Research in microbiology最新文献

Nocardiopsis dassonvillei prevails under harsh environmental conditions and the purpose of this review is to highlight its biological features and recent biotechnological applications. The organism prevails in salt-rich soils/marine systems and some strains endure extreme temperatures and pH. A few isolates are associated with marine organisms and others cause human diseases. Comparative genomic analysis indicates its versatility in producing biotechnologically relevant metabolites. Antimicrobial, cytotoxic, anticancer and growth promoting biomolecules are obtained from this organism. It also synthesizes biotechnologically important enzymes. Bioactive compounds and enzymes obtained from this actinomycete provide evidence regarding its metabolic competence and its potential economic value.

Medical students could be a potential source of Staphylococcus aureus transmission to patients. This cross-sectional study involved samples collected from both nasal nostrils. Samples were processed for S. aureus recovery; the antimicrobial resistance (AMR) phenotype was determined by disc diffusion assays and the spa types and AMR genotypes by PCR/sequencing. A structured questionnaire was administered to students to collate data related to potential risk factors of nasal colonization. Ninety-eight students were included, 50 % were colonized by S. aureus and 12.2 % by MRSA. The mecA gene was detected in all MRSA isolates. The MSSA-CC398-IEC-type C lineage was found among 16.3 % of nasal carriers, of which t571 was the predominant spa-type. MRSA isolates were ascribed to spa types t2226 (CC5, 12 isolates) and t3444 (new spa type, 1 isolate). All MRSA were multi-drug resistant and MSSA were predominantly resistant to erythromycin-clindamycin (inducible-type, mediated by ermT gene). High rates of S. aureus and MRSA nasal carriages were observed in this study. The predominance of the CC398 lineage among MSSA (emergent invasive lineage) represent a relevant finding of public health concern. The role of medical students as potential source of MRSA and MSSA-CC398 transmissions in hospital and community needs to be elucidated in detail.

This review summarizes the literature on efficacy of techniques to sterilize soil. Soil may need to be sterilized if contaminated with pathogens such as Bacillus anthracis. Sterilizing soil in-situ minimizes spread of the bio-contaminant. Soil is difficult to sterilize, with efficacy generally diminishing with depth. Methyl bromide, formaldehyde, and glutaraldehyde are the only soil treatment options that have been demonstrated at full-scale to effectively inactivate Bacillus spores. Soil sterilization modalities with high efficacy at bench-scale include wet and dry heat, metam sodium, chlorine dioxide gas, and activated sodium persulfate. Simple oxidants such as chlorine bleach are ineffective in sterilizing soil.

Proteus mirabilis is known to cause Catheter-associated urinary tract infections (CAUTIs), which exhibit virulence factors linked to forming biofilms. Aptamers have recently been explored as potential anti-biofilm agents. This study demonstrates the anti-biofilm activity of aptamer (PmA2G02) targeting P. mirabilis 1429^T, a pathogenic bacteria known to cause Catheter-associated urinary tract infections (CAUTIs). The studied aptamer inhibited biofilm formation, swarming motility, and cell viability at a concentration of 3 μM. The study also showed that the PmA2G02 had a binding affinity towards fimbrial outer membrane usher protein (PMI1466), flagellin protein (PMI1619), and regulator of swarming behavior (rsbA), which are responsible for adhesion, motility, and quorum sensing, respectively. Crystal violet assay, SEM, and confocal imaging confirmed the effectiveness of the PmA2G02 as an anti-biofilm agent. Moreover, as verified by qPCR, the expression levels of fimD, fliC2, and rsbA were significantly reduced compared to the untreated group. This study suggests that aptamer may be a potential alternative to traditional antibiotics for the treatment of CAUTIs caused by P. mirabilis. These findings shed light on the mechanisms by which the aptamer inhibits biofilm formation.

Biofilms have been recognized as a serious threat to public health as it protects microbes from antimicrobials, immune defence mechanisms, chemical treatments and nutritional stress. Biofilms are also a source of concern in industries and water treatment because their presence compromises the integrity of equipment. To overcome these problems, it is necessary to identify novel anti-biofilm compounds. Products of microorganisms have been identified as promising broad-spectrum anti-biofilm agents. These natural products include biosurfactants, antimicrobial peptides, enzymes and bioactive compounds. Anti-biofilm products of microbial origin are chemically diverse and possess a broad spectrum of activities against biofilms. The objective of this review is to give an overview of the different types of microbial anti-biofilm products and their mechanisms of action.

There are many different kinds of microorganisms in the soil, and many of them are biofilms because they can make supracellular compounds. Surface-associated microorganisms in a biofilm are encased in a hydrated extracellular polymeric substance that aids in adherence and survival. Numerous different kinds of microorganisms call the soil home. Strong interactions with and among species are made possible by biofilms; this, in turn, might increase the effectiveness with which organic compounds and poisons in soil are degraded. This encouraged us to take a close look at soil biofilm ecosystems, which we do in this paper. In this research, we will look at how soil biofilms arise and how that affects the composition of microbial communities and their function in the soil. Recent years have seen an uptick in interest in questions about biofilm structure and the social interactions of various bacteria. Many concepts elucidating the underlying mathematics of biofilm growth are also presented. Since biofilms are so widespread, this breakthrough in soil biofilm inquiry might help scientists understand soil microbiomes better. Mathematical models further extrapolate the relationships between microbial communities and gives a more precise information as to what is happening in a biofilm. Biofilms can help plants cope with a variety of environmental challenges. Soil quality, plant nourishment, plant protection, bioremediation, and climate change are all influenced by the interplay of biofilm communities. Thus, biofilms play an important role in the development of environmentally friendly and sustainable agriculture.

