The
wastewater burden and increased energy demands have spurred
interest in finding possible solutions that could concomitantly address
both issues. Microbial lipid production, together with the bioremediation
of wastewater, could be a promising solution to address both problems.
In this context, the present study was designed to evaluate the potential
of Bacillus cereus (B. cereus) for
accumulating microbial lipids through the bioremediation of palm oil
mill effluent (POME) in batch mode fermentation. Different dilutions
of POME media (25%, 50%, 75%, and 100%) were used to determine the
optimum POME concentration for enabling the maximum yield of biomass
and maximum lipid production. The 50% (v/v) POME was found to have
potential for the highest biomass growth (8.09 g/L) and lipid accumulation
(1.46 g/L), with a lipid content of 18.04% (dry weight basis). B. cereus accumulated a higher biomass and lipid content
than other bacterial strains, such as Rhodococcus opacus and Pseudomonas aeruginosa, under similar conditions.
On the other hand, the degree of bioremediation was assessed by evaluating
several wastewater parameters and determining the seed germination
index (GI) of Vigna radiata. POME treated with B. cereus displayed higher GI values than the untreated
samples due to the significant remediation of detrimental organics
present in the POME. This finding was further confirmed by the substantial
reduction in pollution load, particularly in chemical oxygen demand
(COD) and biochemical oxygen demand (BOD) for 50% POME, thus demonstrating
removal efficiencies of 79.35% and 72.65%, respectively. Therefore,
the results of this study suggest that B. cereus cultivation
in POME could be a promising technique for attaining higher biomass
growth and lipid production in conjunction with the bioremediation
of POME. The approach of achieving dual objectives that is utilized
in the present study provides a novel strategy for palm oil millers.