Microbial Biotechnology最新文献

Bacteria and fungi produce a wide range of specialised metabolites, including volatile organic compounds (VOCs) that can act as signals or act directly to inhibit niche-competing microbes. Despite their ecological importance, most VOCs involved as signalling compounds remain uncharacterised. We have previously screened a collection of Actinobacteria strains sourced from Western Australia for their ability in vitro to suppress the growth of plant fungal pathogens. Here we explored the potential of four of the most active strains to produce antifungal metabolites by growing the strains on a range of nutrient-containing media. A casein-based (CYPS) culture medium was found to induce the production of antifungal compounds with high activity against Sclerotinia sclerotiorum, a major necrotrophic fungal pathogen of crops such as canola. We further observed that VOCs were produced that influenced pH and affected the bacterium-fungus interaction. The presence of Sclerotinia induced further VOC production in the Actinobacteria. Solid-phase microextraction (SPME) coupled with gas chromatography–mass spectrometry (GC–MS) analysis identified 2,4,6-trimethylpyridine, a compound not identified previously from Actinobacteria, which showed antifungal activity against different isolates of S. sclerotiorum and increased the pH of the medium. Overall, this study showed that Actinobacteria or their volatile products have the potential to be used in the protection of crops against S. sclerotiorum.

West Nile virus (WNV) disease, a mosquito-transmitted Flavivirus infection, represents a substantial public health research interest. This virus was unknown in the Western hemisphere until it was introduced in 1999 into an immunologically naïve population. WNV caused an epizootic and epidemic in New York City. The infection then swept over North America, causing mass mortality in birds and cumulatively 60,000 human cases, half of whom were hospitalised, mostly with neurological symptoms. The virus closely resembled a goose virus isolated in Israel in 1998. Mosquitoes of the genus Culex were identified as the insect viral vectors. WNV can infect more than 300 bird species, but in the US, the American robin (Turdus migratorius) represented the ecologically most important bird viral reservoir. Mosquito-to-mosquito viral transmission might amplify the viral spread, and iatrogenic WNV transmission was also observed, leading to the screening of blood products. Compared with African WNV isolates, the New York WNV isolate NY99 showed a mutation in the nonstructural protein NS3 that increased its virulence in birds and was also observed in WNV outbreaks from Romania in 1996 and from Russia in 1999. During its spread across the US, NY99 acquired a mutation in the envelope gene E that favoured viral infection in the insect vector. Europe reported 1200 annual WNV cases in 2024, with a focus in Mediterranean countries, but a northward spread of the infection to Germany and The Netherlands was also noted. Global warming is likely to affect the geographical distribution of vector-borne infections such that people living in temperate climate areas might be increasingly exposed to these infections. Therefore, research on temperature effects on WNV transmission by Culex mosquitoes has become a recent focus of research. Pertinent climate aspects of WNV infections are retraced in the present review.

Antimicrobial resistance (AMR) poses a global threat to human, animal and environmental health. Among the multidisciplinary tasks aimed at collectively tackling the AMR crisis, surveillance, research and education stand as major priorities. Based on a crowdsourcing research strategy, the MicroMundo project, a partner of the Tiny Earth initiative in Spain and Portugal, has been developed and consolidated with success in the academic environment. The objectives are focused on promoting research and, especially, on bringing knowledge of One Health and microbiology concepts, as well as AMR awareness to the community. Following a service-learning approach, MicroMundo integrates university and secondary/high school students in a citizen science-based research project to collectively isolate microorganisms with the potential to produce new antibiotics from soil environments. Over the last 7 years, 32 MicroMundo hubs operating across 31 different Portuguese and Spanish universities have recruited thousands of teenagers in this quest. Here we review the outcome of this unprecedented effort from a scientific and an educational perspective.