Bacteria are ubiquitous prokaryotes. They are involved in biofilm formation and also have the ability to produce anti-biofilm products for biofilm mitigation. This special issue entitled: “Biofilms- community structure, applications and mitigation” of the journal Research in Microbiology was designed to discuss the flexibility of bacterial biofilms and their products under particular circumstances. Given that quorum sensing (QS) controls biofilm growth in some situations, especially for pathogenic bacteria antibiotic evading strategies. In Gram-negative bacteria, N-acyl homoserine lactones are the major quorum sensing signaling molecules. Another approach to prevent bacterial biofilm formation may be to inhibit the QS-regulated activities using quorum quenching (QQ). In this context, QS inhibitors and QS enzymes are important because they, respectively, interfere with signal creation, perception, or degradation and chemical modification. There have been numerous reports of QQ enzymes from bacteria. Treatment failure and recurrent staphylococcal infections are also brought on by biofilm development, which boosts an organism's ability to withstand antibiotics and is thought to be a virulence factor in patients. However, polyphenol quercetin antibiofilm activity is naturally available against drug-resistant Staphylococcus aureus.

Wastewater often contains an increased amount of mercury and, at the same time, resistant microorganisms. During wastewater treatment, a biofilm of indigenous microorganisms is often unavoidable. Therefore, the objective of this research is to isolate and identify microorganisms from wastewater and investigate their ability to form biofilms for possible application in mercury removal processes.

The resistance of planktonic cells and their biofilms to the effects of mercury was investigated using Minimum Biofilm Eradication Concentration-High Throughput Plates. The formation of biofilms and the degree of resistance to mercury were confirmed in polystyrene microtiter plates with 96 wells. Biofilm on AMB Media carriers (Assisting Moving Bad Media) was quantified using the Bradford protein assay. The removal of mercury ions by biofilms formed on AMB Media carriers of selected isolates and their consortia was determined by a removal test in Erlenmeyer flasks simulating MBBR.

All isolates in planktonic form showed some degree of resistance to mercury. The most resistant microorganisms (Enterobacter cloacae, Klebsiella oxytoca, Serratia odorifera, and Saccharomyces cerevisiae) were tested for their ability to form biofilms in the presence and absence of mercury, both in polystyrene plates and on ABM carriers. The results showed that among planktonic forms, K. oxytoca was the most resistant. A biofilm of the same microorganisms was more than 10-fold resistant. Most consortia biofilms had MBEC values > 100,000 μg/mL. Among individual biofilms, E. cloacae showed the highest mercury removal efficiency (97.81% for 10 days). Biofilm consortia composed of three species showed the best ability to remove mercury (96.64%–99.03% for 10 days).

This study points to the importance of consortia of different types of wastewater microorganisms in the form of biofilms and suggests that they can be used to remove mercury in wastewater treatment bioreactors.

Quorum sensing (QS) is the ability of bacteria to monitor their population density and adjust gene expression accordingly. QS-regulated processes include host–microbe interactions, horizontal gene transfer, and multicellular behaviours (such as the growth and development of biofilm). The creation, transfer, and perception of bacterial chemicals known as autoinducers or QS signals are necessary for QS signalling (e.g. N-acylhomoserine lactones). Quorum quenching (QQ), another name for the disruption of QS signalling, comprises a wide range of events and mechanisms that are described and analysed in this study. In order to better comprehend the targets of the QQ phenomena that organisms have naturally developed and are currently being actively researched from practical perspectives, we first surveyed the diversity of QS-signals and QS-associated responses. Next, the mechanisms, molecular players, and targets related to QS interference are discussed, with a focus on natural QQ enzymes and compounds that function as QS inhibitors. To illustrate the processes and biological functions of QS inhibition in microbe–microbe and host–microbe interactions, a few QQ paradigms are described in detail. Finally, certain QQ techniques are offered as potential instruments in a variety of industries, including agriculture, medical, aquaculture, crop production, and anti-biofouling areas.

Staphylococcus aureus is typically treated with antibiotics, however, due to its widespread and unselective usage, resistant strains of S. aureus have increased to a great extent. Treatment failure and recurring staphylococcal infections are also brought on by biofilm development, which boosts an organism's ability to withstand antibiotics and is thought to be a virulence factor in patients. The present study investigates the antibiofilm activity of naturally available polyphenol Quercetin against drug-resistant S. aureus. Micro dilution plating and tube adhesion methods were performed to evaluate the antibiofilm activity of quercetin against S. aureus. Quercetin treatment resulted in remarkably reduction of biofilm in S. aureus cells. Further we performed a study to investigate binding efficacies of quercetin with genes icaB and icaC from ica locus involved in biofilm formation. 3D structure of icaB, icaC and quercetin were retrieved from Protein data bank and PubChem chemical compound database, respectively. All computational simulation were carried out using AutoDock Vina and AutoDockTools (ADT) v 1.5.4. In silico study demonstrated a strong complex formation, large binding constants (K_b) and low free binding energy (ΔG) between quercetin and icaB (K_b = 1.63 × 10⁻⁵, ΔG = −7.2 k cal/mol) and icaC (K_b = 1.98 × 10⁻⁶, ΔG = −8.7 kcal/mol). This in silico analysis indicates that quercetin is capable of targeting icaB and icaC proteins which are essential for biofilm formation in S. aureus. Our study highlighted the antibiofilm activity of quercetin against drug resistant pathogen S.aureus.