Current Microbiology最新文献

Food Packaging using antibacterial substances plays a vital role in food industry in controlling contamination caused by food borne pathogens. Stability and pH dependent degradation characteristics of zeolitic imidazole framework-8 (ZIF-8) makes its suitable candidate for biomedical applications. The present study focuses on thyme essential oil (TEO) encapsulated in ZIF-8 to achieve a synergistic antibacterial effect and prolonged drug release, aiming to extend the shelf life of food products. Optical, structural and surface characterizations of TEO encapsulated within ZIF-8 (ZIF-8@TEO) reveals successful incorporation of TEO into ZIF-8 nanoparticles. High drug loading and pH dependent release rate with higher release rate at acidic condition (75%) makes ZIF-8 a promising drug delivery system. ZIF-8@TEO exhibited potent antimicrobial against Staphylococcus aureus, Bacillus subtilius and Pseudomonas aeruginosa, also attenuated the biofilm forming ability of these food borne pathogens. In vitro and in vivo toxicity studies reveal the non-hemolytic and non-toxic nature indicating its biocompatible nature. The results of the study reveal that ZIF-8@TEO nanoconjugate can be used for the development of novel antibacterial nanocomposite-based films for food packaging applications.

In recent years, exopolysaccharides (EPSs) from actinomycetes have become a significant focus of research due to their diverse biological activities, including antitumor, antiviral, and immunoregulatory effects. This article reviews recent advancements in the study of EPSs from actinomycetes, summarizing findings from existing literature on extraction methods, structural characteristics, and biological activities. Various extraction methods can impact the purity and quality of EPSs obtained from actinomycetes. In addition, EPSs produced by different species of actinomycetes exhibit diverse structures, leading to variations in their biological activities. Future research should focus on optimizing current extraction methods or developing new techniques, exploring the relationship between structural characteristics and biological activities of EPSs, and elucidating their molecular mechanisms of action. Such efforts are essential for the comprehensive study and potential applications of EPSs from actinomycetes.

A comparative cross-sectional study was conducted on farmed eggs (n: 480) and environmental samples (n: 72; feed, water, and poultry droppings) from twenty-four deep litter and caged poultry layer farms across Punjab, India. The study noted a significantly higher occurrence of Staphylococcus aureus (31.67%; 95% CI 26.37-36.96%) and methicillin-resistant S. aureus (MRSA) (32.5%, 95% CI 23-43.3%) in deep litter farms (P < 0.05). The logistic regression analysis revealed while the odds of presumptive MRSA from egg isolates were high (Odds ratio: 2.714; 95% CI 1.172, 6.284) in deep litter, conversely, resistance against ceftriaxone (0.279; 95% CI 0.129, 0.605), tetracycline (0.227; 95% CI 0.104, 0.497), and erythromycin (0.46; 95% CI 0.218, 0.973) was low. The multi-drug resistance was high and nearly equal; 68.53%, and 72.22% in deep litter and cage systems respectively. Additionally, around 89.65% and 77.7% of MRSA from deep litter and cage systems had multiple antibiotic resistance index > 0.2 respectively. Among the resistance genes under study, the odds of mecA and tetL were 2.417 and 8.029 times higher in deep litter. The hierarchical clustering of MRSA isolates based on the antibiogram profile depicted the formation of a large number of cluster solutions with a mix of isolates from both systems. The SCCmec typing revealed a predominance of type V in both the systems (34.4%; deep litter and 33.3%; cage), with a scarce distribution of other types and subtypes viz., deep litter: types III; 13.7%, IVc; 6.8%, II; 6.8%, IVa, and IVb; 3.4% and cage system: types III and IVc; 11.1%. To, the best of our knowledge current study is the first-ever comprehensive study on comparative occurrence, AMR profile, molecular characterization, and typing of MRSA from farmed eggs and environment from India.

