OPTIMIZATION OF AGITATION AND INCUBATION PERIOD ON PRODUCTION OF MANNANASE BY BACILLUS VELEZENSIS NRC-1 USING BENCH-SCALE BIOREACTOR

Tarek Mazeed

doi:10.21608/ajps.2012.7243

Abstract

The effect of agitation speed and incubation period on the production of mannanase enzyme by Bacillus velezensis NRC-1 using bench-scale bioreactor at 45oC was investigated. Results revealed that the increase in agitation speed from 200 to 800 rpm resulted in a significant increase in mannanase production to 21.04 U/mL. The increase in agitation speed affected dissolved oxygen (DO) concentration which in turn affected cell growth and mannanase production. The maximum mannanase production in the bioreactor was attained after 72 h of incubation at 45 oC. Mannanase activity in the bioreactor (21.04 U/mL) while much higher than that obtained from the shake flask fermentation (15.6 U/mL) also the incubation period decreased from 7 days in shake flask fermentation to 3 days in bioreactor.

Highlights

Beta-mannanase (Endo-1,4-β-D-mannanase, EC 3.2.1.78) is a crucial enzyme that catalyzes the random cleavage of β-D-1,4 mannopyranosyl linkages within the main chain of galactomannan, glucomannan, galactoglucomannan and mannan (Stoll et al, 1999)
Mannanases have been reported from different organisms; bacteria (Mendoza et al, 1995), fungi (Arcand et al, 1993), higher plants (Bewley et al, 1997) and animals (Yamaura and Matsumoto, 1993). β-Mannanases have numerous applications in the food, feed, as well as pulp and paper industries (Godfrey, 1983; Wong et al, 1993). β-Mannanase can be mass cultivated in industrial fermenters by using batch fermentation process
Much work has been done on screening of high β-mannanase producing microorganisms, these efforts have primarily been confined to culture medium and conditions in shake flask studies (Akino et al, 1987; Ratto and Poutanen, 1988 and Araujo and Ward, 1990)

Summary

Introduction

Beta-mannanase (Endo-1,4-β-D-mannanase, EC 3.2.1.78) is a crucial enzyme that catalyzes the random cleavage of β-D-1,4 mannopyranosyl linkages within the main chain of galactomannan, glucomannan, galactoglucomannan and mannan (Stoll et al, 1999). For full-scale production system, it is essential to devise a scale-up strategy using bioreactor that would adopt desired level of agitation and aeration rates (in the fermentor), which in turn would give comparable or better yields relative to those obtained from shake flask study. This is necessary as it would enable one to minimize production cost and optimize the cost-effectiveness for the overall production process (Feng et al, 2003). The objective of this study is to investigate the desired combination of agitation, and incubation period that would yield the highest β-mannanase production by B. velezensis nrc-1 in fermenter scale

Objectives

Methods

Results