Journal of Basic Microbiology最新文献

Research on nematode management globally highlights the use of nematicidal biomolecules and biocontrol agents. However, the availability of biomolecules to manage plant-parasitic nematodes remains limited. The discovery of microbial biomolecules offers new opportunities in this field, though they are underexplored for suppressing nematodes. This study focused on identifying biomolecules from Bacillus licheniformis (MW301654) to manage Meloidogyne incognita, a root-knot nematode infecting banana. In silico protein-ligand interactions revealed that, Nicotinamide mononucleotide, produced during the ditrophic interaction of B. licheniformis (MW301654) with Fusarium oxysporum f. sp. cubense was effective against M. incognita protein targets including cytochrome C oxidase subunit 1, calreticulin, neuropeptide G-protein coupled receptor, chorismate mutase 1, venom allergen-like proteins and β-1,4-endoglucanase than the commercially used nematicides carbofuran 3G and fluensulfone. In vitro bioassays further validated nicotinamide mononucleotide nematicidal activity. At concentrations of 93, 76, and 69 ppm, nicotinamide mononucleotide caused 50% mortality of second-stage juveniles after 24, 48, and 72 h, respectively, while 213, 132, and 101 ppm resulted in 95% mortality. Egg hatching was also significantly reduced, with only 1% hatching at 150 ppm. The study emphasized the potential of Nicotinamide mononucleotide as a novel biopesticide for the management of M. incognita infection in banana.

LysM effectors are suppressors of chitin-triggered plant immunity in biotrophic and hemibiotrophic fungi. In necrotrophic fungi, LysM effectors might induce a mechanism to suppress host immunity during the short asymptomatic phase they establish before these fungi activate plant defenses and induce host cell death leading to necrosis. Here, we characterize a secreted LysM protein from a major necrotrophic fungus, Botrytis cinerea, called BcLysM1. Transcriptional induction of BcLysM1 gene was observed in multicellular appressoria, called infection cushions, in unicellular appressoria and in the early phase of infection on bean leaves. We confirmed that BcLysM1 protein binds chitin in the fungus cell wall and protects hyphae against degradation by external chitinases. This effector is also able to suppress the chitin-induced ROS burst in Arabidopsis thaliana, suggesting sequestration of chitooligosaccharides in apoplast during infection. Moreover, contribution of BcLysM1 in infection initiation and in adhesion to bean leaf surfaces were demonstrated. Our data show for the first time that a LysM effector can play a dual role in mycelial adhesion and suppression of chitin-triggered host immunity, both of which occur during the early asymptomatic phase of infection by necrotrophic fungi.

Plant growth-promoting activities using biological, chemical, and organic fertilizers are well-documented for pest insects, their impacts on predators are less commonly studied. This research investigates whether bell pepper plants treated with plant growth-promoting rhizobacteria (PGPRs), arbuscular mycorrhizal fungi (AMF), vermicompost (30%), and zinc sulfate either separately or in selected combinations affect the nutrient indices and population growth traits of the ladybug predator, Hippodamia variegata (Goeze), when fed on aphids, Myzus persicae (Sulzer). Bell pepper plants were individually treated with two PGPRs (Bacillus subtilis and Pseudomonas fluorescens), one AMF (Glomus intraradices), soil amended with 30% vermicompost (v/v), and foliar application of zinc sulfate under greenhouse conditions. Combined treatments of AMF × B. subtilis and AMF × P. fluorescens were also tested. Nutritional indices and population growth parameters of predator were reared on the treated plants infested with aphids. Results showed that the efficiency of conversion of ingested food (ECI) in predator larvae was highest on B. subtilis-treated aphids and lowest on vermicompost-treated aphids. The relative growth rate (RGR) of predator was the highest on zinc sulfate-treated aphids and lowest on vermicompost-treated aphids. Predators fed on vermicompost-treated aphids had the lowest net reproductive rate (R₀) and intrinsic rate of increase (r), while R₀ was highest for predators fed on B. subtilis-treated aphids and r was highest on P. fluorescens- and B. subtilis-treated aphids. These findings suggest that zinc sulfate and biological fertilizers involving PGPRs can enhance the ecological fitness of predators and could be effective in biocontrol-based integrated pest management of aphids.

