Abstract
At present, De Man, Rogosa and Sharpe (MRS) broth is the medium of choice for promoting bacteriocin production. However, this medium is expensive and not applicable for large-scale production. Therefore, a low-cost and high-efficiency culture medium for bacteriocin Lac-B23 production by Lactobacillus plantarum J23 was developed. First, the effects of the composition of MRS broth on bacteriocin Lac-B23 production and bacterial growth were researched by a one variable at a time approach. Then, a Plackett-Burman design was used to screen significant components for production. Finally, the steepest ascent and central composite designs were used to obtain an optimum medium. The final composition of the modified MRS was much simpler than MRS broth, and the modified MRS contained only glucose, yeast extract, dipotassium phosphate, manganese sulfate monohydrate, Tween 80 and sodium acetate anhydrous. The highest bacteriocin Lac-B23 production reached 2560 activity units (AU)/mL in the modified MRS, which is nine times higher than that in MRS broth (280 AU/mL). Meanwhile, the cost per liter of the modified MRS (8.56 Ren Min Bi (RMB)/L) is 34.70% the cost of MRS broth (13.11 RMB/L), and the cost per arbitrary units of bacteriocin Lac-B23 in the modified MRS is approximately fourteen times more convenient (3.34 RMB/106 AU) than in the MRS broth (46.82 RMB/106 AU).
Highlights
Bacteriocins from lactic acid bacteria are bioactive peptides or proteins with antimicrobial activity against different species of Gram-negative and Gram-positive bacteria [1,2,3,4]
Of bacteriocin Lac-B23 was observed when L. plantarum J23 was grown in a medium with 10 g/L yeast extract as the only nitrogen source
Glucose acts as an inducer and regulates the expression of the genes encoding bacteriocin Lac-B23
Summary
Bacteriocins from lactic acid bacteria are bioactive peptides or proteins with antimicrobial activity against different species of Gram-negative and Gram-positive bacteria [1,2,3,4]. Bacteriocins of lactic acid bacteria have been used widely in the field of food preservation as natural food preservatives [5,6]. Only a few bacteriocins from lactic acid bacteria, such as pediocin and nisin, have been used in commercial applications due to three main reasons: (1) high fermentation costs and low production levels, (2) complex extraction and purification processes and (3) the lack of safety evaluations. High fermentation costs and low production levels are the biggest bottleneck in the industrial mass production of bacteriocins [7,8,9]. MRS broth (De Man, Rogosa and Sharpe) is regarded as the beneficial medium for the growth of enterococcus, Lactobacillus and some bacteriocins synthesis [10,11,12]. The components of MRS broth are complex and Biology 2020, 9, 171; doi:10.3390/biology9070171 www.mdpi.com/journal/biology
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