In vitro antagonism of Trichoderma species against six fungal plant pathogens [Biological disease control]

Methomyl is a broad-spectrum oxime carbamate commonly used to control arthropods, nematodes, flies, and crop pests. However, extensive use of this pesticide in agricultural practices has led to environmental toxicity and human health issues. Oxidation, incineration, adsorption, and microbial degradation methods have been developed to remove insecticidal residues from soil/water environments. Compared with physicochemical methods, biodegradation is considered to be a cost-effective and ecofriendly approach to the removal of pesticide residues. Therefore, micro-organisms have become a key component of the degradation and detoxification of methomyl through catabolic pathways and genetic determinants. Several species of methomyl-degrading bacteria have been isolated and characterized, including Paracoccus, Pseudomonas, Aminobacter, Flavobacterium, Alcaligenes, Bacillus, Serratia, Novosphingobium, and Trametes. The degradation pathways of methomyl and the fate of several metabolites have been investigated. Further in-depth studies based on molecular biology and genetics are needed to elaborate their role in the evolution of novel catabolic pathways and the microbial degradation of methomyl. In this review, we highlight the mechanism of microbial degradation of methomyl along with metabolic pathways and genes/enzymes of different genera.

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Current Approaches to and Future Perspectives on Methomyl Degradation in Contaminated Soil/Water Environments.

The present study compares the demands for P of the initial nodule formation, and of the later growth and functioning of the nodulated root system in two inoculated lines of common bean (Coco blanc and BAT477). After germination and inoculation, seedlings were divided into two lots. One lot was grown under constant P supply, either 15 (low) or 250 (high) µM P, corresponding to provision of 120 and 2000 µmol P, respectively. In the second, seedlings were cultivated on the same medium supplied with 15 µM P for 24 days after germination, and then with 60 or 250 µM (total provision of P: respectively, 390 and 1530 µmol). Nodule number and biomass were significantly diminished by the low P (120 µmol) treatment, as compared with the other treatments. However, the intrinsic characteristics of the nodules (individual biomass and size, P concentration and efficiency of N fixation) did not depend on P availability. Although the bean line BAT477 was distinguished from the Coco blanc line through higher nodule number, size, biomass, and nitrogen fixation, both lines displayed analogous responses to P availability.

Effect of P on nodule formation and N fixation in bean. Agron Sustain Dev

Tricholoma matsutake has been popular as food and biopharmaceutical materials in Asian countries for its various pharmacological activities. The present study aims to analyze the antifatigue effects on enhancing exercise performance of Tricholoma matsutake fruit body (ABM) and liquid cultured mycelia (TM) in mouse model. Two-week Tricholoma matsutake treatment significantly enhances the exercise performance in weight-loaded swimming, rotating rod, and forced running test. In TM- and ABM-treated mice, some factors were observed at 60 min after swimming compared with nontreated mice, such as the increased levels of adenosine triphosphate (ATP), antioxidative enzymes, and glycogen and the reduced levels of malondialdehyde and reactive oxygen species in muscle, liver, and/or serum. Further data obtained from western blot show that CM and ABM have strongly enhanced the activation of 5′-AMP-activated protein kinase (AMPK), and the expressions of peroxisome proliferator have activated receptor γ coactivator-1α (PGC-1α) and phosphofructokinase-1 (PFK-1) in liver. Our data suggest that both Tricholoma matsutake fruit body and liquid cultured mycelia possess antifatigue effects related to AMPK-linked antioxidative pathway. The information uncovered in our study may serve as a valuable resource for further identification and provide experimental evidence for clinical trials of Tricholoma matsutake as an effective agent against fatigue related diseases.

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Antifatigue Activity of Liquid Cultured Tricholoma matsutake Mycelium Partially via Regulation of Antioxidant Pathway in Mouse

Realizing the severity of fungicidal toxicity to legumes and importance of fungicide tolerant rhizobia in legume production, kitazin tolerant (2400 μg mL−1) strain RP1 was recovered from pea nodules and was identified as Rhizobium leguminosarum (accession no. KY940047). R. leguminosarum produced indole acetic acid (80.5 ± 2.5 mL−1), siderophores: salicylic acid (54 ± 7.3 μg mL−1) and 2,3-dihydoxybenzoic acid (31.9 ± 2.7 μg mL−1), α-ketobutyrate (51 ± 3.2 per mg per protein per hour), solubilized insoluble phosphate (29.5 ± 1.8 μg mL−1) and secreted 29.5 + 2.6 μg mL−1 exopolysaccharides, which, however, decreased consistently with gradually increasing kitazin concentrations. Beyond the tolerance level, kitazin caused structural damage and altered membrane integrity of RP1, as revealed under scanning (SEM) and confocal (CLSM) electron microscopy. Phytotoxicity of kitazin to peas was obvious under both in vitro and in vivo conditions. A significant reduction of 23, 68, 57 and 50% in germination, seedling vigor index, plumule length and radicle length was found at 2× kitazin compared to the control. Cellular damage and cytotoxicity induced by kitazin in membrane altered root cells was detected with acridine orange/propidium iodide (AO/PI) and Evans blue dye. A maximum increase of 1.72, 5.2, 9.3 and 1.72, 5.2, 9.3-fold in red and blue fluorescence was quantified at 1×, 2×, and 3× doses of kitazin, respectively. In contrast, application of R. leguminosarum RP1 alleviated toxicity and enhanced the length of plant organs, dry biomass, symbiotic attributes, photosynthetic pigments, nutrient uptake and grain features of peas comparatively uninoculated and fungicide-treated plants. Additionally, strain RP1 expressively reduced the antioxidant enzymes peroxidase, ascorbate peroxidase, guaiacol peroxidase, catalase and malondialdehyde contents by 10, 2.2, 11, 20 and 4% compared to stressed plants raised at 192 μg kg−1 soil. Moreover, a decline of 19, 21 and 20% in proline content extracted from roots, shoots and grains, respectively was recorded for R. leguminosarum inoculated pea plants grown with 96 μg kg−1 kitazin. Also, the SEM and CLSM of roots revealed the bacterial colonization. In conclusion, R. leguminosarum tolerated a higher level of kitazin, secreted plant growth promoting (PGP) bioactive molecules even under fungicide stress and significantly increased the performance of peas while reducing the levels of proline and antioxidant enzymes. So, it can safely be suggested to legume growers that RP1 strain could inexpensively be explored as an efficient biofertilizer for enhancing the production of legumes especially peas while growing even under fungicide (kitazin) enriched soils.

