Canadian journal of microbiology最新文献

Bacteria encounter various stressful conditions within a variety of dynamic environments, which they must overcome for survival. One way they achieve this is by developing phenotypic heterogeneity to introduce diversity within their population. Such distinct subpopulations can arise through endogenous fluctuations in regulatory components, wherein bacteria can express diverse phenotypes and switch between them, sometimes in a heritable and reversible manner. This switching may also lead to antigenic variation, enabling pathogenic bacteria to evade the host immune response. Therefore, phenotypic heterogeneity plays a significant role in microbial pathogenesis, immune evasion, antibiotic resistance, host niche tissue establishment, and environmental persistence. This heterogeneity can result from stochastic and responsive switches, as well as various genetic and epigenetic mechanisms. The development of phenotypic heterogeneity may create clonal populations that differ in their level of virulence, contribute to the formation of biofilms, and allow for antibiotic persistence within select morphological variants. This review delves into the current understanding of the molecular switching mechanisms underlying phenotypic heterogeneity, highlighting their roles in establishing infections caused by select bacterial pathogens.

The use of Trichoderma in agriculture as both a biocontrol agent and biofertilizer hinges on its ability to colonize the rhizosphere, promote plant growth, endure adverse environments, compete for space and nutrients, and produce enzymes and secondary metabolites to mycoparasitize and infect other fungus. In humans, Trichoderma exhibits the capacity to infect various bodily tissues, leading to Trichodermosis. There has been a notable increase in cases ranging from superficial to fatal, invasive, and disseminated infections, particularly among immunocompromised individuals. Trichoderma species employ diverse strategies to colonize and survive in various environments, infecting phytopathogens; however, the mechanisms and virulence factors contributing to human infections remain poorly understood. In this mini review, we provide a brief overview and contextualization of the virulence mechanisms employed by Trichoderma in parasitizing other fungi, as well as those implicated in modulating plant immunity and inducing human infections. Furthermore, we discuss the similarity of these virulence factors capable of modulating the mammalian immune system and their potential implications for human infection.

Rhizobia are soil-dwelling proteobacteria that can enter into symbiotic nitrogen-fixing relationships with compatible leguminous plants. Taxonomically, rhizobia are divided into alpha-rhizobia, which belong to the class Alpharoteobacteria, and beta-rhizobia, which belong to the class Betaproteobacteria. To date, all bona fide alpha-rhizobia belong to the order Hyphomicrobiales. However, a recent study suggested that Sphingomonas sediminicola DSM 18106^T is also a rhizobium and is capable of nodulating pea plants (Pisum sativum), which would expand the known taxonomic distribution of alpha-rhizobia to include the order Sphingomonadales. Here, we attempted to replicate the results of that previous study. Resequencing and computational analysis of the genome of S. sediminicola DSM 18106^T failed to identify genes encoding proteins involved in legume nodulation or nitrogen fixation. In addition, experimental plant assays indicated that S. sediminicola DSM 18106^T is unable to nodulate the two cultivars of pea tested in our study, unlike the rhizobium Rhizobium johnstonii 3841^T. Taken together, and in contrast to the previous study, these results suggest that S. sediminicola DSM 18106^T is not capable of inducing root nodule formation on pea, meaning that the taxonomic distribution of all known alpha-rhizobia remains limited to the class Hyphomicrobiales.

On solid substrates, biofilms develop rich wrinkle morphologies during its growth. Based on the thin film buckling theory, we established a local three-dimensional biofilm/substrate buckling model, and explored the effects of mechanical forces, elastic modulus of the substrate, and biofilm thickness on the wrinkle morphology. We simulated the wrinkle evolution in various patterns of Bacillus subtilis biofilm growing on agar substrates with different stiffness and found that the biofilm wrinkling process is the process of internal energy release. The stiffness of the substrate changes the wrinkling time of the biofilm; The biofilm wrinkle morphology (patterns II, III, and IV) U_internal and U_internal/U₀ decrease with nutrient consumption, and the biofilm evolves towards lower energy consumption. In the early stages of biofilm growth (patterns I, II, and III), the harder the agar substrate, the larger the U_friction and U_friction/U₀, which is less conducive to biofilm expansion.

DNA synthesis and assembly techniques have enabled the creation of validated and standardized DNA parts, used for producing proteins, enzymes, and small molecules. However, most DNA parts are governed by Material Transfer Agreements, which restrict sharing and reuse for commercial purposes even in the absence of patents, bottlenecking innovation. DNA synthesis, crucial for producing new parts, also remains expensive and therefore inaccessible to most researchers. With the breakneck pace of digital innovations for designing and learning from biology, a new and more open approach to the physical building and testing of biology is needed. We propose the establishment of an Open Bio Research Alliance, to create and distribute open collections of DNA and other biological parts, combined with regulated and affordable DNA synthesis services. Focusing on Canada's bioeconomy, establishing domestic DNA synthesis infrastructure would not only secure global competitiveness in engineering biology, but also safeguard biosecurity and national sovereignty over critical resources. By harnessing and supporting existing lab automation resources, the Alliance will also help scale the building and testing of engineered biological systems. Leveraging these tools and strategies, Canada is well-positioned to lead the world in open and innovative biotechnology, paving the way for a thriving bioeconomy.

