Current Microbiology最新文献

In recent years, there has been a global threat from emerging vector-borne diseases (VBD), despite the implementation of several vector control programs. Considering the benefits of bacterial pesticides, the present study aimed to isolate potential mosquitocidal bacteria from the various soil types collected from the Kasaragod (12.5°N, 75.0°E) district of Kerala, India. One bacterial strain was isolated from the coastal alluvium soil and showed promising mosquitocidal activity. The mosquitocidal isolate was identified as Bacillus thuringiensis serovar israelensis strain VCRC-B649 through phylogenetic analysis of whole genome sequence. LC₅₀ values against Culex quinquefasciatus, Aedes aegypti, and Anopheles stephensi larvae were determined as 0.0064, 0.0072, and 0.0101 mg/L, and LC₉₀ values were 0.0127, 0.0140, and 0.019 mg/L. Comparative analysis of larvicidal activity of this strain has revealed more efficacy than the WHO reference strain of B. thuringiensis var. israelensis (H14) The cry and cyt gene profile of this isolate is found to be similar to WHO reference strain of B. thuringiensis var. israelensis (H14). This new isolate has not shown any adverse effects against aquatic non-target organisms. Further evaluation of its morphological, biochemical characteristics and growth kinetics revealed similarities with already reported B. thuringiensis strains. Sporulated culture at 72 h showed maximum (20.6 ± 1.5 mm) proteolytic activity and animal skin (goat skin) dehairing property and revealed the industrial applications of this new strain. This is the first report on the isolation of mosquitocidal bacterial strain with enzyme-producing property from the Malabar coastal region and it was proven to be a more suitable alternative biocontrol agent for controlling the disease transmitting mosquito vectors with translational value.

An aerobic, Gram-stain-positive, motile, coccus-shaped actinomycete, designated strain LSe6-4^T, was isolated from leaves of sea purslane (Sesuvium portulacastrum L.) in Thailand and subjected to a polyphasic taxonomic studies. Growth of the strain occurred at temperatures between 15 and 38 °C, and with NaCl concentrations 0-13%. The 16S rRNA gene sequences analysis indicated that the strain was most closely related to Kineococcus endophyticus KLBMP 1274^T (99.2%), and Kineococcus mangrovi L2-1-L1^T (99.0%). The genome of strain LSe6-4^T was estimated to be 4.22 Mbp in size, with DNA G+C content of 74.57%. The average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) relatedness values between strain LSe6-4^T and the closely related species were less than the threshold values for identifying a novel species. Strain LSe6-4^T showed morphological and chemotaxonomic characteristics of the genus Kineocoocus. The whole-cell hydrolysates contained meso-diaminopimelic acid as the diagnostic diamino acid, with arabinose, galactose, and ribose as whole-cell sugars. The predominant menaquinone was MK-9(H₂). The polar lipid profile composed of phosphatidylglycerol, diphosphatidylglycerol, an unidentified phospholipid, three unidentified aminophospholipids, and an unidentified aminolipid. Major cellular fatty acids (> 10% of total fatty acids) were anteiso-C_15:0 and iso-C_14:0. It is evident from the combination of genotypic and phenotypic characteristics that strain LSe6-4^T represents a novel species of the genus Kineococcus, for which the name Kineococcus halophytocola sp. nov. is proposed. The type strain is strain LSe6-4^T (= TBRC 17798^T = NBRC 116401^T).

Antimicrobial resistance (AMR) is an escalating global health concern that results in approximately 700,000 deaths annually owing to drug-resistant infections. It compromises the effectiveness of conventional antibiotics, as well as fundamental medical procedures, such as surgery and cancer treatment. Phytochemicals, natural plant constituents, and biogenic nanoparticles synthesized through biological processes are pharmacological alternatives for supplementing or replacing traditional antibiotics. These natural compounds exhibit a diverse range of bioactive properties, including antibacterial, anti-inflammatory, and antioxidant activities, and have the potential to overcome bacterial resistance mechanisms. However, their limited solubility, bioavailability, and stability have limited their therapeutic potential. Nanotechnology, particularly the utilization of biogenic nanoparticles, offers the potential to overcome these limitations by enhancing the biosafety, stability, and controlled release of phytochemical compounds, thereby enabling a more effective combination of resistant pathogens. This review examines current research on the combinatorial application of phytochemicals and biogenic nanoparticles, with emphasis on their capacity to address AMR. This study presents a novel perspective on the concurrent utilization of phytochemicals and biogenic nanoparticles, which may enhance antibacterial efficacy while mitigating toxicity. This review provides specific and innovative insights into the novelty, sustainability, and eco-friendly aspects of these approaches to address multidrug-resistant infections, highlighting their role in emerging as a transformative strategy for AMR management through the integration of natural and biogenic resources.

