Effects of Some Heavy Metals on Growth, Protein Content and Pigment Production by Streptomyces Coelicolor SM1

Samyah D. Jastaniah and Majdah Mohamed Ahmed Aburas  

Biology Department, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia.

Corresponding Author E-mail: sdjastaniah@kau.edu.sa

DOI : http://dx.doi.org/10.13005/bbra/2352

ABSTRACT: Heavy metals consequently tend to accumulate in nature and in food chains causing many environmental and health problems. Heavy metals biosorption by bacteria grown in polluted environments is proved. In this study, the effects of heavy metals on bacterial growth, dry cell weights, pigment production, nitrogen content and protein synthesis were investigated. Two isolates belong to genus Streptomyces, Streptpmyces coelicolor SM1 and S. anulatus SM21 were grown in presence of different concentration of heavy metals. Streptpmyces coelicolor SM1 was more resistant to Cd⁺⁺, Cr⁺⁺⁺, Co⁺⁺ and Cu⁺⁺ compared to S. anulatus SM21, thus it was selected for more detail studies.  The minimal inhibitory concentration (MIC) of each element was calculated and lower concentrations of the calculated MIC of the metals which partially limited bacterial growth was used to determine their effect for 7 days on S. colicolor SM1 growth, pigment production, nitrogen and protein contents and % of heavy metal removal which varied according to the nature of the metal used and time. At concentrations below the MIC, Cadmium, Cobalt and Cupper inhibited pigment production by the selected Streptomyces compared to control. Growth, N content and protein generally increased by time up to 7 days while they decreased significantly by the presence of the tested heavy metals. All tested metals decreased protein synthesis. It was found that removal of heavy metal increased by time. After 7 days, Cadmium (38%) and Chromium (39%) were the most adsorbed elements by S. coelicolor SM1 followed by Cobalt (29%) and Copper (25%). In conclusion, Streptpmyces coelicolor SM1 can be used significantly to remove Cadmium, Chromium, Cobalt and Copper from heavy metal contaminated areas.

KEYWORDS: Protein; growth; pigment; inhibition; Streptomyces; heavy metals; bio-sorption

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