Current Microbiology最新文献

In order to identify the pathogen responsible for Hedera nepalensis leaf blight and investigate effective biocontrol strategies, samples were collected from 10 significantly infected areas at Southwest Forestry University; four to six infected leaves were gathered from each area, followed by the isolation and purification of strains from the infected plant leaves using tissue isolation and hyphae-purification techniques. We conducted an examination of the biological characteristics and compared the inhibitory effects of different concentrations of Phomopsis sp. (50%, 25%, 16.7%, 12.5%, and 10%) with 20 µg/mL of synthetic fungicides (Mancozeb, Carbendazim, Polyoxin, and Hymexazol) on the pathogen, while also assessing the control efficacy of Phomopsis sp. against the pathogen in the greenhouse. The internal transcribed spacer (ITS) region, β-tubulin (TUB), and translation elongation factor 1-alpha (TEF) analysis revealed that the highly virulent strain causing H. nepalensis leaf blight was Apiospora intestini. Additionally, it was found that 25% Phomopsis sp. significantly inhibited Apiospora intestini when compared to synthetic fungicides, and Phomopsis sp. supernatant possesses both protective and curative effects against the plant diseases caused by Apiospora intestini. The results of this study serve as a reference for the prevention and treatment of H. nepalensis leaf blight.

Interactions between microbial communities and the host can modulate mosquito biology, including vector competence. Therefore, future vector biocontrol measures will utilize these interactions and require extensive monitoring of the mosquito microbiome. Metabarcoding strategies will be useful for conducting vector monitoring on a large scale. We used 16S and 18S rRNA gene metabarcoding through iSeq100 sequencing to characterize the microbiome and eukaryome of Aedes albopictus (Skuse 1894) and Culex pipiens (Linnaeus 1758), two globally important vectors present in South Korea. Mosquitoes were collected from an urban and a semi-urban location in South Korea. Bacterial alpha and beta diversities varied by population. Pseudomonadota dominated the microbiomes of both species. The microbiome composition varied by population and was dominated by different taxa. At the genus level, Wolbachia sp. was the most enriched genus in Cx. pipiens, followed by Aeromonas sp. In Ae. Albopictus, the most abundant group was Enterococcus sp. The gregarine parasite Ascogregarina taiwanensis was highly prevalent in Ae. Albopictus and its absence was marked by the presence of seven bacterial taxa. To our knowledge, this is the first characterization of the microbiome of Ae. albopictus and Cx. pipiens in these regions of South Korea and contributes to the current information on the microbiome of mosquito species, which can be used in further studies to assess pathogen-microbiome and microbiome-microbiome interactions.

Endophytes are bacteria that inhabit host plants for most of their life cycle without causing harm. In the study, 15 endophytic bacteria were isolated from 30 forage Sorghum plants and assessed for various plant growth-promoting (PGP) traits, such as phosphate solubilization, 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase activity, ammonia production, siderophore production, gibberellic acid production, Indole-3-acetic acid (IAA) production, and zinc solubilization. One isolate, JJG_Zn, demonstrated multiple PGP activities and was identified as Enterobacter sp. through 16S rRNA sequencing. Considering the concept of 'One health,' a comprehensive biosafety analysis for any plant growth-promoting bacteria (PGP bacteria) is essential, thus, Enterobacter sp. (JJG_Zn), along with two other standard cultures, Burkholderia seminalis and Stenotrophomonas maltophilia, were evaluated for biosafety tests-including sheep blood agar assay, E.coli sensitivity assay, and pathogenicity tests on albino mice. The results indicated that all three PGP bacteria were potentially innocuous and compatible with each other. Furthermore, the field experiments were conducted at Punjab Agricultural University, Regional Research Station, Bathinda, and School of Organic Farming, IFS, Punjab Agricultural University, Ludhiana during Kharif 2022 employing a randomized complete block design (RCBD) with nine treatment combinations. The treatments included liquid bacterial inoculants (LBIs) of Stenotrophomonas maltophilia, Burkholderia seminalis, and Enterobacter sp. (JJG_Zn) applied in combination with 100% and 75% of the recommended dose of fertilizer (RDF), with each treatment replicated thrice. The treatment T₉ (75% RDF + dual inoculation with B. seminalis and S. maltophilia) resulted in the highest productivity, showing a 10.23% increase in pooled green fodder yield (GFY) compared to the control. The treatment T₈ (75% RDF + Enterobacter sp. (JJG_Zn)) showed a 5.14% increase in productivity over the control. Thus, liquid bacterial inoculants (LBIs) present a promising approach to enhance the productivity of forage Sorghum.

