Folia microbiologica最新文献

Microbial entomopathogens that include fungi, bacteria, viruses, and nematodes have long been valued for their role in biological control of insect pests. However, recent research highlights their expanded applications beyond pest management. Entomopathogenic fungi such as Beauveria bassiana and Metarhizium spp. are increasingly recognized for their potential as biocontrol agents in integrated pest management systems. These fungi exhibit not only direct insecticidal effects but also secondary metabolites that contribute to plant disease suppression, thereby enhancing crop health and yield. Bacterial entomopathogen Bacillus thuringiensis, as the most widely used biopesticide, has also demonstrated potency not only against insects but also as systemic resistance inducer, thereby boosting plant immunity against pathogens. Moreover, entomopathogens are emerging as growth promoters and biostimulants, enhancing crop vigor through nutrient uptake and root development. This review consolidates current knowledge on the mechanisms of action of microbial entomopathogens against pests as well as current understanding on its other plant-beneficial traits. It also discusses their environmental impact and potential integration into sustainable agricultural practices. This comprehensive exploration underscores the transformative potential of microbial entomopathogens in shaping future strategies for holistic crop health management including pest management in agriculture.

Plant growth-promoting endophytes (PGPE) are microorganisms which reside in plant tissues and are beneficial to the host in plant growth promotion and pathogen resistance. They are the eco-friendly and sustainable alternative to chemical fertilizers and pesticides. This study aimed to analyze the plant growth-promoting properties of the five endophytic fungal strains from the medicinal plant Aegle marmelos Corr. and evaluate their effects on Oryza sativa plants. Firstly, endophytes were isolated from the different parts of A. marmelos and identified by ITS sequencing. Phosphate solubilization ability was checked in Pikovskaya's agar medium, IAA secretion was measured by the Salkowski colourimetric method, and ACC deaminase activity was checked by Penrose's method. Four endophytic fungal strains with promising PGP activities were inoculated into rice seeds to check their growth promotion in rice. The strain Purpureocillium lilacinum (AMR2) enhanced the seed vigour of rice seeds and demonstrated excellent root colonization ability. Periconia byssoides (AML2) and Medicopsis romeroi (AMS3) were the most effective plant growth-promoting agents, leading to both crop yield improvement and enhanced plant morphological growth due to their great ability to solubilize inorganic phosphate, ACC deaminase activity and production of IAA and Gibberellin A3 (GA3). These endophytic strains could serve as microbial inoculants to enhance crop production, offering an eco-friendly alternative.

Screening for tuberculosis infections (TBI) using the tuberculin skin test or interferon-gamma release assays (IGRA) is crucial in controlling the global TB burden. This study evaluates the performance of a new IGRA for the detection of T-cell responses against Mycobacterium tuberculosis. Blood samples from 34 adults with tuberculosis disease (TB) and from 30 children with TB, TBI or without TB were analyzed using the prototype Quan-T-Cell TB (EUROIMMUN). The pediatric samples were additionally measured using the established QuantiFERON-TB Gold Plus assay (Qiagen). Clinical performance and inter-assay concordance were analyzed. The prototype Quan-T-Cell TB yielded positivity rates of 88.2% and 100% in adults with TB and children with TBI, respectively, at a specificity of 93.8%. Comparison between the two IGRAs showed positive, negative and overall agreement rates of 100%, 93.8% and 96.3%, respectively, with a kappa score of 0.924 indicating almost perfect agreement. Our study shows promising results of the new prototype Quan-T-Cell TB, as reflected by high concordance with the final diagnosis in adults and children and performance comparable to that of the QuantiFERON IGRA. In individual cases, the data suggest that the prototype Quan-T-Cell TB may be even more consistent with TBI-related clinical findings. Unlike the QuantiFERON assay, the Quan-T-Cell TB has a predefined borderline range, which is advantageous as it may help to differentiate non-specific variation near the cut-off, and fewer sample tubes are required per analysis. The new Quan-T-Cell TB may therefore be a good alternative to the established QuantiFERON IGRA for TBI screening. Further assay optimization is underway, including evaluation studies based on larger patient and control cohorts.