Bacteria and fungi produce a wide range of specialised metabolites, including volatile organic compounds (VOCs) that can act as signals or act directly to inhibit niche-competing microbes. Despite their ecological importance, most VOCs involved as signalling compounds remain uncharacterised. We have previously screened a collection of Actinobacteria strains sourced from Western Australia for their ability in vitro to suppress the growth of plant fungal pathogens. Here we explored the potential of four of the most active strains to produce antifungal metabolites by growing the strains on a range of nutrient-containing media. A casein-based (CYPS) culture medium was found to induce the production of antifungal compounds with high activity against Sclerotinia sclerotiorum, a major necrotrophic fungal pathogen of crops such as canola. We further observed that VOCs were produced that influenced pH and affected the bacterium-fungus interaction. The presence of Sclerotinia induced further VOC production in the Actinobacteria. Solid-phase microextraction (SPME) coupled with gas chromatography–mass spectrometry (GC–MS) analysis identified 2,4,6-trimethylpyridine, a compound not identified previously from Actinobacteria, which showed antifungal activity against different isolates of S. sclerotiorum and increased the pH of the medium. Overall, this study showed that Actinobacteria or their volatile products have the potential to be used in the protection of crops against S. sclerotiorum.

Natural products comprise a wide diversity of compounds with a range of biological activities, including antibiotics, anti-inflammatory and anti-tumoral molecules. However, we can only access a small portion of these compounds due to various technical difficulties. We have herein developed a novel and efficient approach for accessing biosynthetic gene clusters (BGCs) that encode natural products from soil bacteria. The pipeline uses a combination of long-read sequencing, antiSMASH for BGC identification and Transformation-associated recombination (TAR) for cloning the BGCs. We hypothesized that a genome assembly using Oxford Nanopore Technology (ONT) sequencing could facilitate the detection of large BGCs at a relatively fast and low-cost DNA sequencing. Despite the relative low accuracy and sequence mistakes due to high GC content and sequence repetitions frequently found in BGC containing bacteria, we demonstrate that ONT long-read sequencing and antiSMASH are effective for identifying novel BGCs and enabling TAR cloning to isolate the BGC in a desired vector. We applied this pipeline on a previously non-sequenced myxobacteria Aetherobacter fasciculatus SBSr002. Our approach enabled us to clone a previously unknown BGC into a genome engineering-ready vector, illustrating the capabilities of this powerful and cost-effective strategy.

Science communicators are more critical than ever in a time when misinformation and hoaxes dominate social media, especially during global emergencies like the COVID-19 outbreak. Researchers are good at communicating with peers but often struggle to explain complex ideas to the public. As shown previously, expanding outreach by combining science and art is not only possible, but effective. In the case of microbiology, the synergy between these two apparently divorced areas can help educating our communities and raising microbiological awareness, especially among students. Since Alexander Fleming's pioneering attempts, microorganisms have fascinated artists. Art may help us demystifying microbes and making them more approachable, improving public involvement with science. This article presents two personal experiences using art to teach and communicate scientific ideas (mainly from the microbiology field) to our fellow citizens. Above all, we emphasise the importance of contributing to the scientific literacy of our societies at all ages—including underrepresented and disadvantaged groups—by exploring novel ways to address this gap. By doing so, we align with the concepts and aims of the International Microbiology Literacy Initiative (IMiLI).

Daptomycin (DAP) is a cyclic lipopeptide antibiotic produced by Streptomyces roseosporus, and its biosynthesis is precisely regulated by a complex regulatory network. Although the biosynthetic pathway of DAP has been elucidated, the regulatory mechanism governing its biosynthesis at the transcriptional level is not yet fully understood. In the present study, a new transcriptional regulator, DhyR, was identified. A deletion mutant of dhyR was constructed using the CRISPR-Cas9 tool to elucidate the biological role of DhyR thanks to functional and transcriptomic analyses. The results demonstrated that DhyR positively regulates DAP biosynthesis in S. roseosporus. The in-frame deletion of the dhyR gene resulted in a significant downregulation of the transcription levels of all structural genes within the DAP biosynthetic gene cluster and a significant decrease in DAP yield. In contrast, overexpression of dhyR enhanced the transcription levels of the DAP biosynthetic gene cluster, leading to a 23% increase in DAP yield. Deletion of dhyR caused significant changes in the expression of multiple genes involved in carbohydrate metabolism, energy metabolism and amino acid metabolic pathways through transcriptome analysis. Especially, deletion of dhyR led to a significant downregulation of transcription levels of three DAP biosynthesis-associated genes, including atrA, depR1 and ssig-05090. In summary, DhyR positively regulates DAP biosynthesis in S. roseosporus by influencing the expression of the DAP gene cluster and modulating precursor flux. It functions as a pleiotropic regulator of primary and secondary metabolism in S. roseosporus.

