Comparative Study of Extracellular Proteolytic, Cellulolytic, and Hemicellulolytic Enzyme Activities and Biotransformation of Palm Kernel Cake Biomass by Lactic Acid Bacteria Isolated from Malaysian Foods.

Rosfarizan Mohamad,Zulkifli Idrus,Fu Haw Lee,Teck Chwen Loh,Suet Ying Wan,Raha Abdul Rahim,Hooi Ling Foo

doi:10.3390/ijms20204979

Rosfarizan Mohamad, Zulkifli Idrus + Show 5 more

Open Access

https://doi.org/10.3390/ijms20204979

Copy DOI

Abstract

Biotransformation via solid state fermentation (SSF) mediated by microorganisms is a promising approach to produce useful products from agricultural biomass. Lactic acid bacteria (LAB) that are commonly found in fermented foods have been shown to exhibit extracellular proteolytic, β-glucosidase, β-mannosidase, and β-mannanase activities. Therefore, extracellular proteolytic, cellulolytic, and hemicellulolytic enzyme activities of seven Lactobacillus plantarum strains (a prominent species of LAB) isolated from Malaysian foods were compared in this study. The biotransformation of palm kernel cake (PKC) biomass mediated by selected L. plantarum strains was subsequently conducted. The results obtained in this study exhibited the studied L. plantarum strains produced versatile multi extracellular hydrolytic enzyme activities that were active from acidic to alkaline pH conditions. The highest total score of extracellular hydrolytic enzyme activities were recorded by L. plantarum RI11, L. plantarum RG11, and L. plantarum RG14. Therefore, they were selected for the subsequent biotransformation of PKC biomass via SSF. The hydrolytic enzyme activities of treated PKC extract were compared for each sampling interval. The scanning electron microscopy analyses revealed the formation of extracellular matrices around L. plantarum strains attached to the surface of PKC biomass during SSF, inferring that the investigated L. plantarum strains have the capability to grow on PKC biomass and perform synergistic secretions of various extracellular proteolytic, cellulolytic, and hemicellulolytic enzymes that were essential for the effective biodegradation of PKC. The substantial growth of selected L. plamtraum strains on PKC during SSF revealed the promising application of selected L. plantarum strains as a biotransformation agent for cellulosic biomass.

Highlights

The second-millennium biotechnology approaches of the biotransformation of agricultural biomass into various useful products mediated by hydrolytic enzymes [1] produced by various microorganisms are vital and desperately need to be developed to facilitate the environmental challenges that are currently being encountered worldwide
The results obtained in this study demonstrated that the specific extracellular cellulolytic, hemicellulolytic, and proteolytic activities of L. plantarum strains were varied considerably under three different pH (5.0, 6.5, and 8.0) conditions
The L. plantarum stains tested in the present study showed the production of a cocktail mixture of extracellular proteases, cellulases, hemicellulases, and endoprotease, all of which were active from acidic to alkaline conditions, inferring the versatile extracellular hydrolytic enzyme capacity of the studied L. plantarum strains

Summary

Introduction

The second-millennium biotechnology approaches of the biotransformation of agricultural biomass into various useful products mediated by hydrolytic enzymes [1] produced by various microorganisms are vital and desperately need to be developed to facilitate the environmental challenges that are currently being encountered worldwide. The current biotechnological strategies focus mainly on energy production (biofuel) [3,4], biopolymer production [5], food production, and other value-added products, such as enzymes, biological media, metabolites, and vitamins [6,7,8,9,10,11] Agricultural biomasses, such as bagasse, straws and stems, cobs, fruit peels, and husks, are excellent carbon sources, attributing to their lignocellulosic content. Cellulases and hemicellulases that secreted by microorganisms via the fermentation process are essential enzymes required for the biotransformation of agricultural biomasses to simple sugar. The cellulases and hemicellulases produced by microorganisms have been reported to be secreted in free form or multi-enzyme complexes. Various fungus species (Trichoderma sp. [16,17,18], Aspergillus sp. [19], Phanercochaete chrysosporium [20,21]) and bacterial species (Bacillus sp. [22], Clostridium sp. [23], Pseudoxanthomonas sp. [24], Ochrobactrum sp. [25,26], Klebsiella sp. [27], Cellulomonas sp. [28,29], Acinetobacter sp. [30], and Pseudomonas sp. [31]) have been reported for their cellulases and hemicellulases activities

Objectives

Methods

Results

Discussion

Conclusion