Abstract
Fermentation employing lactic acid bacteria (LAB) often suffers end-product inhibition which reduces the cell growth rate and the production of metabolite. The utility of adsorbent resins for in situ lactic acid removal to enhance the cultivation performance of probiotic, Pediococcus acidilactici was studied. Weak base anion-exchange resin, Amberlite IRA 67 gave the highest maximum uptake capacity of lactic acid based on Langmuir adsorption isotherm (0.996 g lactic acid/g wet resin) compared to the other tested anion-exchange resins (Amberlite IRA 410, Amberlite IRA 400, Duolite A7 and Bowex MSA). The application of Amberlite IRA 67 improved the growth of P. acidilactici about 67 times compared to the control fermentation without resin addition. Nevertheless, the in situ addition of dispersed resin in the culture created shear stress by resins collision and caused direct shear force to the cells. The growth of P. acidilactici in the integrated bioreactor-internal column system containing anion-exchange resin was further improved by 1.4 times over that obtained in the bioreactor containing dispersed resin. The improvement of the P. acidilactici growth indicated that extractive fermentation using solid phase is an effective approach for reducing by-product inhibition and increasing product titer.
Highlights
High viable cell density in cultivation of lactic acid bacteria (LAB) is vital to get the valuable biomass to be profitably applied as a probiotic ingredient in various products and proteins sources for human and animal consumptions (Hayek and Ibrahim, 2013; Halim et al, 2017)
Three strong base anion resins (Amberlite IRA 400, Amberlite IRA 410 and Dowex Marathon) and 2-weak base anion resins (Amberlite IRA 67 and Duolite A7) were screened for the highest uptake capacity of lactic acid based on adsorption isotherm
The results of this study indicated that the in situ addition of selected anion exchange resin into the fermentation culture was able to reduce the inhibitory effect of lactic acid on the growth of P. acidilactici
Summary
High viable cell density in cultivation of LAB is vital to get the valuable biomass to be profitably applied as a probiotic ingredient in various products and proteins sources for human and animal consumptions (Hayek and Ibrahim, 2013; Halim et al, 2017). The worldwide demand of lactic acid is estimated to be approximately 130,000 to 150,000 tons per year (Randhawa et al, 2012) and it is expected that the globally usage of lactic acid will increase rapidly in the near future (Wee et al, 2006) These aspects influence the growing interest for more LAB related research and development from researchers and industries (Hayek and Ibrahim, 2013). The transmembrane pH gradient is affected by the undissociated lactic acid that is soluble and the dissociated lactate which is insoluble within the cytoplasmic membrane This reduce the amount of energy available for cell growth. To reduce the inhibitory effect of lactic acid during fermentation process, lactic acid must be removed selectively in situ from the culture (Othman et al, 2017a)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
