Microbial lipid accumulation through bioremediation of palm oil mill effluent using a yeast-bacteria co-culture

Co-cultures of different microorganisms are considered promising inocula for treating palm oil mill ef-fluents (POME) and producing value-added bio-products (e.g., biofuels and fatty acid-derived materials). However, the efficiency of yeast-bacteria co-culture for microbial lipid production through bioremedi-ation of wastewater remains a bottleneck. In this study, the performance of a co-culture for lipid accu-mulation through POME bioremediation was investigated using a yeast (Lipomyces starkeyi) and a bacterium (Bacillus cereus). A maximum biomass of 8.89 +/- 0.33 g/L and lipid production of 2.27 +/- 0.10 g/L were achieved by the co-culture inoculum, which were substantially higher than those of the mono-cultures. Besides, the co-culture inoculum attained a maximum chemical oxygen demand (COD) removal of 83.66 +/- 1.9%, while the individual cultures of B. cereus and L. starkeyi obtained 74.35 +/- 1.7% and 69.01 +/- 2.3%, respectively. The bioremediation efficiency was confirmed by the seed germination index (GI) of Vigna radiata (Mung bean). It was observed that the co-culture inoculum had a higher GI compared to the untreated POME and even the monoculture-treated POME. We argue that the symbiotic association of a yeast-bacteria co-culture in POME could be an attractive approach for achieving maximum biomass as well as lipid production and simultaneous bioremediation of POME. (c) 2021 Elsevier Ltd. All rights reserved.

Automated summary

The co-culture of yeast and bacteria showed promising results in treating palm oil mill effluents, achieving higher biomass and lipid production, as well as efficient chemical oxygen demand removal. The symbiotic association of the co-culture was also validated through the seed germination index of mung beans, indicating its potential for simultaneous bioremediation of POME.