Effect of process parameters on the production of lactic acid bacteria in batch fermentation

The effect of aeration and type of neutralising agent on the growth of lactic acid bacteria, isolated from a typical Italian cheese, was investigated in laboratory fermenters, with the aim of defining process conditions for the production of autochthonous cultures to be used as starters in traditional cheese-making. Batch fermentation trials were carried out using six different bacterial species belonging to the genera Lactobacillus, Lactococcus and Leuconostoc on lactose or glucose based substrates, with sodium-hydroxide (NaOH) or ammonium-hydroxide (NH4OH) as neutralisers and with or without micro-aeration 0.15 vvm. In most cases, optimal conditions for growth were observed in the presence of both ammonium and air supply. The specific growth rate (mu(max)) values required for growth ranged from 0,16 to 0.39 h(-1).