Despite Pakistan's rich reptilian diversity, wild lizards have largely been unexplored for vector-borne parasites. This study reports the prevalence and phylogenetic assessment of Hepatozoon ophisauri and Toxoplasma gondii DNA in the blood samples of 101 wild lizards from Khyber Pakhtunkhwa, Pakistan, captured at altitudes of 1200 to 2250 m above sea level between March 2022 and June 2023. PCR-based molecular analysis identified H. ophisauri DNA in three (3%) lizards of all Laudakia tuberculata. Additionally, 45 (44.5%) lizards tested positive for T. gondii DNA, including L. agrorensis, L. pakistanica, L. tuberculata, and Abblepharus pannonicus. Sequence analysis and BLAST confirmed the presence of H. ophisauri and T. gondii. Phylogenetic analysis showed genetic diversity among the H. ophisauri and T. gondii nucleotide sequences, clustering with reference sequences from reptiles, birds, and ticks. Toxoplasma gondii prevalence varied among species, with the highest rates in L. agrorensis and A. pannonicus (67%), followed by L. pakistanica (45%) and L. tuberculata (43%). This study is the first from Pakistan to report high T. gondii prevalence and low H. ophisauri prevalence in wild lizards. Similar and larger-scale studies in unexplored regions of Pakistan are needed to enhance understanding of these pathogens' genetic diversity and host-parasite interactions.

The advent of CRISPR/Cas technology has revolutionized genome editing, offering simplicity, precision, and cost-effectiveness. While its application in biological control fungi has been limited, including the cosmopolitan fungus Metarhizium anisopliae, recent advancements show promise. However, integrating cas9 and selection-marker genes into fungal genomes poses challenges, including reduced efficiency, toxicity, and off-target effects. Besides, marker-free genetic engineering through a CRISPR recyclable system presents a viable solution, enabling efficient mutant generation without compromising fitness and virulence. This study pioneers the construction of marker-free strains of M. anisopliae using a CRISPR/Cas9 recyclable system. Precise deletion of albA and ku70, alongside gfp cassette insertion, confirms the system efficiency. This innovative approach holds significant potential for facilitating in-depth molecular studies, understanding their ecological roles in agricultural systems, and enhancing biocontrol efficacy against insect pests through genetic improvement.

Lipases are among the most significant biocatalysts that constitute the third most important group of enzymes due to their vast range of applications. The present research represents the first attempt to optimize the growth medium constituents to increase the production of recombinant lipase in Pseudomonas aeruginosa SDK-6. One factor at a time (OFAT) revealed castor oil, yeast extract, and ammonium nitrate as the most significant medium components affecting the recombinant lipase production. Further optimization via response surface methodology (RSM) resulted in lipase production of 115.50 U/mL with 0.5% (v/v) castor oil, 0.2% (w/v) yeast extract, and 0.1% (w/v) ammonium nitrate at pH 7. Statistical validation of the observed value via ANOVA revealed an F value of 117.02 at p < 0.01, with an R² of 0.9909. An overall 3.58-fold lipase production was achieved after optimization via OFAT and RSM. The purified lipase exhibited a specific activity of 102.73 U/mg, and the molecular mass was deduced to ~ 19.5 kDa via sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The optimum temperature and pH for the recombinant lipase activity were 40 °C and 10, respectively. The enzyme retained most of its initial activity up to 32 h when incubated at an elevated temperature of 40 °C. The purified enzyme also exhibited stability over alkaline pH, with remarkable stability at pH 12. The enzyme activity was enhanced in the presence of CaCl₂, MgCl₂, FeCl₂, NaCl, methanol, dichloromethane, and Triton X-100. The enzyme also retained most of its initial activity in the presence of all other screened organic solvents.

The healthcare sector is currently concerned about infections caused by Porphyromonas gingivalis biofilms due to their high frequency and incidence, particularly in patients with implanted medical devices. This study investigated biofilm formation and biofilm-related gene expression in P. gingivalis on titanium-copper discs and polycarbonate discs. P. gingivalis highly expressed biofilm-related genes were examined using quantitative real-time PCR during biofilm formation on the Ti-Cu surface. SEM analysis revealed various cellular components around the aggregated cells at various stages of biofilm formation. The Ti-Cu surface was colonized by P. gingivalis, as evidenced by biofilm formation levels that varied from ~ 10³-10⁴ CFU/cm² after 2 days of incubation to ~ 10⁵-10⁷ CFU/cm² after 7 days. Real-time expression analysis showed a significant increase in the expression of signaling molecules on Ti-Cu discs. Furthermore, genes linked to virulence (rgpA, rgpB, and Kgp, fimC, PorK, and PorP) and adhesion (mfa1, fimD, fimA, RpoN, rgpA, rgpBiKgp) demonstrate transcriptional alterations in signaling pathways impacting P. gingivalis biofilm on Ti-Cu surfaces. Scanning electron microscopy (SEM) and confocal microscopy correlated the results of the structural analysis with the expression from the qPCR data. This study adds significant value by advancing the understanding of biofilm formation on Ti-Cu implants.

