleted yeast strain (pmt1Δ) treated with tunicamycin (inducing endoplasmic reticulum stress) were counted under a light microscope, and the replicative lifespan of the strain was examined. A microplate reader was used to measure the alkaline phosphatase activity of the pho8Δ60 pmt1Δ strain in the SD-N medium (for inducing autophagy). Western blotting was employed to determine the expression level of the autophagy marker Atg8 in the presence of tunicamycin. The transcript levels of autophagy-related genes ATG1 and ATG8 in the pmt1Δ strain treated with tunicamycin were determined by RT-qPCR. [Results] The replicative lifespan of the pmt1Δ strain was shortened by 38.7%, while the alkaline phosphatase activity of pmt1Δ strain was increased compared with those of the wild type in the presence of tunicamycin. The expression levels of GFP-Atg8 fusion protein and free GFP in the pmt1Δ strain were up-regulated with the increase in the concentration of tunicamycin. The transcript levels of ATG1 and ATG8 were up-regulated in the pmt1Δ strain treated with tunicamycin. [Conclusion] Endoplasmic reticulum stress impairs the replicative lifespan and enhances the autophagy of PMT1-deleted yeast cells.

[Objective] To study the transcriptome regulation mechanism of Fusarium graminearum under different pH stress conditions, analyze the changes in gene expression levels, explore the metabolic pathways involved in the responses of F. graminearum cells to acidic or alkaline conditions, and reveal how F. graminearum regulates intracellular metabolism and synthesis to adapt to the changes in extracellular pH. [Methods] F. graminearum was cultured in the PDB media with initial pH 4.5, 6.5, and 8.0 for 48 h, and the total RNA of the strains was extracted to construct the cDNA library. Transcriptome sequencing and bioinformatics analysis were used to identify the differentially expressed genes (DEGs), and the metabolic pathways involved were analyzed. The expression levels of target genes were determined by RT-qPCR. [Results] Under acidic conditions, a total of 4 283 DEGs were identified, including 2 032 genes with up-regulated expression and 2 251 genes with down-regulated expression. Under alkaline conditions, a total of 498 DEGs were identified, including 269 genes with up-regulated expression and 229 genes with down-regulated expression. Gene ontology (GO) enrichment analysis revealed 211 GO terms for the up-regulated genes and 72 GO terms for the down-regulated genes under acidic conditions. Under alkaline conditions, GO analysis yielded 33 GO terms for the up-regulated genes and 40 GO terms for the down-regulated genes. The results of Kyoto encyclopedia of genes and genomes (KEGG) enrichment analysis showed 22 up-regulated pathways and 32 down-regulated pathways under acidic conditions as well as 8 up-regulated pathways and 13 down-regulated pathways under alkaline conditions. The expression of the genes associated with membrane transporters and hydrolysis of carbohydrates was up-regulated, and that of the genes related to protein metabolism was down-regulated, which assisted F. graminearum cells to adapt to changes in the external environment. At the same time, F. graminearum maintained the internal environment balance by reducing secondary metabolism and amino acid metabolism under acidic and alkaline conditions, respectively, to resist extracellular pH stress. [Conclusion] In the acidic environment, F. graminearum adapts to the changes in the extracellular environment by promoting the production of ribonucleoprotein complexes and secondary metabolism. In an alkaline environment, F. graminearum senses and responds to external stresses via amino acid metabolism. The analysis of the metabolic pathways of F. graminearum cells provides gene expression data for studying the responses of F. graminearum to different pH environments. The findings of this study are helpful to understand the pathogenic mechanism of F. graminearum.

