Isolation And Characterization Of Pigment Producing Bacteria From Jibat Forest Soils And Optimization Of Conditions For Pigment Production

Abstract

Nature is rich in color and pigment producing microorganisms like bacteria, fungi and yeasts are richly available in the Environment. From all naturally produced coloring sources, microbial pigments are preferred, due to their stability, use various cheap sources for growth for pigment production, production of pigments in larger amount and availability for cultivation throughout the year. The main aim of this thesis was to isolate and characterize pigment producing bacterial isolates from Jibat forest and optimization of conductions for the pigment production. The soil samples were collected and serially diluted from 10-1 to 10-6 and each dilution was plate on the sterilized Glucose, mannitol, Tryptone Yeast extract Agar (GMTYEA) medium and incubated at 28°C under aerobic condition. From the different soil samples studied, two bacteria isolates Yellow (S08I4) from Gravillae Robusta and Red (S07I20) from dead wood were selected for further investigation and pigment. After 48hrs of incubation yellow and red pigmented bacteria isolate were picked and purified by repeated streaking on GMTYEA and the pure culture was maintained on slant GMTYEA at 4°C. Both extracellular and intracellular pigments obtained from the bacterial isolates were analyzed by using UV-visible spectrophotometer. Effect of carbon sources, nitrogen sources, pH, incubation temperature and effect of salt concentrations on growth and pigment production were evaluated. The morphological and biochemical characterization of the bacterial isolates tentatively suggested as Serratia and Micrococcus. From the different carbon sources tested dextrose favored maximum extracellular (OD 2.742) and intra cellular (OD 2.799) red pigmentation while myo-inostol was found minimal extracellular (OD 1.338) and intra cellular (OD 1.00) yellow in this respect. For both bacterial isolates Red (S07I20) yeast extract( OD 2.45) enhanced more growth and pigmentation and for Yellow (S08I4)( OD 0.014) Therefore, organic sources of nitrogen enhanced more growth and pigmentation, while inorganic sources of nitrogen were found not useful for both growth and pigmentation. Genus level identification of bacteria isolated from Jibat forest bacterial isolate (S08I4) Yellow colored was estimated as Micrococcus while bacterial isolate (S07I20) Red colored was estimated as Serratia. The optimum pigmentation of each bacterial isolates was at 28°C with OD value of 1.1 at 350nm. The optical density of the pigment of both bacterial isolates was higher around neutrality (pH 7) the pigmentation was gradually decline toward alkaline and acidic pH. Lower salt concentration was found to favor the growth and pigmentation, while increased concentration were found to be limiting. The results of this study clearly indicated that the bacteria isolated from Jibat forest soil is able to produce different colored pigments under different nutritional and environmental conditions suggesting that this bacterial isolates will be considered as a candidate for the industrial production of pigments which will be applied in various industries.