Bisphenol A (BPA), an endocrine disruptor is used in manufacturing of polycarbonate plastics for food-drink packaging. In the present study, optimized set of conditions to degrade commercial grade BPA has been used and applied in degrading shredded leached low-density polyethylene (LDPE) residues and its leachate (198 µg/L BPA) using white rot fungus Hypocrea lixii. One-at-a-time method showed maximum BPA degradation of 98.73 ± 0.02% with 190.1 ± 0.2 U/L laccase and 1913.2 ± 0.3 U/L lignin peroxidase in glucose-yeast extract-malt extract-peptone (GYMP) medium supplemented with 5% sawdust, mediators-CuSO₄ (0.2 mM), veratryl alcohol (0.1 mM) and Tween 80 (0.1 mM). Three sets were prepared by dissolving these optimized nutritional components in leachates-A (only leachate), B (leached LDPE residues in leachate) and C (leached LDPE residues, sawdust in leachate). All sets showed 100% degradation in 5 days. Cracks and holes in degraded LDPE pieces was confirmed by SEM analysis and changes in functional groups by FTIR. Toxicity assay of treated leachate on soil microfauna revealed the elimination of BPA as it supported sufficient microbial growth of soil bacteria. Thus, the present process provides a sustainable solution for the management of LDPE with the possibility of using treated leachate for irrigation.

Root rot caused by Macrophomina phaseolina, a common soil-borne disease in black gram, is managed with chemical fungicides, leading to toxicity and degradation of beneficial soil microbes. Existing bioagents, like talc formulation, cause leaching, clogging, and reduced productivity. The development of liquid bio-formulation via drip irrigation is crucial to mitigate biotic stress and maximize yield. This study aims to investigate the efficacy and survivability of liquid formulation of Trichoderma asperellum against root rot and its growth promotion. The results showed that Tv1 effectively inhibited M. phaseolina (66.67%), under in vitro condition. The vigor index of 4025.00 and the spore load of 1 × 10⁸ cfu/mL were recorded from plant growth promotion and spermosphere study @ 5 mL/kg of seeds with formulation. The study found that combined application of seed treatment @ 5 mL/kg of seed and soil application @ 10 mL/L of water significantly reduced disease incidence (9.1%) against control (74.3%), with increased biomass index. There are 32 mVOCs profiled during the tritrophic interaction in roots of black gram and they were up or downregulated, viz., mollugin, pentadecanoic acid, cyclopropaneoctanoic acid, 2-octyl-, methyl ester, rhodopin, dodecanoic acid, 1,2,3-propanetriyl ester by involved in defense mechanism and biosynthetic pathways like jasmonic acid, glyconeogenic and act as acyl-CoA: acyltransferase 2 inhibitor. The results of this study confirmed that liquid formulation performs better in growth promotion, survivability on seed surface, and managing root rot of black gram compared talc-based formulation.

The production of cellulolytic enzymes in Aspergillus aculeatus is regulated at transcriptional levels in response to inducers and various physiological signals. In this study, we identified that a component of the septation initiation network complex, SepL, a putative protein kinase, was involved in the expression of carbohydrate-active enzyme (CAZyme) encoding genes. The deletion of sepL (ΔsepL) in A. aculeatus resulted in a deficiency in both septation and conidiation and sensitivity to Congo red. These phenotypes of ΔsepL are conserved in Aspergillus. In addition to the conserved function of SepL in Aspergillus, we found that SepL in A. aculeatus was necessary for the inducible expression of the CAZyme genes in response to cellobiose, whereas the inducible expression of these genes in response to 1,4-β-mannobiose was significantly reduced but not abolished. Combining the results of the present functional analysis of SepL with previous evidence that the expression of the CAZyme genes, which is responsive to both cellobiose and 1,4-β-mannobiose, is regulated by a transcription factor ManR in A. aculeatus, indicates that SepL in A. aculeatus is involved in the selective expression of the cellobiose-responsive CAZyme genes under the control of ManR.

Cover illustration:

Growth disc of an anamorphous fungus Trichospsoron sp. isolated from a rotten zucchini marketed. This phytopathogenic-pectinolytic fungus was tested against several strains of plant growth-promoting rhizobacteria to test its sensitivity to assess the capacity of five highly effective PGPR-Bacillus strains, which were obtained from the rhizosphere of date palms.

(Photo: Merdia Bestami, Department of Natural and Life Sciences, Faculty of Sciences and Technology, University of Amine Elokkal ElHadj Moussa Eg. Akhamoukh, Tamanrasset, Algeria)

We have earlier reported novel anti-leishmanial molecules, veratramine and hupehenine, targeting dephospho-coenzyme A kinase of the parasite. In our current investigation, we assessed the efficacy of these two steroidal alkaloids, veratramine and hupehenine, in combating the parasite. Contrary to expectations, our study did not detect the typical signs of apoptosis such as mitochondrial membrane potential loss and phosphatidylserine externalization. Instead, we observed a notable increase in acidic organelle formation, suggesting a pro-survival response in promastigotes. Through diverse flow cytometric analyses and imaging methods, we conclude that the parasitic death induced by these natural compounds does not follow the apoptosis pathway but likely involves autophagy. This discovery marks the first instance of autophagy-mediated cell death in Leishmania donovani triggered by veratramine and hupehenine.