Efficient Conversion of Agroindustrial Waste into D(-) Lactic Acid by Lactobacillus delbrueckii Using Fed-Batch Fermentation

Abstract

Purpose. The goal of this paper is to describe the green conversion of agricultural waste products, such as molasses and corn steep liquor, into large amounts of D(-) lactic acid using a facilitated multipulse fed-batch strategy and affordable pH neutralizer. This is a very low-cost process because there is no need for hydrolysis of the waste products. The fed-batch strategy increases lactic acid productivity by avoiding inhibition caused by a high initial substrate concentration, and the selected controlling agent prevents cell stress that could be caused by high osmotic pressure of the culture media. Methods. The effects of different carbon and nitrogen sources on lactic acid production were investigated, and the best concentrations of the medium components were determined. To optimize the culture conditions of the Lactobacillus delbrueckii strain, the effects of pH control, temperature, neutralizing agent, agitation, and inoculum size in batch cultures were investigated. Fed-batch strategies were also studied to improve production and productivity. Result. A high titer of D(-) lactic acid (162g/liter) was achieved after 48 hours of fermentation. Productivity at this point was 3.37 g/L·h. The optimum conditions were a temperature of 39°C, pH 5.5 controlled by the addition of Ca(OH)2, agitation at 150 rpm, and inoculum size of 25% (v/v). Conclusion. The production of high optical purity D(-) lactic acid through L. delbrueckii fermentation with molasses and corn steep liquor is a promising economical alternative process that can be performed on the industrial scale.

Production of lactic acid from whey permeates using lactic acid bacteria isolated from cheese.

“…Enzymes are intensely active at optimum temperature and the enzymatic reaction proceeds at the maximum rates. The optimal temperature for the growth of lactic acid bacteria varies between the genera from 20 to 45°C at 37°C for lactic acid production using L. casei (Wood and Holzapfel, 2012;Beitel et al, 2020). The obtained results are in agreement with the previous data ( Figure 6).…”

“…A pH ranges from 6.0 to7.0 has been reported as optimal for lactic acid production using lactic acid bacteria. Similarly, the pH ranges from 6.0 to 6.5 have been reported as optimal for lactic acid production using L. casei strain (Krischke et al, 1991;Beitel et al, 2020). It is well known that the hydrogen ion concentration of the medium has a great impact on microbial growth.…”

Enhanced Glutamate Synthesis and Export by the Thermotolerant Emerging Industrial Workhorse Bacillus methanolicus in Response to High Osmolarity

“…The thermophilic Gram-positive methylotroph B. methanolicus MGA3 is increasingly recognized as a potential industrial workhorse ( Brautaset et al, 2007 ; Müller et al, 2015a ) for the commodity production of various amino acids, fine chemicals, and recombinant proteins using the readily replenishable and non-food C1 feed-stock methanol ( Brautaset et al, 2003 , 2010 ; Naerdal et al, 2015 , 2017 ; Irla et al, 2016 , 2020 ; Hakvag et al, 2020 ). Keeping in mind that industrial fed-batch production processes will expose the producer microorganisms to high osmolarity surroundings ( Ronsch et al, 2003 ; Zou et al, 2016 ; Borodina, 2019 ; Beitel et al, 2020 ; Habicher et al, 2020 ; Yamakawa et al, 2020 ), we studied how B. methanolicus MGA3 copes physiologically with this challenge and how this constraint on growth could potentially be alleviated.…”

“…Of particular note are osmotic challenges ( Ronsch et al, 2003 ). These are caused through the addition of concentrated feed-solutions to the fermenter, and insufficient mixing of the feed will cause osmotic gradients in the fermenter broth ( Borodina, 2019 ; Beitel et al, 2020 ; Betlej et al, 2020 ; Habicher et al, 2020 ; Yamakawa et al, 2020 ). The high-level accumulation of the desired low-molecular-weight compound(s) in the growth medium is also an issue when methanol is used as the feed.…”

Production of L (+) Lactic Acid by Lactobacillus casei Ke11: Fed Batch Fermentation Strategies

“…Another advantage of the production of lactic acid by fermentation is the possibility of using agro-industrial residues, such as eucalyptus enzymatic hydrolysate [8], orange peel waste hydrolysate [9], microalgae [10], waste cooking oil glycerol [11], cassava bagasse [12] molasses [13,14], food waste [15], hydrolyzed cheese whey [3], brown rice [16],…”