The symbiotic relationship between rhizobia and legumes is critical for sustainable agriculture and has important economic and environmental implications. In this intricate process, rhizobial bacteria colonise plant roots and induce the formation of specialised plant organs, the nodules. Within these structures, rhizobia fix environmental nitrogen into ammonia, significantly reducing the demand for synthetic fertilisers. Multiple bacterial secretion systems (TXSS, Type X Secretion System) are involved in establishing this symbiosis, with T3SS being the most studied. While the Type 6 Secretion System (T6SS) is known as a “nanoweapon” commonly used by diderm (formerly gram-negative) bacteria for inter-bacterial competition and potentially manipulating eukaryotic cells, its precise role in legume symbiosis remains unclear. Sinorhizobium fredii USDA257, a fast-growing rhizobial strain capable of nodulating diverse legume plants, possesses a single T6SS cluster containing genes encoding structural components and potential effectors that could target plant cells and/or act as effector-immunity pairs. Our research reveals that this T6SS can be induced in nutrient-limited conditions and, more importantly, is essential for successful nodulation and competitive colonisation of Glycine max cv Pekin. Although the system did not demonstrate effectiveness in eliminating competing bacteria in vitro, its active presence within root nodules suggests a sophisticated role in symbiotic interactions that extends beyond traditional interbacterial competition.

Science communicators are more critical than ever in a time when misinformation and hoaxes dominate social media, especially during global emergencies like the COVID-19 outbreak. Researchers are good at communicating with peers but often struggle to explain complex ideas to the public. As shown previously, expanding outreach by combining science and art is not only possible, but effective. In the case of microbiology, the synergy between these two apparently divorced areas can help educating our communities and raising microbiological awareness, especially among students. Since Alexander Fleming's pioneering attempts, microorganisms have fascinated artists. Art may help us demystifying microbes and making them more approachable, improving public involvement with science. This article presents two personal experiences using art to teach and communicate scientific ideas (mainly from the microbiology field) to our fellow citizens. Above all, we emphasise the importance of contributing to the scientific literacy of our societies at all ages—including underrepresented and disadvantaged groups—by exploring novel ways to address this gap. By doing so, we align with the concepts and aims of the International Microbiology Literacy Initiative (IMiLI).

Daptomycin (DAP) is a cyclic lipopeptide antibiotic produced by Streptomyces roseosporus, and its biosynthesis is precisely regulated by a complex regulatory network. Although the biosynthetic pathway of DAP has been elucidated, the regulatory mechanism governing its biosynthesis at the transcriptional level is not yet fully understood. In the present study, a new transcriptional regulator, DhyR, was identified. A deletion mutant of dhyR was constructed using the CRISPR-Cas9 tool to elucidate the biological role of DhyR thanks to functional and transcriptomic analyses. The results demonstrated that DhyR positively regulates DAP biosynthesis in S. roseosporus. The in-frame deletion of the dhyR gene resulted in a significant downregulation of the transcription levels of all structural genes within the DAP biosynthetic gene cluster and a significant decrease in DAP yield. In contrast, overexpression of dhyR enhanced the transcription levels of the DAP biosynthetic gene cluster, leading to a 23% increase in DAP yield. Deletion of dhyR caused significant changes in the expression of multiple genes involved in carbohydrate metabolism, energy metabolism and amino acid metabolic pathways through transcriptome analysis. Especially, deletion of dhyR led to a significant downregulation of transcription levels of three DAP biosynthesis-associated genes, including atrA, depR1 and ssig-05090. In summary, DhyR positively regulates DAP biosynthesis in S. roseosporus by influencing the expression of the DAP gene cluster and modulating precursor flux. It functions as a pleiotropic regulator of primary and secondary metabolism in S. roseosporus.