Amylases are pivotal enzymes with extensive industrial applications, including food processing, textile manufacturing, pharmaceuticals, and biofuel production. Traditional methods for enhancing amylase production in microbial strains often lack precision and efficiency. The advent of CRISPR/Cas9 technology has revolutionized genetic engineering, offering precise and targeted modifications to microbial genomes. This review explores the potential of CRISPR/Cas9 for improving amylase production, highlighting its advantages over conventional methods. This review discusses the mechanism of CRISPR/Cas9, the identification and targeting of key genes involved in amylase synthesis and regulation, and the optimization of expression systems. Additionally, current review examines case studies demonstrating successful CRISPR/Cas9 applications in various microbial hosts. The review also delves into the integration of CRISPR/Cas9 in wastewater treatment, where genetically engineered amylolytic strains enhance the degradation of complex organic pollutants. Despite the promising prospects, challenges such as off-target effects and regulatory considerations remain. This review provides a comprehensive overview of the current advancements, challenges, and future directions in the application of CRISPR/Cas9 technology for amylase production and environmental biotechnology.

The genus Streptomyces is a group of gram-positive bacteria that exhibit a distinctive growth pattern characterised by elongated, branched hyphae. Streptomyces coelicolor A3(2), which produces at least five different antibiotics, is a model organism that is widely used in genetic studies. There are very few studies in Streptomyces on the ATP-dependent Lon protease, which has very important functions in every organism and is particularly responsible for protein homeostasis. The aim of this study was to construct and characterize a recombinant S. coelicolor strain expressing the lon gene on a multicopy plasmid. For this purpose, the lon gene was first cloned in Escherichia coli under the control of the glycerol-inducible promoter of pSPG, and its expression in S. coelicolor A3(2) cells was demonstrated by RT-qPCR. In contrast with the initial hypothesis, increased lon expression did not affect cell growth seriously. Instead, it increased the cell's tolerance to osmotic and UV stress and led to a significant increase in antibiotic production. The recombinant strain produced 27 times more actinorhodin and 43 times more undecylprodigiosin than the wild-type strain after 120 h of fermentation. To our knowledge, this is the first study to demonstrate the effects of expression of the lon gene on a high copy number plasmid in Streptomyces.

Tuberculosis (TB) is ranked as the third most prevalent infectious disease globally. Early detection and treatment are crucial for effective management. Conventional diagnostic methods primarily rely on sputum samples, which present challenges in accessibility and have limited accuracy in certain populations such as children, individuals with HIV, and those with extrapulmonary TB. To address the need for point-of-care diagnostics, this study introduces a rapid diagnostic approach for TB using exhaled breath aerosol as a more easily obtainable specimen. Mycobacterium smegmatis, a non-pathogenic bacterium genetically similar to Mycobacterium tuberculosis, is used as a surrogate organism. The method involves the use of microfluidic chips for concentrating and electrolyzing mycobacteria in the aerosol, followed by extracting and quantifying nucleic acids using real-time fluorescence quantitative PCR. Notably, successful enrichment and quantification of bacterial content were achieved even at a minimal bacterial aerosol concentration of 10⁴ CFU/mL. The developed chips are characterized by their cost-effectiveness, ease of use, high bacterial enrichment, efficient nucleic acid extraction, and low detection threshold (4.4 × 10^-18 mol/L). This innovative approach offers a promising method for early TB screening and opens avenues for the rapid identification of other aerosol-transmitted diseases.

Panax notoginseng is an important Chinese medicinal plant. Saponins are the major bioactive secondary metabolites with a wide range of medicinal and commercial value in P. notoginseng, so it is crucial to develop environmentally friendly methods to increase their production. The symbiotic relationship between endophytic bacteria and host plants offers a sustainable approach to enhance secondary metabolite biosynthesis. In this study, it was reported that the co-cultivation of an endophytic bacterium Enterobacter cloacae PN7, isolated from P. notoginseng and its host plant could greatly promote saponin accumulation in the root of seedlings. After six days of PN7 treatment, the total saponin concentration reached 21.64 mg/g, representing a 2.01-fold increase over the control. Transcriptome sequencing revealed that PN7 induction upregulated key genes in the saponin biosynthetic pathway (including DXS, HMGR, PMK, DS, CYP450, and GTs), modulated 253 plant hormone signaling genes (such as those related to JA, ETH, and ABA), and affected 284 transcription factor genes and 47 ABC transporter genes. Co-expression network analysis identified DEGs related to plant hormone signaling, transcription factors, and ABC transporters in saponin biosynthesis and distribution. The results suggested that JA signaling, mediated by transcription factors, such as bHLH and MYBs, and its interaction with ETH, played crucial roles in saponin biosynthesis. Additionally, potential ABC transporter candidates involved in saponin transport were identified. This study highlights the role of endophytic bacteria in enhancing saponin production in P. notoginseng and opens avenues for further research on microbial-plant interactions in secondary metabolite production.

