Increased production of bacST4SA by Enterococcus mundtii in an industrial-based medium with pH-control
Thesis (MScEng (Process Engineering))--University of Stellenbosch, 2007.
Lactic acid bacteria (LAB) are producers of bacteriocins, ribosomally synthesized antimicrobial peptides. Bacteriocins are secreted into the surrounding environment where they inhibit growth of other bacteria competing for the same nutrients in a particular environment, usually closely related strains. Some of the bacteriocin-sensitive bacteria include food spoilers and - pathogens, which makes bacteriocins potential natural food preservatives. The need for more natural preservation techniques in the food industry is high: Consumers prefer ready-toeat, minimally processed foods containing no chemical preservatives, but at the same time food spoilage and food-related illnesses are areas of big concern. The antibacterial and antiviral properties of some bacteriocins have also made them suitable for controlling bacterial infections, e.g. as part of pharmaceutical ointments. The increasing rate of resistance against antibiotics by micro-organisms has created a market for alternative treatments for infections. Commercial bacteriocin manufacturing proceeds in controlled fermentations or by extraction from plant material. Enterococcus mundtii ST4SA produces a bacteriocin, bacST4SA, with properties giving it potential for use as a food preservative or as part of a pharmaceutical product. In this study, production of bacST4SA by fermentation of low-cost food-grade growth media, sugarcane molasses, corn steep liquor (CSL) and cheese whey, was considered to increase the economic viability of production for food application. Furthermore, individual de Man Rogosa and Sharpe (MRS) medium components, pH and fed-batch fermentation were evaluated to improve bacST4SA activity...