As it flows through the collection system, maple sap is likely to be contaminated by microorganisms that colonize the tubing, potentially compromising its quality in terms of physicochemical properties, microbial load, and flavor. This study investigates the effect of microbial inoculation, as protective cultures, on the sap collection system to improve maple syrup quality. The research explored how inoculating collection tubing with specific bacterial strains influences the microbial composition, physicochemical properties (pH, Brix, conductivity, sugars, and organic acids content), and sensory attributes of both maple sap and syrup. Three strains selected for their capacity to produce biofilm on plastic tubing and their impact on maple syrup production from inoculated sap, Pseudomonas sp. MSB2019, Janthinobacterium lividum 100-P12-9, and Pseudomonas fluorescens ATCC 17926, were inoculated to independent sap collection system throughout two sugaring seasons. A non-inoculated system was included. Pseudomonas sp. MSB2019 treatment resulted in a distinct bacterial composition in sap and impact the organoleptic properties of syrup by the end of second flow season, particularly the maple and overall flavor intensity scores were higher. While sap yield and primary microbial load remained unaffected, inoculation treatments corresponded to shifts in flavor attributes of the syrup. These findings indicate that inoculating sap collection systems with targeted strains can positively influence maple syrup quality, particularly in enhancing desirable flavor profiles, suggesting promising applications for syrup production.

Many arthropods, including economically important pests of stored grains, host intracellular bacterial symbionts. These symbionts can have diverse impacts on host morphology, stress tolerance, and reproductive success. The ability to rapidly determine the infection status of host insects and the identity of intracellular symbionts, if present, is vital to understanding the biology and ecology of these organisms. We used a microbiome profiling method based on amplicon sequencing to rapidly screen 35 captive insect colonies. This method effectively revealed single and mixed infections by intracellular bacterial symbionts, as well as the presence or absence of a dominant symbiont, when that was the case. Because no a priori decisions are required about probable host-symbiont pairing, this method is able to quickly identify novel associations. This work highlights the frequency of endosymbionts, indicates some unexpected pairings that should be investigated further, such as dominant bacterial taxa that are not among the canonical genera of endosymbionts, and reveals different colonies of the same host insect species that differ in the presence and identity of endosymbiotic bacteria.

M13 bacteriophages form self-assembled nanorods with the ability to self-assemble into complex materials with higher-order structures. These features make them useful templates for material fabrication. Their use in soft materials, bio-nano systems, and biomedical applications is well established. For these bio-interfacial applications, it is crucial that phages remain biocompatible and their production sustainable. Here, we review the bioprocessing of M13 phages and genetic engineering strategies that retain their natural assets in nanomaterials or bulk materials. Specifically, we highlight the extensively studied fermentation process of M13 phages with Escherichia coli (E. coli) and common downstream processing methods suitable for materials manufacturing. The ease of phage production contributes to its wide use for phage display, enabling the creation of large libraries of functional mutants. For materials purposes, genetic engineering often targets the pIII and pVIII proteins, enabling different geometries and fragment sizes. We also review common peptides displayed on phages, including arginine-glycine-aspartic acid (RGD) peptides, used for surface plasmon resonance (SPR) probes, targeted medicine, cell regeneration, or tissue scaffolding. We study glutamate-modified phages for metal binding, biomineralization, and electronics in bulk materials. By considering self-assembly, bioprocessing, and genetic engineering, material engineers can fully harness M13 phages for diverse functional and sustainable devices.

Pyrimidine base and ribonucleoside salvage metabolism was investigated in Pseudomonas putida ATCC 17536 cells. In ATCC 17536 cell extracts, the pyrimidine ribonucleoside salvage enzymes nucleoside hydrolase and cytosine deaminase activities were measurable, while uridine phosphorylase activity was not. Carbon and nitrogen sources influenced the levels of the salvage pathway enzyme activities in P. putida ATCC 17536. Catabolite repression by a glucose metabolite of nucleoside hydrolase and cytosine deaminase synthesis in ATCC 17536 cells compared to cells grown on the carbon source succinate or ribose was observed, while a nitrogen metabolite appeared to be controlling pyrimidine salvage enzyme synthesis. When glucose was the carbon source, ATCC 17536 cells grown on uracil or 5-methylcytosine as a nitrogen source caused at least a five-fold increase in hydrolase and deaminase synthesis relative to their activities in ammonium sulfate-grown cells. In succinate-grown ATCC 17536 cells, thymine or 5-methylcytosine as a nitrogen catabolite produced at least double the hydrolase or deaminase activity relative to either activity in ammonium sulfate-grown cells. Overall, the pyrimidine base and ribonucleoside salvage enzymes in P. putida ATCC 17536 biovar B cells were regulated by the carbon or nitrogen source with pyrimidine salvage metabolism differing in biovar A and B strains.