In the present study, the taxonomic position of Salinisphaera halophila (NZ_AYKF00000000) and Salinisphaera orenii (NZ_AYKH00000000) was re-evaluated. In addition, their metabolic potentials and mechanisms for mitigating stress conditions were determined. Comparisons of 16S rRNA gene sequences, analysis of the phylogenetic tree, phylogenomic tree, average nucleotide identity (ANI), and digital DNA-DNA hybridization (dDDH) values were conducted. The 16S rRNA gene sequence similarity between Salinisphaera halophila YIM 95161^T and Salinisphaera orenii MK-B5^T was 100%. In phylogenetic and phylogenomic trees, Salinisphaera halophila YIM 95161^T and Salinisphaera orenii MK-B5^Tclustered together. Both species encode genes for glycolysis, citrate cycle, pentose phosphate pathway, Entner-Doudoroff pathway, nitrate assimilation, and assimilatory sulfate reduction. They employ salt-in and salt-out strategies to mitigate salt stress. The ANI and dDDH values between Salinisphaera halophila YIM 95161^Tand Salinisphaera orenii MK-B5^Twere 96.6 and 72.1%, respectively, above the cut-off (95-96% for ANI and 70% for dDDH) for species delineation. Based on the above results, we propose to reclassify Salinisphaera halophila Zhang et al. 2012 as a later heterotypic synonym of Salinisphaera orenii Park et al. 2012.

Traditional Turkish fermented foods like boza, pickles, and tarhana are recognized for their nutritional and health benefits, yet the probiotic potential of lactic acid bacteria (LAB) strains isolated from them remains underexplored. Sixty-six LAB strains were isolated from fermented foods using bacterial morphology, Gram staining, and catalase activity. The isolates were differentiated at strain level by RAPD-PCR (Random Amplification of Polymorphic DNA-Polymerase Chain Reaction) and twenty-five strains were selected for further evaluation of acid and bile salt tolerance. Among these, ten strains exhibited high tolerance and were subsequently assessed for adhesion to Caco-2 colorectal carcinoma cells, antimicrobial activity, exopolysaccharide (EPS) production, lysozyme resistance, and hemolytic activity. Using k-means clustering, three strains: Lactiplantibacillus plantarum ES-3, Pediococcus pentosaceus N-1, and Enterococcus faecium N-2 demonstrated superior probiotic characteristics, including significant acid (100% survival at pH3.0) and 0.3% bile salt tolerance (57%, 64%, 67%), strong adhesion to intestinal cells (65%, 88%, 91%), high lysozyme resistance (88%, 88%, 77%), and produced high amounts of EPS. These strains show promising potential as probiotics and warrant further investigation to confirm their functional properties and potential applications.

In the present study, the taxonomic position of Salisediminibacterium haloalkalitolerans was evaluated by determining the 16S rRNA gene sequence similarity, genome relatedness, and phylogenetic analyses. The 16S rRNA gene sequences extracted from the genomes of Salisediminibacterium haloalkalitolerans 10nlg^T and Salisediminibacterium halotolerans DSM 26530^T showed 100% similarity, supporting their classification as the same species. The average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values between S. haloalkalitolerans and S. halotolerans were 97.7 and 80.2%, respectively, above the cutoff value (95-96% ANI; 70% dDDH) for species delineation. S. haloalkalitolerans and S. halotolerans should be classified as the same species because the 16S rRNA gene phylogeny and phylogenomic tree (based on 71 bacterial single-copy genes) showed no genetic divergence between them. Based on the above results and the rule of priority in nomenclature, we propose to reclassify Salisediminibacterium haloalkalitolerans Sultanpuram et al. 2015 as a later heterotypic synonym of Salisediminibacterium halotolerans Jiang et al. 2012.

Xanthomonas citri pv. malvacearum (Xcm) associated with bacterial blight disease is a significant and widespread pathogen affecting cotton worldwide. The excessive use of harmful chemicals to control plant pathogens has exerted a negative impact on environmental safety. Thymol is a monoterpene phenol present in the essential oils of plants belonging to Lamiaceae family. In this study the antimicrobial activity of thymol was evaluated against Xcm. The minimum inhibitory concentration (MIC) and 99.9% bactericidal concentration (MBC) of thymol against Xcm were 2 and 4 mg/mL, respectively. The effect of MIC and MBC of thymol against Xcm was assessed on the Luria-Bertani medium. The effect of thymol on intercellular ATP levels, membrane potential, and motility in Xcm was assessed using fluorescence spectrometry for membrane potential and firefly luciferase-based assay for ATP levels. Thymol ruptured the cellular membrane of Xcm, resulting in decreased intracellular ATP concentrations, intracellular leakage of genetic material, and changes in membrane potential. Scanning electron microscopy images supported the impact of thymol on the cell membrane of Xcm. Moreover, thymol inhibited the swimming motility and biofilm formation of Xcm at concentrations equal to or above the MIC and MBC. In contrast, sub-MIC concentrations of thymol had little to no impact on the virulence of Xcm. In conclusion, thymol demonstrated the potential as a strong bactericidal compound against Xcm.

