Enhancement of the ligninolytic activity of Lysinibacillus sphaericus by the addition of MnSO4 and its impact on subsequent methane production from Oil Palm Empty Fruit Bunches (OPEFB)

Abstract

Palm empty fruit bunches (OPEFB) is a recalcitrant agricultural waste not readily digested which is produced in abundance. The recently isolated bacteria, Lysinibacillus sphaericus is a facultative anaerobe which can digest lignin. The objective of this study was to determine if the addition of L. sphaericus and MnSO4 could aid the bioconversion of OPEFB, and if this could enhance methane production during subsequent anaerobic digestion (AD). The untreated OPEFB had a specific methane potential of 0.099 L/g VS which was doubled following pre-treatment with L. sphaericus. In the presence of 0.25 mM MnSO4 a further 1.5-fold increase in methane production was observed. This illustrates for the first time how the addition of inducers (MnSO4) can significantly enhance this bacteria's ability to degrade lignocellulose through enhancement of its lignin degrading enzymes. Thus, enabling this agricultural waste to be utilised more effectively for biogas production.