Gut mucosal immunity of teleost is mainly governed by mucosa-associated lymphoid tissues (MALT) and indigenous microbiota on mucosal surfaces of gut tract, which can confer protection against pathogenic invasion. However, the probiotic features of bacterial isolates from gut tract of triploid cyprinid fish (TCF) were largely unclear. In this study, Lysinibacillus and Enterobacter strains were isolated for probiotic identification. Whole genome sequencing (WGS) analysis indicated that Lysinibacillus and Enterobacter isolates possessed a variety of functional genes associated with probiotic features. Biofilm-forming activity (BFA) were one of the most important probiotic features, which can enable probiotic strains to communicate with indigenous microbiota by forming sessile community and then confer protection against stressors and invading pathogens. In this study, Lysinibacillus and Enterobacter isolates displayed high levels of BFA, hydrophobicity as well as aggregating potentials. Moreover, supernatants of probiotic isolates not only decreased pathogenic BFA and growth activity, but also showed high decomposing activity to macronutrients. These results indicated that probiotic isolates from gut tract of TCFs may pose protective roles in health of farmed fish.

This research was conducted to determine the relationship between plant defense responses and the extent of treatment applied to either the aerial parts or roots of the plant. The experimental treatments included different methods of application (spraying versus soil drenching), varying treatment areas (one-sixth, one-third, half, or all of the plant's aerial parts and roots) with SA, and infecting the plants with root-knot nematodes. Evaluation of plant growth and nematode pathogenicity indices in the greenhouse section, H₂O₂ accumulation rate, and phenylalanine ammonia lyase enzyme activity (in aerial parts and roots) were carried out in biochemical experiments. The results showed that treating less than one-third of the aerial parts with salicylic acid (SA) did not significantly impact plant growth or nematode pathogenicity indices. However, it did lead to a notable increase in hydrogen peroxide (H₂O₂) accumulation, while phenylalanine ammonia lyase (PAL) enzyme activity remained unchanged. In contrast, treating more than one-third of the aerial parts resulted in decreased nematode pathogenicity and enhanced production of defense compounds. Notably, treatments targeting the roots consistently demonstrated a more pronounced effect on nematode suppression and increased defense compound levels, emphasizing the importance of root treatment, as this is where nematodes are primarily present. Overall, the study highlights the differential impact of treatment location and extent on plant defense mechanisms and suggests that strategic targeting of either aerial or root tissues can optimize plant responses against nematode attacks.

The severe climate change has caused a drastic water level disparity around the globe, which eventually has been one of the biggest problems of this era related to land degradation. This has caused the multidimensional impact on ecology, the environment, and their components. Algae, one of the ancient micro-engineers, are involved in the functioning of soil microcosm. Therefore, this study has utilized a novel alga, Chlorella vulgaris SSAU8 to observe the impact of low water potential induced by PEG-6000 (polyethylene glycol). The study has utilized the UV-Vis spectrophotometer to explore the nature of cyanobacteria by examining biomass and pigment concentrations. The assessment also includes the photosystem response, which was recorded by the Dual-modulation kinetic fluorometer FL3500/F (PSI, Brno, Czech Republic, version 3.7.0.1). The effect of PEG-6000-induced drought was seen to inhibit growth and biomass synthesis at > 30 g L^-1 concentration. It was also observed that the microbe could easily shuffle its photosystem behavior to nullify the effect of high PEG-6000 concentration, which shows the potential of the microbe in the water-deficient area and can be an important aspect to enhance soil fertility. Non-photochemical quenching and heat dissipation play a crucial role in cyanobacteria tolerating drought conditions. So, overall, this study thoroughly explores the behavior of Chlorella vulgaris SSAU8 in artificial drought stress and paves a way to combat one of the major environmental issues of the current era.

The present study explores the microbial community associated with the industrially important red seaweed Gracilaria dura to determine the diversity and biotechnological potential through culture and metagenomics approaches. In the first part of the investigation, we isolated and characterized 75 bacterial morphotypes, with varied colony characteristics and metabolic diversity from the wild seaweed. Phylogenetic analysis identified isolates in Proteobacteria, Firmicutes, and Actinobacteria, with Bacillus sp. being prevalent. B. licheniformis and Streptomyces sp. were notable in producing important enzymes like L-asparaginase, and polysaccharide lyases. Antimicrobial activity was significant in 21% of isolates, effective against seaweed pathogens such as Vibrio and Xanthomonas. Rhodococcus pyridinivorans showed strong pyridine degradation, suggesting bioremediation potential. Several isolates exhibited phosphate solubilization and nitrate indicating the roles of bacteria as algal growth promoters and biocontrol agents. Subsequent metagenome analysis of wild and cultured samples provides insights into bacterial communities associated with G. dura, revealing their distribution and functional roles. Proteobacteria (~ 95%) dominated the communities, further bacterial groups involved in algal growth, carpospore liberation, stress resistance, biogeochemical cycles, and biomedical applications were identified. A notable difference in bacteriomes was observed between the samples, with 25% remaining stable. The samples are cultured in the lab to generate seedlings for farming and serve as germplasm storage during the monsoon season. Microbiome surveys are crucial for understanding the association of pathogens and the overall health of the seedlings, supporting successful seaweed farming. Our findings provide valuable insights into G. dura-associated microbial communities and their role in algal growth, which has aquacultural implications.

