Selection of effective bio-​antagonistic bacteria for biological control of tomato wilt caused by Fusarium oxysporum F. sp. lycopersici

Bacteria from the rhizoplane soil and surrounding soil of healthy and Fusarium oxysporum diseased tomato plants of district regions of Karnataka were collected. The best bacterial strains, based on their ability to control development of Fusarium oxysporum isolate, were identified as BS1, BS5 and BS18. All bacterial isolates resulted effective for the in vitro control of growth of Fusarium oxysporum, where the control mechanisms used by the bacteria do not involve the secretion of fungal cell wall hydrolytic enzymes. On the other hand, all bacteria grew well in conditions similar to those that can be found at the field level (considering pH, salinity, Fe3+ and temp.) and showed a good capacity of tomato root colonization. These results suggest that Pseudomonas fluorescens isolates studied have an excellent potential to be used as biocontrol agents of Fusarium oxysporum in tomato greenhouses at the field level

Biological Control of F. Oxysporum F. Sp. Lycopersici Causing Wilt of Tomato by Pseudomonas Fluorescens

Abstract- Pseudomonas fluorescens is one of the major fungal biocontrol agents found in the soil and the rhizosphere of various crop systems. Ten isolates of P.fluorescens were isolated from rhizosphere soil samples collected from various tomato-growing fields and evaluated for their efficacy in increasing seed quality variables of tomato and in inhibiting the mycelial growth of Fusarium oxysporum. Pseudomonas isolate 2 produced effective results and was selected and mass multiplied. Talc and sodium alginate formulations of mass multiplied using different agents were prepared and evaluated for their effects against fusarium wilt under greenhouse conditions. Fresh cultures of Pf2 isolate was found to increase seedling emergence and reduce fusarium wilt disease incidence when compared to the control and the formulations

Assessment of coliform contamination in drinking water from source to point of use in Mysore city of Karnataka, India

Drinking water supply of Mysore city was assessed for coliform contamination. A 277 drinking water samples were randomly collected from different water sources such as bore wells, taps of consumer points and stored household water samples. The samples were analyzed for microbial parameters like heterotrophic plate count and coliform count. Out of 226 samples from consumer points, 80 samples were contaminated with enteric bacteria. Nearly 325 isolates of coliform were identified of which there were 79 E. coli, 26 Salmonella, 92 Klebsiella and 98 Citrobacter isolates. From the study, the isolation of pathogenic microorganisms indicated that the stored household water was unsafe. Coliform contamination in household water was high even when source water was of good quality. The present study highlights the population’s hygiene, health behavior and environmental sanitation. Coliform in stored household water suggests that improvement in behavior and water hygiene practices can improve the household water quality

Effect of triacontanol on the seed quality of maize, paddy and sunflower

The seeds of maize, paddy and sunflower were treated with Triacontanol (tria), a natural primary alcohol of plants, and seed quality parameters were evaluated. All three concentrations (1, 5, and 10 ppm) of tria significantly increased the percentage germination of seeds over control. However, 10 ppm gave best results. Vigour index of maize seeds treated with 5 and 10 ppm was not significantly different but it was significant over 1 ppm treatment and controls. In paddy and sunflower, 10 ppm tria was superior over other concentrations and controls, in enhancing the seed vigour. In paddy the three concentrations of tria had same effect on field emergence but it was significant over controls. In sunflower, and maize the field emergence was highest in seeds treated with 10 ppm tria over other two concentrations and control. Triacontanol had no effect on seed mycoflora

Mycogenic Synthesis of Extracellular Zinc Oxide Nanoparticles from Xylaria Acuta and its Nanoantibiotic Potential

PurposeThe study aimed to find an effective method for fungal-mediated synthesis of zinc oxide nanoparticles using endophytic fungal extracts and to evaluate the efficiency of synthesized ZnO NPs as antimicrobial and anticancerous agents.MethodsZinc oxide nanoparticles (ZnO NPs) were produced from zinc nitrate hexahydrate with fungal filtrate by the combustion method. The spectroscopy and microscopy techniques, such as ultraviolet-visible spectroscopy, Fourier transform infrared spectroscopy (FT-IR), powder X-ray diffraction (PXRD), scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDX), dynamic light scattering (DLS), and transmission electron microscopy (TEM) with selected area electron diffraction (SAED), were used to characterize the obtained product. Antibacterial activity on Gram-positive (Staphylococcus aureus and Bacillus cereus) and Gram-negative (Pseudomonas aeruginosa and Escherichia coli) samples was tested by broth microplate dilution technique. ZnO NPs antifungal activity was determined against plant pathogenic and regular contaminating fungi using the food-poison method. The anticancerous assay of the synthesized ZnO NPs was also investigated by cell uptake, MTT assay, and apoptosis assay.ResultsThe fungal synthesized ZnO NPs were pure, mainly hexagonal in shape and size range of 34–55 nm. The biosynthesized ZnO NPs could proficiently inhibit both Gram-positive and Gram-negative bacteria. ZnO NPs synthesized from fungal extract exhibited antifungal activity in a dose-dependent manner with a high percentage of mycelial inhibition. The cell uptake analysis of ZnO NPs suggests that a significant amount of ZnO NPs (1 μg/mL) was internalized without disturbing cancer cells’ morphology. As a result, the synthesized ZnO NPs showed significant anticancer activity against cancer cells at 1 μg/mL concentration.ConclusionThis fungus-mediated synthesis of ZnO NPs is a simple, eco-friendly, and non-toxic method. Our results show that the synthesized ZnO NPs are an excellent novel antimicrobial and anticancer agent. Further studies are required to understand the mechanism of the antimicrobial, anticancerous action of ZnO NPs and their possible genotoxicit

Molecular phylogeny, pathogenicity and toxigenicity of Fusarium oxysporum f. sp. lycopersici

The present study aimed at the mol. characterization of pathogenic and non pathogenic F. oxysporum f. sp. lycopersici strains isolated from tomato. The causal agent isolated from symptomatic plants and soil samples was identified based on morphol. and mol. analyses. Pathogenicity testing of 69 strains on five susceptible tomato varieties showed 45​% of the strains were highly virulent and 30​% were moderately virulent. Mol. anal. based on the fingerprints obtained through ISSR indicated the presence of wide genetic diversity among the strains. Phylogenetic anal. based on ITS sequences showed the presence of at least four evolutionary lineages of the pathogen. The clustering of F. oxysporum with non pathogenic isolates and with the members of other formae speciales indicated polyphyletic origin of F. oxysporum f. sp. lycopersici. Further anal. revealed intraspecies variability and nucleotide insertions or deletions in the ITS region among the strains in the study and the obsd. variations were found to be clade specific. The high genetic diversity in the pathogen population demands for development of effective resistance breeding programs in tomato. Among the pathogenic strains tested, toxigenic strains harbored the Fum1 gene clearly indicating that the strains infecting tomato crops have the potential to produce Fumonisin