Microbial Biotechnology最新文献

Rhizoctonia solani is a polyphagous necrotrophic fungal pathogen that causes sheath blight disease in rice. It deploys effector molecules as well as carbohydrate-active enzymes and enhances the production of reactive oxygen species for killing host tissues. Understanding R. solani ability to sustain growth under an oxidative-stress-enriched environment is important for developing disease control strategies. Here, we demonstrate that R. solani upregulates methionine biosynthetic genes, including Rs_MET13 during infection in rice, and double-stranded RNA-mediated silencing of these genes impairs the pathogen's ability to cause disease. Exogenous treatment with methionine restores the disease-causing ability of Rs_MET13-silenced R. solani and facilitates its growth on 10 mM H₂O₂-containing minimal-media. Notably, the Rs_MsrA gene that encodes methionine sulfoxide reductase A, an antioxidant enzyme involved in the repair of oxidative damage of methionine, is upregulated upon H₂O₂ treatment and also during infection in rice. Rs_MsrA-silenced R. solani is unable to cause disease, suggesting that it is important for the repair of oxidative damage in methionine during host colonization. We propose that spray-induced gene silencing of Rs_MsrA and designing of antagonistic molecules that block MsrA activity can be exploited as a drug target for effective control of sheath blight disease in rice.

Assisted reproductive techniques are routinely used in livestock species to increase and enhance productivity. Ovarian hyperstimulation is a process that currently relies on administering pituitary-derived follicle-stimulating hormone (FSH) or equine chorionic gonadotropin in combination with other hormones to promote the maturation of multiple follicles and thereby achieve superovulation. The use of partially purified preparations of FSH extracted from natural sources is associated with suboptimal and variable results. Recombinant FSH (rFSH) has been produced in a variety of heterologous organisms. However, attaining a bioactive rFSH of high quality and at low cost for use in livestock remains challenging. Here we report the production and characterization of a single chain bovine rFSH consisting of the β- and α-subunit fused by a polypeptide linker (scbFSH) using Leishmania tarentolae as heterologous expression system. This unicellular eukaryote is non-pathogenic to mammals, can be grown in bioreactors using simple and inexpensive semisynthetic media at 26°C and does not require CO₂ or bovine serum supplementation. Stable cell lines expressing scbFSH in an inducible fashion were generated and characterized for their productivity. Different culture conditions and purification procedures were evaluated, and the recombinant product was biochemically and biologically characterized, including bioassays in an animal model. The results demonstrate that L. tarentolae is a suitable host for producing a homogeneous, glycosylated and biologically active form of scbFSH with a reasonable yield.

Developing protein-based vaccines against bacteria has proved much more challenging than producing similar immunisations against viruses. Currently, anti-bacterial vaccines are designed using methods based on reverse vaccinology. These identify broadly conserved, immunogenic proteins using a combination of genomic and high-throughput laboratory data. While this approach has successfully generated multiple rationally designed formulations that show promising immunogenicity in animal models, few have been licensed. The difficulty of inducing protective immunity in humans with such vaccines mirrors the ability of many bacteria to recolonise individuals despite recognition by natural polyvalent antibody repertoires. As bacteria express too many antigens to evade all adaptive immune responses through mutation, they must instead inhibit the efficacy of such host defences through expressing surface structures that interface with the immune system. Therefore, ‘immune interface interference’ (I3) vaccines that target these features should synergistically directly target bacteria and prevent them from inhibiting responses to other surface antigens. This approach may help us understand the efficacy of the two recently introduced immunisations against serotype B meningococci, which both target the Factor H-binding protein (fHbp) that inhibits complement deposition on the bacterial surface. Therefore, I3 vaccine designs may help overcome the current challenges of developing protein-based vaccines to prevent bacterial infections.

Global plastic waste accumulation has become omnipresent in public discourse and the focus of scientific research. Ranking as the sixth most produced polymer globally, polyurethanes (PU) significantly contribute to plastic waste and environmental pollution due to the toxicity of their building blocks, such as diisocyanates. In this study, the effects of PU on soil microbial communities over 18 months were monitored revealing that it had marginal effects on microbial diversity. However, Streptomyces sp. PU10, isolated from this PU-contaminated soil, proved exceptional in the degradation of a soluble polyester-PU (Impranil) across a range of temperatures with over 96% degradation of 10 g/L in 48 h. Proteins involved in PU degradation and metabolic changes occurring in this strain with Impranil as the sole carbon source were further investigated employing quantitative proteomics. The proposed degradation mechanism implicated the action of three enzymes: a polyester-degrading esterase, a urethane bond-degrading amidase and an oxidoreductase. Furthermore, proteome data revealed that PU degradation intermediates were incorporated into Streptomyces sp. PU10 metabolism via the fatty acid degradation pathway and subsequently channelled to polyketide biosynthesis. Most notably, the production of the tri-pyrrole undecylprodigiosin was confirmed paving the way for establishing PU upcycling strategies to bioactive metabolites using Streptomyces strains.

It is with profound sadness that we announce the passing of Pierre Cornelis on 2 December 2023. Born in Kinshasa, Democratic Republic of Congo, on 4 November 1949, Pierre Cornelis left an indelible mark on the scientific community through his remarkable academic achievements and groundbreaking research in microbiology, especially on Pseudomonas.

Pierre commenced his academic journey by completing a doctoral thesis on isoaccepting tRNA species from healthy and crown gall tobacco tissues at the Catholic University of Louvain (Belgium). His pursuit of knowledge led him to a postdoctoral stay at the Weizmann Institute of Science in Rehovot, Israel. His interest in bacterial iron homeostasis began in 1985 during his tenure at the Institute of Cellular Pathology (ICP-UCL) in Brussels. Subsequently, he spent the majority of his career at the Vrije Universiteit Brussel. As a professor at Vrije Universiteit Brussel, Pierre shared his extensive knowledge with students in microbiology and biology, leaving a positive impact on the education of numerous generations. In recognition of his outstanding contributions, Dr. Pierre was honoured as Prof. Emeritus in October 2014.

P. Cornelis dedicated his scientific career to Pseudomonas, with a particular focus on the iron uptake pathways of these bacteria, the molecular mechanisms involved in the killing of Pseudomonas cells by pyocins, cell–cell communication in Pseudomonas, and gene regulation by environmental signals.

P. Cornelis' research provided comprehensive insights into the diversity, evolution and functionality of siderophores and their corresponding outer membrane transporters in various Pseudomonas species, contributing to the understanding of iron acquisition mechanisms and their implications in microbial competition and pathogenicity. Indeed, iron is a key nutrient for bacteria, paradoxically poorly bioavailable because it is poorly soluble under aerobic conditions. To access iron, most bacteria produce siderophores, small molecules with a very high affinity for iron (Hider & Kong, 2011). After scavenging iron in the bacterial environment, the ferrisiderophore complexes are recognized and imported across the outer membrane by TonB-dependent outer membrane transporters (TBDTs) in Gram-negative bacteria (Schalk et al., 2012). Pyoverdines are a family of siderophores produced by fluorescent Pseudomonads, giving a typical yellow-green colour to Pseudomonas cultures (Ravel & Cornelis, 2003). These siderophores have peptide chains that are quite diverse, and more than 50 pyoverdine structures have been elucidated.

With his research team and colleagues, Pierre identified and contributed to the structure determination of new pyoverdines, such as the ones produced by Pseudomonas entomophila or Pseudomonas putida W15Oct28 (Budzikiewicz et al., 2007; Matthijs et al.,