Optimization of Lipase Production in Solid-State Fermentation by Rhizopus Arrhizus in Nutrient Medium Containing Agroindustrial Wastes

Georgi Dobrev,Boriana Zhekova,Anelia Hambarliiska,Valentina Dobreva,Hristina Strinska

doi:10.2174/1874070701812010189

Abstract

Background: Rhizopus arrhizus is a potential microorganism for lipase production. Solid-state fermentation is used for microbial biosynthesis of enzymes, due to advantages, such as high productivity, utilization of abundant and low-cost raw materials, and production of enzymes with different catalytic properties. Objective: The objective of the research is optimization of the conditions for lipase production in solid-state fermentation by Rhizopus arrhizus in a nutrient medium, containing agroindustrial wastes. Method: Biosynthesis of lipase in solid-state fermentation by Rhizopus arrhizus was investigated. The effect of different solid substrates, additional carbon and nitrogen source, particles size and moisture content of the medium on enzyme production was studied. Response surface methodology was applied for determination of the optimal values of moisture content and tryptone concentration. A procedure for efficient lipase extraction from the fermented solids was developed. Results: Highest lipase activity was achieved when wheat bran was used as a solid substrate. The addition of 1% (w/w) glucose and 5% (w/w) tryptone to the solid medium significantly increased lipase activity. The structure of the solid medium including particles size and moisture content significantly influenced lipase production. A mathematical model for the effect of moisture content and tryptone concentration on lipase activity was developed. Highest enzyme activity was achieved at 66% moisture and 5% (w/w) tryptone. The addition of the non-ionic surfactant Disponyl NP 3070 in the eluent for enzyme extraction from the fermented solids increased lipase activity about three folds. Conclusion: After optimization of the solid-state fermentation the achieved 1021.80 U/g lipase activity from Rhizopus arrhizus was higher and comparable with the activity of lipases, produced by other fungal strains. The optimization of the conditions and the use of low cost components in solid-state fermentation makes the process economicaly effective for production of lipase from the investigated strain Rhizopus arrhizus.

Highlights

Lipases are one of the most important classes of industrial enzymes
Highest lipase activity was achieved when wheat bran was used as a solid substrate
Effect of Solid Substrate on Lipase Biosynthesis in Solid-State Fermentation (SSF) The choice of solid substrate is of great importance to SSF, because in addition to being a source of nutrients, it forms the structure of the culture medium and determines the possibility of mass and heat transfer

Summary

Introduction

Lipases (triacylglycerol acylhydrolases, EC 3.1.1.3) are one of the most important classes of industrial enzymes. Lipases hydrolyse triglycerides into diglycerides, monoglycerides, glycerol and fatty acids They are able to catalyse hydrolysis and synthesis reaction (esterification and transesterification) in media with low water content [2]. SSF was used for enzymes production, due to its advantages, such as high productivity, generation of high-quality products, and use of abundant and low-cost raw materials such as agro industrial wastes. The use of complex matrix of agro industrial wastes as a culture medium induces the production of different hydrolytic enzymes such as amylases and proteases in the same fermentation batch, or even pools of lipases with different catalytic properties [4]. Solid-state fermentation is used for microbial biosynthesis of enzymes, due to advantages, such as high productivity, utilization of abundant and low-cost raw materials, and production of enzymes with different catalytic properties

Methods

Results

Conclusion