Comparative performance and reusability studies of lipases on syntheses of octyl esters with an economic approach.

A suitable immobilized lipase for esters syntheses should be selected considering not only its cost. We evaluated five biocatalysts in syntheses of octyl caprylate, octyl caprate, and octyl laurate, in which conversions higher than 90% were achieved. Novozym®ï»¿ 435 and non-commercial preparations (including a dry fermented solid) were selected for short-term octyl laurate syntheses using different biocatalysts loadings. By increasing the biocatalyst's loading the lipase's reusability also raised, but without strict proportionality, which resulted in a convergence between the lowest biocatalyst loading and the lowest cost per batch. The use of a dry fermented solid was cost-effective, even using loadings as high as 20.0% wt/wt due to its low obtaining cost, although exhibiting low productiveness. The combination of biocatalyst's cost, esterification activity, stability, and reusability represents proper criteria for the choice. This kind of assessment may help to establish quantitative goals to improve or to develop new biocatalysts.

Bioprocess development for biolubricant production using microbial oil derived via fermentation from confectionery industry wastes.

Microbial oil produced from confectionery and wheat milling side streams has been evaluated as novel feedstock for biolubricant production. Nutrient-rich fermentation media were produced by a two-step bioprocess involving crude enzyme production by solid state fermentation followed by enzymatic hydrolysis of confectionery industry waste. Among 5 yeast strains and 2 fungal strains cultivated on the crude hydrolysate, Rhodosporidium toruloides and Cryptococcus curvatus were selected for further evaluation for biolubricant production based on fermentation efficiency and fatty acid composition. The extracted microbial oils were enzymatically hydrolysed and the free fatty acids were esterified by Lipomod 34-MDP in a solvent-free system with trimethylolpropane (TMP) and neopentyl glycol (NPG). The highest conversion yields were 88% and 82.7% for NPG esters of R. toruloides and C. curvatus, respectively. This study also demonstrates that NPG esters produced from microbial oil have promising physicochemical properties for bio-based lubricant formulations that could substitute for conventional lubricants.