Production of Bacteriocins by Several Lactic Acid Bacteria and Their Application to Growth Inhibition of Spoilage Bacteria Related to Hiochi

In the food industry, contamination by spoilage microorganisms results in severe safety and economic problems. In the sake-brewing process, spoilaging phenomena caused by several Lactobacillus species, so-called hiochi bacteria, seriously deteriorate the quality of sake, such as lowering the pH, increasing turbidity, and producing offflavors [1,2]. Sake with an ethanol concentration greater than 15% tends to be more resistant to spoilage by microorganisms during storage and aging, but alcoholophilic and alcohol-tolerant hiochi bacteria can grow in such an alcoholic environment and consequently spoil sake. To prevent spoilage by an outbreak of hiochi bacteria in the sake-making process, pasteurization has been carried out at a low temperature (about 65°C) for a short time (2-3 min) or a microfiltration device has been used to remove hiochi bacteria; however, due to incomplete inactivation and insufficient removal of hiochi bacteria, they frequently deteriorate the quality of sake, especially non-pasteurized (fresh) sake, during storage and distribution. Bacteriocins produced by lactic acid bacteria (LAB), which are generally recognized as safe, are of increasing interest because of their antimicrobial spectra with feasible application to foods such as meat and dairy products, fruits, vegetables, cereals, and beverages [3-5]. Since bacteriocins are generally heat-stable, the combination use of bacteriocins with heat treatment is expected to facilitate the complete inactivation of hiochi bacteria and reduce the cost of the heating operation [6,7]; however, since the use of bacteriocins as food additives demands an exhaustive evaluation of their toxicological effects before legal acceptance, bacteriocins are not extensively used in the food industry. Nisin A produced by Lactococcus lactis subsp. lactis, is the only bacteriocin commercially exploited to date, because its use as a biopreservative has been widely investigated in a large variety of fresh and processed foods Production of Bacteriocins by Several Lactic Acid Bacteria and Their Application to Growth Inhibition of Spoilage Bacteria Related to Hiochi