Mangrove forests support robust microorganisms due to their changing temperature and salinity conditions. Tropical yeasts isolated from such habitats have the potential to produce clinically significant enzymes like L-asparaginase. L-asparaginase converts L-asparagine to L-aspartate and ammonia. In this study, 14 tropical yeasts were isolated from mangrove sediments collected from Madkai, Goa, India. From these, on screening with two different indicator dyes phenol red and bromothymol blue, five isolates were positive for L-asparaginase enzyme as indicated by rapid plate assay technique. Isolate having highest enzyme activity was identified as belonging to genus Cyberlindnera. The study of effect of physical parameters on enzyme production revealed optimal incubation time of 48 h, pH of medium 7.0 and incubation temperature of 28 °C. Evaluation of carbon and nitrogen sources indicated L-asparagine as sole nitrogen source and glucose as carbon source achieved maximum enzyme production. L-Asparaginase activity of isolate GULAMMS8 under optimal medium composition and parameter conditions that are glucose as carbon source with L-asparagine as sole nitrogen source and pH of 7.0, an incubation temperature of 28 °C showed a two-fold increase, while the incubation period was halved. This work is a primary study on L-asparaginase producing tropical mangrove yeast belonging to genus Cyberlindnera aiming to understand the influence of physical factors and nutrient sources on enzyme production.

Dahi, a traditional yet underexplored fermented milk product from Pakistan, harbors diverse lactic acid bacteria (LAB) that have potential as probiotics. These bacteria could be used for therapeutic purposes, beneficial modulation of gut microbiota, and in the formulation of functional foods and feeds. This study aimed to isolate and characterize probiotic LAB from dahi, assess their survival in simulated gastrointestinal conditions, and evaluate their safety and probiotic potential, both phenotypically and genotypically. A total of 143 isolates from 37 samples were evaluated for probiotic traits, including acid and bile tolerance, antibacterial activity, cholesterol-lowering capacity, and antioxidant activity. The strains were also tested for antibiotic sensitivity and safety through in vitro tests and genomic analysis. A multi-strain probiotic consortium was developed and tested for enhanced functionality. Out of 143 isolates, 62 LAB strains were identified. These strains demonstrated significant survival under acidic (pH 2) and bile conditions. Antibacterial activity against pathogens ranged from 51 to 88%. The strains exhibited high cholesterol removal (up to 98%) and antioxidant activity (up to 76%). Genomic analysis revealed the presence of key probiotic-related genes, including those for acid resistance, bile salt hydrolase, and adhesion. All strains were sensitive to EFSA-recommended antibiotics and exhibited no hemolytic or DNase activity, confirming their safety. The multi-strain consortium showed superior probiotic potential and survival in simulated gastrointestinal conditions. LAB strains isolated from dahi possess strong probiotic potential, confirmed through in vitro and genomic safety assessments. The multi-strain consortium holds promise for applications.

In recent decades, there has been a growing interest in harnessing plant growth-promoting rhizobacteria (PGPR) as a possible mechanism to mitigate the environmental impact of conventional agricultural practices and promote sustainable agricultural production. This study investigated the transferability of promising PGPR research from maize to another Poaceae cereal crop, wheat. This multi-seasonal study evaluated the wheat grain yield effect of Lysinibacillus sphaericus (T19), Paenibacillus alvei (T29) when applied i. individually, ii. as a consortium with Bacillus safensis (S7), and iii. at a 75% reduced fertilizer rate. Whole genome sequencing allowed annotation of genes linked to plant growth promotion, providing potential genomic explanations for the observed in-field findings. Application of the consortium compared to a commercial PGPR showed significantly increased wheat yield by 30.71%, and 25.03%, respectively, in season one, and 63.92% and 58.45%, respectively, under reduced fertilizer rates in season two. Individual application of T19 and T29 showed varying results, with T19 increasing wheat yield by 9.33% and 16.22% during seasons three and four but a substantial reduction (33.39%) during season five. T29 exhibited yield increases during season three (9.31%) and five (5.61%) but led to a significant reduction (21.15%) in season four. Genomic analysis unveiled a spectrum of plant growth-promoting genes including those associated with ammonification, phosphate solubilization, ethylene, siderophore, catalase, and superoxide dismutase production. These findings offer valuable insights into the mechanisms behind observed field results, with potential implications for advancing sustainable agriculture and crop productivity in evolving agricultural landscapes.