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Kitazin-pea interaction: understanding the fungicide induced nodule alteration, cytotoxicity, oxidative damage and toxicity alleviation by Rhizobium leguminosarum

Bio-effective disease control and plant growth promotion in lentil by two pesticide degrading strains of Bacillus sp.

Plant growth-promoting rhizobacteria (PGPR) are soil bacteria, colonizing rhizospheric region of plants, which have the ability to enhance plant health and promote plant growth by increasing seed emergence, plant weight, and yields to a wide variety of crops either through direct action or via biological control of plant diseases. PGPR improve plant growth by either fixing atmospheric nitrogen; solubilizing insoluble phosphates and iron and producing plant growth regulators (PGRs) like auxins, gibberellins, cytokinins, etc.; or suppression of deleterious root-colonizing microorganisms including plant pathogens through antibiosis, i.e., production of fungitoxic compounds, competition with pathogenic microorganisms for nutrients by producing siderophores, or niche exclusion. Indiscriminate use of different chemicals in the form of fertilizers and pesticides targeting to increase the agricultural produce for ever-increasing population outburst has led to the contamination of the groundwater, soil, and sediments. Accretion of diversified range of chemicals in significant quantities has a direct impact not only on the living beings but also on the environment. The ecological balance of the soil microorganisms has been distorted which show the negative impact on their rhizospheric competence. When exogenous PGPR are applied in this pesticide-infested soil, they not only hardly show their plant growth-promoting or disease-suppressing activities but also might not survive at all. Isolation of native PGPR from the pesticide-challenged rhizospheric soils mostly shows pesticide-tolerant/degrading properties. These PGPR might show the rhizospheric competence in similar pesticide-infested soil. These strains easily acclimatize in the pesticide-contaminated microenvironment in soil and show their plant growth-promoting and pathogen-suppressive activities.

Pesticide Tolerant Rhizobacteria: Paradigm of Disease Management and Plant Growth Promotion

The study investigates the potential of substitution of the conventional carbohydrate nutrient (cellulose) in media with cheap agro-residues for cellobiose dehydrogenase production by Termitomyces clypeatus (CDHtc) under submerged conditions. Different agro-residues tested for enzyme production were characterized using FTIR and XRD analysis. As CDHtc production was highest with tamarind kernel powder (TKP), it was selected for process optimizations through shake-flask fermentations. The optimized parameters were then applied to batch cultures in a 5 L bioreactor that gave enzyme yield (57.4 U mL⁻¹) similar to that obtained under shake-flask fermentations (57.05 U mL⁻¹). The study also made an attempt to predict CDHtc production with respect to time of fermentation and mycelial growth. The specific growth rate and carrying capacity of the mycelia were also determined, and the values lie in the ranges of 0.024-0.027 h⁻¹ and 7.2-7.1 mg mL⁻¹, respectively.

Tamarind kernel powder: a novel agro-residue for the production of cellobiose dehydrogenase under submerged fermentation by Termitomyces clypeatus.

Comparative Study of Fruiting Body Production of some Oyster Mushroom in Two Different Temperatures 
Oyster mushroom (Pleurotus spp.) are widely cultivated throughout the world for nutritional as well as for medicinal purposes. To see the effect of temperature on yield, efficiency and protein content of different oyster mushroom, eight oyster mushroom i.e. Pleurotus ostreatus, P. florida, P. sajorcaju, P. eryngii. P. pulmonarius, P. citrinopileatus, P. flabellatus and P. fossulatus were taken. 10% spawn of respective mushroom strains were inoculated in overnight wetted non-sterilized rice straw and kept in two different temperatures (18°C and 25°C). In 18°C all the species produced fruiting bodies whereas in 25°C, all the tested species except P. fossulatus could produce the fruiting bodies. Considering the time as a main factor in fruiting, a new parameter Biological efficiency day-1 (BED) is introduced to better understand the fruiting efficiency in respect to time. It was found that beyond second flushes fruiting was not commercially sustainable. In lower temperature (18˚C) P. florida (ITCC 3308) showed the highest BED value whereas P. pulmonarius showed the highest BED value in higher temperature (25˚C). The protein content of the fruiting bodies varied significantly from species to species though temperature has no such effect. The fruiting life varied from 4-7 days in all the tested mushrooms except P. fossulatus which was much longer (>25 days). In present experimental condition P. fossulatus showed the most temperature sensitivity, P. pulmonarius showed the least temperature sensitivity whereas all the other species showed moderate temperature sensitivity.

Nirmalendu Das

Papers

Bio-effective disease control and plant growth promotion in lentil by two pesticide degrading strains of Bacillus sp.

Pesticide Tolerant Rhizobacteria: Paradigm of Disease Management and Plant Growth Promotion

Tamarind kernel powder: a novel agro-residue for the production of cellobiose dehydrogenase under submerged fermentation by Termitomyces clypeatus.

Comparative Study of Fruiting Body Production of some Oyster Mushroom in Two Different Temperatures