Pigeonpea (Cajanus cajan L.) plants exhibiting symptoms of yellow mosaic disease (YMD) were collected in winter 2023 from multiple agricultural fields of Kanpur, Sehore, and Madhubani, representing three different agro-ecological zones in India. The recorded disease incidence ranged from 3 to 5%, 1 to 4%, and 12 to 20% in these zones, respectively. This study aimed to identify and characterize the causal agent, suspected to be a begomovirus, an emerging plant pathogen of pigeonpea causing YMD. Total DNA was extracted from 28 YMD-affected leaf samples and subjected to rolling circle amplification for PCR-based virus detection. Of all the tested samples, one tested positive for mungbean yellow mosaic virus (MYMV), while the remaining tested positive for mungbean yellow mosaic India virus (MYMIV). Subsequently, PCR-based amplification and sequencing of the full-length DNA-A and DNA-B components were conducted. BLASTn analysis revealed that the assembled sequences of the DNA-A and DNA-B components had the highest nucleotide identity with MYMIV (DNA-A: 97-99%, DNA-B: 95-97%) and MYMV (DNA-A: 99%, DNA-B: 98%). Phylogenetic analysis supported these findings. Additionally, the DNA-A and DNA-B components obtained from each sample were found to be cognate, with over 92% similarity in their common region. Thus, the cognate DNA components constituted the isolates of MYMIV and MYMV identified from pigeonpea. The identified isolates exhibited the typical genome organization of an Old World bipartite begomovirus, with no recombination events detected. This study reports, for the first time, the complete annotated genomes of MYMIV from Sehore and Madhubani, as well as MYMIV and MYMV from Kanpur, infecting pigeonpea.

Infections caused by antibiotic-resistant bacteria (ARB) result in an estimated 1.27 million human deaths annually worldwide. Surface waters are impacted by anthropogenic factors, which contribute to the emergence and spread of ARB in the aquatic environment. While research on antibiotic resistance in surface waters has increased recently in developing nations, including Bangladesh, especially in aquaculture, such studies are still limited in Bangladesh compared to developed nations. In this study, bacteria strains isolated from three rivers and two lakes in Khulna city, Bangladesh were characterized for their antibiotic resistance using disk diffusion method. Of the 106 bacterial isolates from 180 surface water samples, the majority exhibited resistance to Ciprofloxacin (75.0-87.5%) and Ceftriaxone (65.6-78.1%), while resistance to Ampicillin was comparatively lower (9.4-18.8%). Notably, the prevalence of ARB was observed to be higher during the wet seasons compared to the dry seasons. The 16S rRNA gene analysis showed that Shigella flexneri was the most dominant (17.9%) bacterium among the ARB cultured from surface waters, followed by Escherichia fergusonii (12.5%), Proteus mirabilis (10.7%), and Enterobacter quasiroggenkampii (8.9%). At the genus level, Enterobacter (23.5%), Shigella (20.6%), and Escherichia spp. (14.7%) were the most abundant among the ARB in both river and lake samples. The findings of this study highlight the prevalence of antimicrobial resistance in surface water sources and suggest the need for enhanced monitoring and improved disposal practices to mitigate potential public health risks.

Groundnut fodder was utilized as a bioresource for the production of cellulases through solid state fermentation (SSF). Aspergillus unguis was initially grown on modified groundnut fodder for cellulase production and the fodder was hydrolyzed by the crude cellulase extract into fermentable hydrolyzate. The highest titer of Filter paperase (FPase), Carboxymethyl cellulase (CMCase), β-glucosidase, and protein content were found to be 11.4, 11.5, 33.3 U/g, and 136.6 mg/g of substrate, respectively. Treatment of groundnut fodder with dilute acid and supplementation of mineral salts, and yeast extract (5% w/v) enhanced cellulase production. The hydrolysis of modified groundnut fodder treated with Tween-80 using the crude cellulase extract resulted in increased production of reducing sugars (40%) at 50 °C compared with control. In conclusion, the addition of Tween-80 at pH 4.8 increased a twofold increase in the yield of reducing sugar.