A facultative anaerobic, Gram-stain-negative, non-motile, rod-shaped bacterial strain AGMB14963^T was isolated from the feces of a dairy cow. A 16S rRNA gene sequence-based phylogenetic analysis revealed that strain AGMB14963^T belongs to the genus Gallibacterium, with Gallibacterium salpingitidis F150^T being the closest species (95.8% 16S rRNA gene sequence similarity). Whole-genome sequence analysis revealed that strain AGMB14963^T had a 37.0% G + C genomic DNA content and a genome size of 2.58 Mb. In addition, the strain contained 53 tRNA and 2 rRNA genes. The average nucleotide identity and digital DNA-DNA hybridization values between strains AGMB14963^T and G. salpingitidis F150^T were 82.3 and 24.9%, respectively. Further, strain AGMB14963^T was positive for oxidase and catalase, but negative for urease. Optimal growth of strain AGMB14963^T occurred at 37 ℃, pH 8, and in 0.5% NaCl-containing medium. The predominant cellular fatty acids (> 10%) in strain AGMB14963^T were C_14:0, C_16:0, and summed feature 3. Strain AGMB14963^T produced lactic acid and isobutyric acid as the major end products of glucose fermentation. Polar lipids consisted of one phospholipid and one phosphoaminolipid. According to the genomic, physiologic, and chemotaxonomic characteristics, strain AGMB14963^T represents a novel species of the genus Gallibacterium, for which the name Gallibacterium faecale sp. nov. is proposed. The type strain is AGMB14963^T (= KCTC 25487 ^T = NBRC 116419 ^T).

A novel phosphate-solubilizing and zinc-solubilizing actinobacterium strain YIM S08009^T was isolated from rhizosphere soil collected from Pinus yunnanensis in Wuliangshan National Nature Reserve, Pu'er City, Yunnan Province, southwest PR China. Cells of strain YIM S08009^T were Gram-stain-positive, non-motile, irregular rods to cocci, and formed yellow and white colonies on nutrient agar. Growth was observed at 10-40 °C (optimum 25-35 °C), pH 6.0-8.5 (optimum 7), and 0-4% (w/v) NaCl (optimum 1%). The cell wall peptidoglycan contained LL-diaminopimelic acid. The whole-cell sugars were mannose, ribose, glucose, and galactose. The predominant menaquinone was MK-8(H₄). Major polar lipids consisted of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol, unknown lipid, and 3 unknown phospholipids. The predominant fatty acids were iso-C_14:0, iso-C_15:0, and iso-C_16:0. The DNA G + C content was 72.6%. A phylogenetic analysis based on 16S rRNA gene sequences showed that strain YIM S08009^T belonged to genus Intrasporangium, and was most closely related to Intrasporangium flavum MUSC 78^T, with 99.0% 16S rRNA gene sequence similarity. Strain YIM S08009^T shared 90.1% orthologous average nucleotide identity (OrthoANI) and 39.8% digital DNA-DNA hybridization (dDDH) with I. flavum MUSC 78^T. The genome of strain YIM S08009^T contained phosphate-solubilizing genes (SenX3, RegX3, pstSCAB, ugpBAEC, phoA) and zinc-solubilizing genes (znuABC, zupT), and the strain had also demonstrated in vitro phosphorus and zinc solubilization. Based on the genotypic and phenotypic analyses, strain YIM S08009^T (= CGMCC 1.60168^T = NBRC 116604^T = KCTC 59021^T) represents a novel Intrasporangium species, for which the name Intrasporangium zincisolvens sp. nov. is proposed.

Endophytic fungi are non-pathogenic organisms that colonise healthy plant tissues asymptomatically. Endophytes derived from medicinal plants are sources for identifying natural products and bioactive compounds with potential uses for industry, medicine, agriculture, and related sectors. In the present study, ethyl acetate crude extracts of four endophytic fungal isolates (CALF1, CALF4, and CASF1) from the medicinal plant Plectranthus amboinicus showed potent antimicrobial activity against the test pathogenic bacteria Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, and Bacillus subtilis using disc diffusion assays. A colorimetric microdilution assay to detect the minimum inhibitory concentration (MIC) revealed that the extracellular extract (ECE) of CASF1 isolate had the lowest MIC values against the test pathogenic bacteria (0.19-6.25 mg/ml) compared to other CALF1 and CALF4. Cytotoxic activity of CASF1-ECE against the drug-resistant KB.CHR.8-5 cancer cell line tested by the MTT assay showed complete cell death at a concentration of 220 μg/mL and the half-maximum inhibitory concentration (IC₅₀) was determined to be 77.9 ± 09 μg/mL. GC-MS analysis showed hexadecanoic acid, 2-hydroxy-1-(hydroxymethyl) ethyl ester, as the dominant compound among the bioactive compounds identified in the EXE of CASF1 isolate, with the highest peak in the GC chromatogram, indicating its role in the antimicrobial and cytotoxic activity of CASF1. Molecular identification of CASF1 using 18S rRNA sequencing and BLAST analysis detected CASF1 as an isolate of Aspergillus versicolor with 100% sequence identity.