Abstract
At present, due to the health side effects of chemically synthesized coloring agents, naturally produced coloring agents were favored. From all naturally produced coloring sources, microbial pigments have been given precedence, due to easy manipulation of the microorganisms and optimization of the production processes. The main aim of this article is to report the characteristics and factors affecting growth and pigment production by bacterium isolate Mif41. The soil samples were collected and serially diluted from 10 -1 to 10 -6 and each dilution was plate on the sterilized Glucose, mannitol, Tryptose Yeast extract Agar (GMTYEA) medium and incubated at 28°C under aerobic condition. After 48h of incubation the yellow pigmented bacterium isolate was picked and purified by repeated streaking on GMTYEA and the pure culture was maintained on slant at 4°C. The pure culture of the bacterium isolate was characterized morphologically and biochemically. Both extracellular and intracellular pigments obtained from the bacterium isolate were analyzed by using UV-visible spectrophotometer. Effect of carbon sources, nitrogen sources, medium PH, incubation temperature and effect of salt concentrations on growth and pigment production were evaluated. The morphological and biochemical characterization of the bacterium isolate tentatively suggested as Pseudomonas sp. From the different carbon sources tested fructose favored maximum extracellular and intra cellular pigmentation while sorbitol was found minimal in this respect. All the organic sources of nitrogen stimulated growth and pigmentation while all the inorganic sources of nitrogen were inhibitory for growth and pigmentation. Incubation temperatures of 20-28°C were favored growth and pigmentation while incubation temperature above 30 were highly limiting for growth and pigmentation. Medium PH 8 found to be favorable for growth and pigmentation while acidic and basic pH were limiting for growth and pigmentation. 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 bacterium isolate Mif41 is able to produce different colored pigments under different nutritional and environmental conditions suggesting that this bacterium isolate will be considered as a candidate for the industrial production of pigments which will be applied in various industries. Key words/phrases : Bacterium isolate, Natural color, pigment, Rhizosphere soil, Synthetic color DOI: 10.7176/JBAH/10-18-02 Publication date: September 30 th 2020
Highlights
Pigments are the chemical substances that absorb the light of visible region and with uniqueness of significance to many industries (Desai, 2018)
Isolation of Pigment Producing Bacteria From the different soils samples collected from the rhizosphere of some tree from the main campus of the Ambo University, a number of colored colonies of bacteria were isolated, for further characterization, growth and pigment production optimization studies, the extensively yellow pigmented isolate Mif41 was selected.(Fig 1)
The results of this study is in line with the reports in the literature, that stated that, yellow pigmented bacteria are widely present in soil and based on the isolates found they can effectively produce amylase enzyme and carotenoid pigment which has a potential for application as food supplement and as antioxidant (Aishwarya and Binita, 2018)
Summary
Pigments are the chemical substances that absorb the light of visible region and with uniqueness of significance to many industries (Desai, 2018). They produce the colors that are sensible at each pace of our lives and are in leaves, fruits, vegetables and flowers. Synthetic dyes generally contain benzene backbone moiety (aromatic) that makes them more recalcitrant in nature. Their toxicity is increased by substituent like nitro, methyl, methoxy or halogen groups. Food and drug administration reported that dyes containing metals such as lead, chromate and copper sulphate possess the potential risk of causing serious health and environmental hazards (FDA, 1993)
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