Strategies for improving production performance of probiotic Pediococcus acidilactici viable cell by overcoming lactic acid inhibition

Majdiah Othman,Murni Halim,Mohd Rizal Kapri,Arbakariya B Ariff,Helmi Wasoh

doi:10.1186/s13568-017-0519-6

Abstract

Lactic acid bacteria are industrially important microorganisms recognized for fermentative ability mostly in their probiotic benefits as well as lactic acid production for various applications. Fermentation conditions such as concentration of initial glucose in the culture, concentration of lactic acid accumulated in the culture, types of pH control strategy, types of aeration mode and different agitation speed had influenced the cultivation performance of batch fermentation of Pediococcus acidilactici. The maximum viable cell concentration obtained in constant fed-batch fermentation at a feeding rate of 0.015 L/h was 6.1 times higher with 1.6 times reduction in lactic acid accumulation compared to batch fermentation. Anion exchange resin, IRA 67 was found to have the highest selectivity towards lactic acid compared to other components studied. Fed-batch fermentation of P. acidilactici coupled with lactic acid removal system using IRA 67 resin showed 55.5 and 9.1 times of improvement in maximum viable cell concentration compared to fermentation without resin for batch and fed-batch mode respectively. The improvement of the P. acidilactici growth in the constant fed-batch fermentation indicated the use of minimal and simple process control equipment is an effective approach for reducing by-product inhibition. Further improvement in the cultivation performance of P. acidilactici in fed-bath fermentation with in situ addition of anion-exchange resin significantly helped to enhance the growth of P. acidilactici by reducing the inhibitory effect of lactic acid and thus increasing probiotic production.

Highlights

Lactic acid bacteria (LAB) have recently attracted greater attention for industrial use due to their microorganisms beneficial to human or animals and probiotic properties (Hwang et al 2011)
Increased in initial glucose concentration from 0 to 10 g/L increased viable cell concentration of P. acidilactici by about 14.9 times whilst at glucose concentration of above 10–20 g/L viable cell concentration of P. acidilactici was reduced by about 1.4 times
The final viable cell concentration was further reduced to 8.4 × 104 cfu/mL when 10 g/L of lactic acid was added and no cells were survived when 15 g/L of lactic acid was added to the culture

Summary

Introduction

Lactic acid bacteria (LAB) have recently attracted greater attention for industrial use due to their microorganisms beneficial to human or animals and probiotic properties (Hwang et al 2011). Foods that contain probiotic in an appropriate amount are beneficial to human for instance. High cell density during fermentation is important in order to achieve targeted biomass, lactic acid and other metabolites productivity. Conducive biochemical and biophysical conditions are important for bacteria to grow and express normal metabolic activities. Biophysical conditions such as temperature, pH, redox potential, water activity and the presence of inhibitory compounds gave a broad range of variations among LAB strains. A suitable biochemical condition for LAB to grow can be obtained from nutrients provided by the culture media (Hayek and Ibrahim 2013)

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Conclusion