Abstract
This is the first report on the possible use of decanter cake waste (DCW) from palm oil industry as alternative nutrient sources and biomass support particles for whole-cell lipase production under solid-state fermentation (SSF) by newly isolated fungal Aspergillus sp. MS15 and their application as a low-cost and environment-friendly biocatalyst for biodiesel production. The results found that DCW supplemented with 0.1% K2HPO4, 0.05% MgSO4·7H2O, 1% peptone and 2% urea and pH adjusted to 6.0 was optimal for whole-cell lipase production. The optimal moisture content and fermentation temperature was 60% and 37.5 °C, respectively. Environmentally friendly biodiesel production, through either esterification or transesterification using whole-cell lipase immobilized on DCW as a biocatalyst, was optimized. The optimal reaction temperature for both reactions was 37 °C. The whole-cell lipase effectively esterified oleic acid into >95% biodiesel yield through esterification under optimal water activity at 0.71 and an optimal methanol to oleic acid molar ratio of 2:1, and also effectively transesterified palm oil under optimal water activity at 0.81 and an optimal methanol to oil molar ratio of 3:1. The fuel properties of produced biodiesel are close to the international biodiesel standards. These results have shown the circular utilization of palm oil mill waste for the low-cost production of an effective biocatalyst, and may contribute greatly to the sustainability of renewable bioenergy production.
Highlights
Introduction iationsBiodiesel is produced from vegetable oils by the chemical reaction of transesterification, but not by esterification
Ten fungal isolates were cultured on decanter cake waste (DCW) as their nutrient source and BSP through
Our results are in good agreement with the previous publications reported by Rakchai et al [1,2], Oliveira et al [12] and Hama et al [16]. They found that whole-cell lipase produced from different fungal strains, such as Aspergillus nomius, Aspergillus niger, Aspergillus oryzae, Aspergillus awamori, and Rhizopus oryzae, gave hydrolytic activity in a range of 0.10–20.70 U/g-dry cell weight
Summary
Biodiesel is produced from vegetable oils by the chemical reaction of transesterification, but not by esterification. It can be produced by the esterification of fatty acids in the presence of an alcohol (MetOH, EtOH) and catalyst (NaOH or KOH). Enzymatic transesterification is a more attractive method than chemical methods due to its mild reaction condition, lower energy requirement and more environmentally friendly process [3]. Lipases are wildly used as biocatalysts which are capable of catalyzing diverse reactions including hydrolysis, esterification and transesterification [4]. Microbial lipases are gaining increasing attention in industrial applications due to their high product yields and high stability [5].
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