Potential of Rhodobacter capsulatus Grown in Anaerobic-Light or Aerobic-Dark Conditions as Bioremediation Agent for Biological Wastewater Treatments

Abstract

Abstract:The use of microorganisms to clean up wastewater provides a cheaper alternative to the conventional treatment plant. The efficiency of this method can be improved by the choice of microorganism with the potential of removing contaminants. One such group is photosynthetic bacteria. Rhodobacter capsulatus is a purple non-sulfur bacterium (PNSB) found to be capable of different metabolic activities depending on the environmental conditions. Cell growth in different media and conditions was tested, obtaining a concentration of about 10 8 CFU/mL under aerobic-dark and 10 9 CFU/mL under anaerobic-light conditions. The biomass was then used as a bioremediation agent for denitrification and nitrification of municipal wastewater to evaluate the potential to be employed as an additive in biological wastewater treatment. Inoculating a sample of mixed liquor withdrawn from the municipal wastewater treatment plant with R. capsulatus grown in aerobic-dark and anaerobic-light conditions caused a significant decrease of N-NO 3 (>95%), N-NH 3 (70%) and SCOD (soluble chemical oxygen demand) (>69%), independent of the growth conditions. A preliminary evaluation of costs indicated that R. capsulatus grown in aerobic-dark conditions could be more convenient for industrial application.

Anoxic growth optimization for metal respiration and photobiological hydrogen production by arsenic‐resistant Rhodopseudomonas and Rhodobacter species

“…However, Rhodobacter sp. PI3 showed better aerobic growth for both carbon sources as compared to R. palustris (PI5), as reported by Costa et al . Isolates PIA4 and PI1 utilized citrate only in aerobic conditions.…”

Shifts in microbial community structure and diversity in a novel waterfall biofilm reactor combined with MBBR under light and dark conditions

“…41,42 Deltaproteobacteria is a kind of anaerobic microorganisms, which establish only in the later stages presumably due to their slow growth and requirement for anoxic conditions. 43 Previous researches show that illumination can promote the process of biolm maturation 44,45 and the biolm in light was more compact, and the gap structure more homogeneous. In the same time, IC contribute to a suitable environment for Deltaproteobacteria.…”

A simple culture technique of Rhodobacter azotoformans EBN-7 for public use: application to NH4+-N removal in shrimp aquaculture water

“…The best growth was achieved when R. capsulatus BR was cultivated on the basal medium. When cultivated on the basal medium, the number of viable cells of R. capsulatus BR maximally reached 4.75 × 10 9 after 89 h, which was relatively higher than that previously reported-3 × 10 8 under dark-aerobic conditions or 3 × 10 9 under photo-anaerobic conditions (Costa et al, 2017). Although pH change was not significant during the lag phase, pH increased as cells grew exponentially (Fig.…”