ISOLATION AND IDENTIFICATION OF SOME PPFMs BACTERIAL ISOLATES AND THEIR POTENTIALITY AS BIOFERTILIZERS AND BIOCONTROL AGENTS TO Rhizoctonia solani

Abstract

A total of 12 isolates of pink-pigmented, facultative methylotrophic bacteria (PPFMs) were isolated on selective AMS medium from clay soil. Samples were collected from two locations (Sidi Salem and Agricultural Farm, Sakha Agri. Res. Station). There after, all the classical recommended methods used for identification of all the obtained isolates were carried out including cultural, morphological, microscopical as well as biochemical characteristics. The results revealed that all the isolates were gram negative, rod shaped, motile, colonies were light pink or pink or orange/pink in colour due to pigmentation. Biochemical characteristics revealed that all the isolates showed positive results for oxidase, catalase, urease and citirate test as well as indole production. None of the isolates showed positive results for casein hydrolysis. The isolates of ML4, ML8 and ML10 gave a positive reaction for starch hydrolysis test, while the others showed negative results. Regarding, cellulose degradation, the isolates ML2, ML7,ML8 and ML12 gave a positive reaction. The obtained results highly recommended that all the obtained isolates could be classified as follows: ML1and ML6 Methylobacterium radiotolerans; ML2 and ML5 Methylobacterium suomiense; ML3 Methylobacterium aminovorans; ML4 and ML9 Methylobacterium thiocyanatum; ML7, ML8 andML10 Methylobacterium rhodesianum; ML11 Methylobacterium fujisawaens and ML12 Methylobacterium rhodinum. Screening the isolates for beneficial growth characters and biocontrol agent to R. solani. In general, Methylobacterium rhodinum.and Methylobacterium aminovorans recorded the highest values of indole acetic acid production, 28.15 and 27.50 μg ml-1, and 70.41 and 67.46 μg ml-1 for GA production, and 0.580, 0.560 μ moles of siderophores production, and 1.217 and 1.193 mg N/g for fixed nitrogen respectively. Also, the two species exhibiting obvious antibiosis against R. solani as recorded 72.61 and 71.20% for inhibition of R. solani on PDA medium, and 69.30 and 66.80% for inhibition of R. solani on AMS medium respectively.