[Objective] Riemerella anatipestifer (RA) is a Gram-negative bacterium that mainly infects domesticated birds such as ducks and geese. The clinical isolates of RA are multi-drug resistant and increasing year by year. However, the transmission ways of antibiotic resistance genes in RA have not been identified. This study aims to identify the transmission ways and distribution of antibiotic resistance genes in the clinical isolates of RA. [Methods] The drug resistance phenotypes of the reference strain RA ATCC 11845 and the clinical isolates RA CH-1 and RA CH-2 to 28 antibiotics belonging to 10 categories were determined. The antibiotic resistance genes were identified by genome analysis and construction of gene deletion strains. The transmission ways of antibiotic resistance genes were identified by natural transformation. The distribution of these resistance genes in different clinical isolates was detected by PCR. [Results] RA CH-1 and RA CH-2 were resistant to β-lactams, tetracyclines, macrolides, lincosamides, and amide alcohols, while RA ATCC 11845 was sensitive to the above antibiotics. The resistant strains became sensitive to the corresponding antibiotics after the deletion of 13 resistance genes, respectively, indicating that these genes were involved in antibiotic resistance. All the resistant genes can be transferred to the sensitive strain RA ATCC 11845 by natural transformation. The detection rates of resistance genes in 100 clinical isolates from 2017 to 2023 varied within the range of 3% to 89%. [Conclusion] Antibiotic resistance genes can be transmitted in RA through natural transformation, and different antibiotic resistance genes presented varied distribution in clinical isolates, among which tetX (B739_0030) and bla_OXA (G148_1768) were carried by the most and fewest strains, respectively.

Probiotics refer to live microorganisms that are beneficial to the health of the host when ingested in sufficient quantities, and their beneficial effects have been widely recognized. However, the probiotic function of probiotics is strain-specific. As more and more emerging technologies are introduced into the research on probiotics, the screening of probiotics with specific functions according to individual needs has become a research hotspot. Conventional probiotic screening methods have limitations and cannot meet the current demand for precision medicine. Therefore, a bottom-up precision screening strategy for probiotics based on phenotyping, genotyping, and target is of great practical significance. This article discusses the theoretical basis, methods, and technologies of accurate screening of probiotics from phenotype, genotyping, and target, and the application and safety evaluation of probiotics, aiming to provide reference for the accurate screening of probiotics.

[Objective] To study the species and community structure of bacteria in winged and wingless Megoura crassicauda (Mordvilko). [Methods] Illumina MiSeq high-throughput sequencing was carried out for the V3−V4 variable region of bacterial 16S rRNA gene. [Results] A total of 4 746 449 sequences were obtained and annotated to 586 operational taxonomic units (OTUs) belonging to 477 species, 336 genera, 192 families, 106 orders, 46 classes of 25 phyla. Firmicutes, Actinobacteria, Proteobacteria, and Cyanobacteria were the dominant phyla in all samples. The dominant genera included Staphylococcus, Corynebacterium, and Buchnera. At the phylum level, the relative abundance of Proteobacteria, Cyanobacteria, and Deinococcus-Thermus in the winged morph was significantly higher than that in the wingless morph. At the genus level, the relative abundance of Buchnera, Exiguobacterium, Pseudomonas, Glutamicibacter, and Pseudonocardia in the winged morph was significantly higher than that in the wingless morph. [Conclusion] This study clarified the diversity and community structure of the bacteria in winged and wingless M. crassicauda and provided a reference for exploring the role of bacteria in the wing differentiation of aphids and developing new methods for pest control.

With the increasing emphasis on health, probiotics have garnered increasing attention due to their safe and beneficial features for intestinal health and have become a hot spot in the fields of food and medicine. In terms of oral drug delivery, it is difficult to select a safe, convenient, and stable carrier. Probiotics can be used as carriers to deliver drugs through the complex in vivo environment without damage and have excellent safety and stability. This review describes the structures, advantages, and disadvantages of five common probiotic-based oral drug delivery approaches: display on spore surface, yeast microcapsules, recombinant probiotic expression, bacterium-like particles, and bacterial ghost, aiming to provide options for the application of oral delivery carriers.

Giant pandas, despite having the digestive systems of carnivores, have evolved to thrive on a bamboo-based vegetarian diet, which results in a unique gut microbiota. With the advancement of science and technology, our understanding of the gut microbiota of giant pandas has evolved from simple strain isolation to exploring the intricate relationship between the microbiota and metabolic functions of the hosts as well as predicting the functions of the microbiota. In this review, we summarize the characteristics of the bacterial and fungal communities in giant pandas, examining the effects of the factors such as age, diet, habitat, and health conditions on gut microbiota. Furthermore, we discuss how these factors influence the metabolism of the gut microbiota. This review is expected to provide a theoretical basis for the future research on the intricate structure and functions of gut microbiota in giant pandas. The knowledge can pave the way for innovating the measures to enhance and stabilize the gut microecological environment, ultimately contributing to the conservation of giant pandas.