An innovative field of research has to do with the microbiological production of potentially functional conjugated fatty acids. Recent studies have pointed to interest in some of these conjugated compounds owing to their antioxidant, anti-carcinogenic potential and, in particular, their effect on reducing body fat.

Kefir is a good substrate for isolating lactic acid bacteria and yeasts that are suitable for converting fatty acids into their conjugated isomers. The aim of the work presented by AZTI-Tecnalia at the II Industrial Microbiology and Microbial Biotechnology Congress of the Spanish Society for Microbiology was to isolate and identify the different micro-organisms present in different kefir samples, in addition to assessing its potential capacity for producing conjugated fatty acids.

It can be concluded from the results obtained that kefir constitutes a good source for obtaining interesting micro-organisms in order to produce potentially functional conjugated fatty acids, although further research still needs to be carried out to analyse its production capacity.

To conduct this study the micro-organisms present in different samples of kefir were isolated and morphologically characterised. This identification was carried out using biochemical tests as well as Molecular Biology techniques.

Bacteria as well as yeasts were isolated. The bacteria found belong to the species Lactobacillus helveticus, Lactobacillus casei, Lactococcus lactis subsp. Lactis, and to the genus Leuconostoc spp. As regards the yeasts, species of the genera Saccharomyces and Kluyveromyces were characterised. Papers have been published citing some of these micro-organisms, like, for example, Lactococcus lactis and Leuconostoc mesenteroides, as producers of conjugated linoleic acid (Sieber et al., 2004; Ogawa et al., 2005).