Effects of illuminance and nutrients on bacterial photo-physiology of hydrocarbon degradation

Bacterial photophysiology was previously limited to photoautotrophs. The discovery of bacteriophytochromes in non-photoautotrophs raised a question whether these non-photoautotrophs are affected by the presence or absence of light? In this research work for the first time, bacterial hydrocarbon degradation and biomass production was studied under the influence of nutrients, illuminance (light flux) and time. An experimental model was designed, with six isolated bacterial strains (Pseudomonas poae BA1, Pseudomonas rhizosphaerae BP3, Bacillus thuringiensis BG3, Acinetobacter bouvetii BP18, Pseudomonas proteolytica BG31 and Stenotrophomonas rhizophila BG32) under four different conditions of nutrient media and illuminance at three time intervals of 15, 30, and 45 days without shaking. All strains showed statistically higher hydrocarbon degradation under nutrient rich, dark conditions. Highest biodegradation (80.8, 79.4, and 78.7 mg) was observed in BG31, BG17 and BG3 respectively. Nutrient rich media along with dark conditions improved the biomass production, and when media was nutrient deprived, higher biomass was produced in the presence of light. This work proved that light and nutrients significantly affect bacterial populations and hydrocarbon degradation. The optimal use of these parameters could facilitate to achieve the goal of remediation of hydrocarbon contaminated sites. (C) 2016 Elsevier B.V. All rights reserved.