Antifungal LAB are interesting to prevent food spoilage in fermented food and prolong their shelf life. In this way, chemical preservatives could be avoided and replaced by natural preservatives.

Microbes in the rhizosphere have a suite of extracellular compounds, both primary and secondary, that communicate with other organisms in their immediate environment. Here, we describe a two-way volatile interaction between two widespread and economically important soil-borne pathogens of peanut, Aspergillus flavus and Ralstonia solanacearum, a fungus and bacterium, respectively. In response to A. flavus volatiles, R. solanacearum reduced production of the major virulence factor extracellular polysaccharide (EPS). In parallel, A. flavus responded to R. solanacearum volatiles by reducing conidia production, both on plates and on peanut seeds and by increasing aflatoxin production on peanut. Volatile profiling of these organisms using solid-phase micro-extraction gas chromatography mass spectroscopy (SPME-GCMS) provided a first glimpse at the compounds that may drive these interactions.

Amongst 101 lactic acid bacteria isolated from meat and fish samples, strain CWBI-B1365, identified as Lactobacillus sakei, was found to produce the subclass IIa bacteriocin sakacin G. Partial sequencing of the gene involved in the biosynthetic pathways revealed an unusual gene organisation in that the accessory gene associated with bacteriocin transport did not occur immediately downstream of the gene encoding an ABC transporter, but upstream of the putative immunity gene and encoded on the opposite DNA strand. Sakacin G production was strongly regulated by pH, temperature and the carbon sources used in the growth medium, as well as the concentration of carbon and nitrogen sources. The condition of pH 5.5 and the temperature of 25°C appeared to be optimal for bacteriocin production. The use of sucrose during culturing and the fed batch addition of sucrose and meat extract greatly enhanced bacteriocin production.