Novel viruses in plants can be detected through transcriptome data mining. In this study, a novel cytorhabdovirus, pear rhabdovirus 1 (PRV-1) was identified through reanalysis of RNA-seq data of pear (P. communis 'Bartlett'). The genomic RNA of PRV-1, with complete coding region, measured 15,628 nucleotides (nts) and encompassed six open reading frames (ORF). Homology analysis of PRV-1 genome showed sequence identity of 33.18-56.75% with the existing cytorhabdovirus sequences. Phylogenetic analysis based on genome sequences showed that PRV-1 clustered in the same clade of cytorhabdoviruses. Based on the sequence demarcation criteria, PRV-1 represents a newly discovered species within the Cytorhabdovirus genus of the Rhabdoviridae family. Identification of a novel virus in pear will enhance our understanding on the diversity of plant cytorhabdoviruses.

Endophytic fungi serve as vital reservoirs of natural products. This study investigates the role of the endophytic fungus, Diaporthe amygdali GWS39, isolated from Geranium wallichianum D. Don Ex Sweet aerial stem. Showing a notable resemblance to Diaporthe amygdali, as confirmed through microscopic, molecular and phylogenetic techniques, this fungal endophyte displays promising antifungal and antioxidant capabilities. Remarkably, the present research marks the first report of D. amygdali as a stem inhabiting endophyte in an herbaceous perennial, Geranium wallichianum D. Don Ex Sweet on a global scale. This study pioneers the documentation of broad-spectrum antifungal activity exhibited by endophyte D. amygdali GWS39 against some economically important pathogens. The antioxidant activity of D. amygdali GWS39 crude extracts showed strong positive correlation, with R² values of 0.99 for the methanolic extract and 0.93 for the ethyl acetate extract, indicating high antioxidant potential. In addition, the current investigation likely signifies the initial record of the bioactive chemical constituents of the endophyte D. amygdali GWS39 using GC-MS. In the GC-MS chromatogram of ethyl acetate extract, cyclohexaneamine, phenol, 2,6, dimethoxy-, benzenesulphonamide, N-(2,6, dimethylphenyl)-2-ethoxy-5-(tetrazol-1-yl), morpholine, 1-, beta, -d-Ribofuranosyl-3-[5-tetraazolyl]-1,2,4, triazole were identified. These compounds are previously reported for potent antibacterial, antifungal, antioxidant, antiviral, anticancer activities. The analysis of methanolic crude extract uncovers the presence of compounds such as arsenous acid tris(trimethylsilyl) ester, n-Hexadecanoic acid, methyl 10,11-octadecadienoate with noted antibiotic, antifungal, anti-inflammatory, antiviral, antihistaminic and anticancer activities.

Dazhu glutinous rice wine is a well-known traditional Chinese rice wine, and many local factories and handicraft workshops use different fermentation methods to produce it. Still, the influence of fermentation processes on glutinous rice wine is unclear. This study aimed to compare the difference between the two fermentation methods in the quality and bacterial composition of Dazhu glutinous rice wine. Results showed that the alcoholic content (P < 0.0001) and acidity (P < 0.01) in the rice wine fermented after packaging (PFRW) were higher than in the rice wine packaged after fermentation (FPRW), but the total sugar content was lower. Most amino, such as glutamic acid proline, and lactic acid were significantly higher in FPRW (P < 0.0001). In addition, the aroma, flavor and taste were better in FPRW than in PFRW. The Limosilactobacillus fermentum, Pediococcus pentosaceus, and Lactococcus lactis were dominant bacteria in FPRW, positively associated with amino acid and lactic acid. At the same time, Alcaligenaceae and Pedobacter nutriment were dominant bacteria in PFRW and negatively correlated with the quality. These implied that lactic acid bacteria significantly contributed to accumulating flavor ingredients and improving the quality of Dazhu glutinous rice wine. This study provides reference data for improving the quality of rice wine.