A novel method for the identification and enumeration of microorganisms with potential for suppressing fungal plant pathogens

Abstract

This paper describes a method that allowed counting of both the total culturable and antagonistic microorganisms in a given source such as compost. Fusarium solani, used as the test fungus, was spreadplated on quarter-strength (1/4) potato dextrose agar (PDA), its surface was exposed in a laminar flow for 4 h and then another layer (2-3 mm thick) of 1/4 PDA was poured over it, on which an appropriate dilution of a compost sample was spread-plated. Microorganisms in the compost samples appeared first, and were counted as total culturable organisms. Plates were further incubated until F. solani grew through the upper layer of PDA (generally in 4-8 days) and covered the whole plate including most of the microbial colonies, except for a few which had a halo around them. These were counted as antagonistic, and they were isolated and purified for further studies. The population of bacteria in the six specific compost samples (called Biodynamic or BD preparations by organic farmers) ranged from 3.45 log 10 (in BD502) to 8.59 log 10 (in BD504) per gram of materials. The population of antagonistic bacteria was counted for three of the six compost samples, and ranged from 3.24 log 10 (in BD502) to 6.90 log 10 (in BD500). Of the 67 bacterial isolates showing a halo that were assembled from different sources, 17 suppressed at least 1 of the 4 plant pathogenic fungi against which these were evaluated using the dual culture method.

Plant Growth Promoting Bacteria from Cow Dung Based Biodynamic Preparations

“…'Panchagavya' (PG; Sanskrit for a blend of 'five products from cow') is a traditional product prepared in India by fermenting cow dung, cow urine, milk, curd and clarified butter (ghee) [1]. BD500, a biodynamic preparation that is also called as horn manure and 'Cow pat pit' (CPP) are preparations from cow dung that are used in organic farming [2,3]. Biodynamic products are included in the list of materials and techniques permitted in organic farming by an EC regulation (834/2007).…”

Current status of cow dung as a bioresource for sustainable development

“…Many biodynamic preparations obtained from cow dung have shown antagonistic effect against plant pathogens such as Rhizoctonia bataticola (Rupela et al 2003;Somasundaram et al 2007;Radha and Rao 2014). An investigation by Mary et al (1986) revealed cow dung extract to be more effective than antibiotics like Penicillin, Paushamycin and Streptomycin in controlling bacterial blight of rice.…”

Bacillus cereus and Enterobacter cancerogenus screened for their efficient plant growth promoting traits rhizobacteria (PGPR) and antagonistic traits among sixteen bacterial isolates from rhizospheric soils of Pigeon Pea

“…To be an effective PGPR, bacteria must be able to colonize roots because bacteria need to establish itself in the rhizosphere at population densities sufficient to produce the beneficial effects. The exact mechanism by which PGPR stimulate plant growth is not clearly estimated, although several hypothesis such as production of phytohormones, activation of phosphate solubilization and promotion of the mineral nutrient uptake are usually believed to be involved (Rupela and Kumar, 1999).…”