Microbiology-Sgm最新文献

On 4 June 2025, the MHRA published 'Regulatory considerations for therapeutic use of bacteriophages in the UK'. This was in response to recommendations made by the House of Commons Science, Innovation and Technology Committee Inquiry into the 'The Antimicrobial Potential of Bacteriophages'. The MHRA Regulatory Considerations for phage therapeutic products (PTPs) outlines the relevant regulatory route and requirements to use PTPs as licensed or unlicensed medicines. While this guidance provides the necessary information, it is recognized that regulatory information can be inaccessible to academic and small- to medium-sized enterprise developers who are often unfamiliar with the language, terminology and location of such information. The MHRA, in consultation with the Innovate UK Phage Innovation Network, has therefore developed this interpretation to help PTP developers understand what the guidance is saying, and what evidence is required for regulatory assessment of a marketing authorization application. Examples have been included throughout to provide context and as an aid to understanding.

Ganoderma adspersum is a white-rot wood-degrading basidiomycete of ecological, biotechnological and medicinal interest. In addition to its role in lignin degradation, it produces bioactive metabolites with reported antimicrobial and antioxidant activities. However, the mechanisms of iron acquisition, including siderophore-mediated pathways, remain poorly characterized in Ganoderma species. Improved understanding of these systems is essential to elucidate their contributions to fungal physiology, secondary metabolism and ecological adaptation. In this study, the genome of G. adspersum was sequenced for the first time and screened for genes that may be involved in the production of secondary metabolites. A gene cluster was identified as potentially involved in iron uptake. In particular, genes related to non-ribosomal peptide synthetases were detected next to a gene encoding a monooxygenase and indicated a potential hydroxamate-family siderophore. Liquid chromatography (LC)-ES-MS analysis of secondary metabolites secreted by G. adspersum into the growth medium under iron-limiting conditions revealed a group of previously undescribed siderophores. Genome and MS/MS analysis suggested that these structures might be related to the coprinoferrin family of siderophores. Aside from siderophores, the genome and LC-MS analysis revealed G. adspersum to be a prolific producer of a variety of triterpenoids and sesquiterpenoids, in agreement with previous findings. This is the first description of the genome sequence of G. adspersum and its siderophores.

Bacterial genome engineering has evolved to provide increasingly precise, robust and rapid tools, driving the development and optimization of bacterial production of numerous compounds. The field has progressed from early random mutagenesis methods, labour-intensive and inefficient, to rational and multiplexed strategies enabled by advances in genomics and synthetic biology. Among these tools, CRISPR/Cas has stood out for its versatility and its ability to achieve precision levels ranging from 50% to 90%, compared to the 10-40% obtained with earlier techniques, thereby enabling remarkable improvements in bacterial productivity. Nevertheless, like its predecessors, it still demands continuous refinement to reach full maturity. In this context, the present review addresses the lack of a unified overview by summarizing historical milestones and practical applications of genomic engineering tools in bacteria. It integrates diverse approaches to provide a comprehensive perspective on the evolution and prospects of these fundamental biotechnological tools.

Oligopeptide transporters are important proteins in several lactic acid bacteria (LAB) that facilitate the transport of oligopeptides, the primary nitrogen source for growth in milk. Although the proteolytic mechanisms are well understood in some LAB species, limited research has been conducted on the peptide transport systems of Lacticaseibacillus paracasei (formerly Lactobacillus casei) strain Shirota (LcS), particularly its oligopeptide transporters. This study investigated the nitrogen uptake mechanism of LcS, a probiotic lactic acid bacterium, by generating gene knockout (KO) strains of two oligopeptide transporters, Opp_Lc and Dpp_Lc. Consequently, the disruption of these genes eliminated the ability of the bacterium to grow in milk, identifying Opp_Lc and Dpp_Lc as the primary oligopeptide transporters in LcS. Growth in a leucine-free chemically defined medium with a Leu-containing peptide as the sole nitrogen source indicated that Opp_Lc and Dpp_Lc transport peptides of 4-8 and 3-7 residues, respectively. To our knowledge, this study provides the first experimental evidence of oligopeptide transporters in Lactobacilli capable of transporting peptides up to eight residues long. Analysis of KO strains targeting OppA₁ or DppA₁ to identify other oligopeptide-binding proteins (OBPs) within each oligopeptide transporter operon that may influence substrate specificity revealed that OppA₁ is the only OBPs in Opp_Lc. However, DppA₂ and DppA₃, encoded at chromosomal locations distant from the Dpp_Lc operon, may function as subunits constituting Dpp_Lc and DppA₁. These findings enhance our understanding of nitrogen source utilization in lactobacilli and might inform future strategies to optimize nitrogen sources for LcS and improve culture technology for LcS-based products.

