RESEARCH ARTICLE


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



Georgi Dobrev1, Hristina Strinska1, Anelia Hambarliiska1, Boriana Zhekova1, *, Valentina Dobreva2
1 Department of Biochemistry and Molecular Biology, University of Food Technologies, 26 Maritza Blvd., 4002 Plovdiv, Bulgaria
2 Department of Engineering Ecology, University of Food Technologies, 26 Maritza Blvd., 4002 Plovdiv, Bulgaria


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© 2018 Dobrev et al.

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: (https://creativecommons.org/licenses/by/4.0/legalcode). This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

* Address correspondence to this author at the Department of Biochemistry and Molecular Biology, University of Food Technologies, 26 Maritsa Blvd., 4002 Plovdiv, Bulgaria; Tel: 00359 32 603 605; E-mail: zhekova_b@yahoo.com


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.

Keywords: Lipase, Solid-state fermentation, Rhizopus arrhizus, Response surface methodology, Agroindustrial wastes, Biosynthesis.