Phage therapy is a promising treatment for multidrug-resistant bacterial infections. Due to their high host specificity, phages must be matched to the target clinical strains. Efficiently identifying appropriate phages and producing sufficient titres for clinical use requires comprehensive phage libraries and multiple propagation hosts. An idealized system would use a highly promiscuous bacterial host to isolate a broader range of phages and streamline optimized phage production. Anti-phage defences constrain bacterial host promiscuity, such as restriction-modification systems that recognize and cleave foreign DNA. Here, the type I restriction endonuclease, HsdR, was deleted from Pseudomonas aeruginosa PAO1 to make a more promiscuous phage isolation and propagation host. Removal of this endonuclease more than doubled the efficiency of phage propagation on solid media, improved yields from hard-to-propagate phages in liquid bulk-ups and yielded seven times more phages from freshwater samples than wild-type PAO1 - an important step in producing an optimized P. aeruginosa strain for isolating and propagating phages for clinical phage therapy.

Antimicrobial resistance is a massive threat, but developing a new antibiotic can take decades. That time could be drastically reduced if we were able to anticipate desirable properties of a chemical, such as its potential to target specific bacterial compartments. This would provide the opportunity to prioritize the development of molecules that target, for instance, the cell membrane, as this does not rely on transporters and usually results in a fast-acting bactericidal effect. We used flow cytometry and a set of fluorophores together with a group of antibiotics to discriminate between antimicrobials acting on cell membrane versus intracellularly against two Gram-negative bacteria, Escherichia coli and Acinetobacter baylyi. We then chose Rhodamine 123 as a fluorescent marker to screen a commercial library of chemical compounds. Using flow cytometry, several drugs present in the Prestwick library were observed to have cytotoxic effects at 1 µM final concentration towards E. coli. This was confirmed with growth inhibitory assays in both E. coli and A. baylyi for pantoprazole, theophylline and zoledronic acid. This represents an approach to the large-scale screening of small molecules with the potential to deliver fast-acting molecules that target cell membranes in Gram-negative bacteria.

Streptomyces formicae KY5 was isolated from a Tetraponera penzigi plant-ant nest. It is primarily known for its production of the formicamycins, antibiotics with potent activity against Gram-positive pathogens including methicillin-resistant Staphylococcus aureus, and additionally produces an antifungal compound that inhibits multi-drug-resistant fungal pathogens including Lomentospora prolificans. S. formicae is genetically tractable using CRISPR-Cas9 gene editing, allowing for detailed analysis of the formicamycin biosynthetic gene cluster. AntiSMASH analysis predicts the genome to encode at least 45 secondary metabolite biosynthetic gene clusters, many of which appear to encode novel compounds. Current research efforts are focussing on characterising the regulation of secondary metabolism at a global level in order to switch on pathways that are not typically expressed under standard laboratory conditions with the aim of identifying novel antimicrobials.

Consumers' healthy lifestyle practices have heightened the appeal of minimally processed foods, especially the fermented kind. Kefir and nabeez with numerous benefits are world-famous beverages. This study aimed to explore the enterococcal and lactococcal probiotic strains associated with these beverages. Artisanal recipes were used to make kefir and nabeez, and bacteria were isolated using classical culturing techniques. The isolates were screened based on antimicrobial potential, safety and probiotic attributes. The bacterial isolates obtained from three fermented beverages, milk kefir, water kefir and nabeez, were assessed for safety concerns, and those deemed safe were tested for antagonistic potential. Strains of Enterococcus durans (NPL1395_MK, NPL1396_MK and NPL1480_MK), Enterococcus faecium (NPL1390_MK, NPL1420_WK and NPL1427_Nb) and Lactococcus lactis (NPL1426_Nb, NPL1428_Nb and NPL1436_Nb) demonstrated interesting antimicrobial characteristics against food-borne pathogens. Strains from milk kefir and nabeez could tolerate strong acidic and bile stress. All strains were susceptible to lysozyme and phenol at the concentrations tested but demonstrated significant antioxidant potentials, exopolysaccharide production and bile salt hydrolase activities. Cholesterol assimilation was most significant in milk kefir and nabeez strains, which also had good adherence and biofilm formation. Statistical analysis of performance data using the principal component analysis identified L. lactis strain NPL1428_Nb as the best. It exhibited good potential to persist in the human gut based on its ability to tolerate in vitro mixtures simulating the gastrointestinal tract digestive fluids, using the static digestion model. Therefore, strain NPL1428_Nb of traditional fermented beverage provenance has good prospects for use in probiotic product development.

A session at the annual conference of the Microbiology Society 2025 (Liverpool) was held on gaining impact from basic and applied research, 'Beyond the lab - Turning your research into reality'. This Commentary provides a short description of the rationale behind the session, the key take-home messages, information on the speakers and key resources they shared with the microbiology community.

Seaweeds are a common and diverse component of coastal ecosystems and are known to be associated with Escherichia coli due to faecal pollution. As a biotic substrate, beach-cast seaweed may affect bacterial physiology and thereby horizontal gene transfer (HGT). Here, we test how the presence of three distinct senescing seaweed species affects E. coli plasmid conjugation. We allow the IncP plasmid pKJK5 to conjugate while supplying a substrate of Palmaria palmata (dulse), Ulva lactuca (sea lettuce) or Fucus serratus (serrated wrack). The three seaweed species induce distinct conjugative behaviours in E. coli: U. lactuca has no significant impact relative to a plastic control, the presence of F. serratus results in undetectable levels of conjugation and P. palmata promotes conjugation in a density-independent manner. This study highlights how biotic interactions can influence survival, HGT and antibiotic resistance in a human pathogen.