Proceedings of the XLVI Italian Society of Agricultural Genetics - SIGA Annual Congress

Giardini Naxos, Italy - 18/21 September, 2002

ISBN 88-900622-3-1

Poster Abstract - 3.01

MOLECULAR IDENTIFICATION AND CHARACTERIZATION OF ACID LACTIC BACTERIA ISOLATED FROM SICILIAN SOURDOUGHS

RANDAZZO C., RESTUCCIA C.

DOFATA – Dipartimento di Orto-Floro-Arboricoltura e Tecnologie Agroalimentari – Sezione Tecnologie Agroalimentari, Università degli Studi di Catania, Via Santa Sofia 98, 95123 Catania

sourdough, lactic acid bacteria, PCR/RFLP of 16S rDNA

Sourdough has been the only starter used in bread making for ages without any knowledges on the presence and role of microorganisms. Sourdough is a complex biological system which includes a varied microbial population mainly represented by yeasts (S. cerevisiae, S. exiguus, Torulaspora delbrueckii and Candida spp, etc) and by homofermentative and heterofermentative lactic acid bacteria (Lactobacillus brevis, Lb. plantarum, Lb. sake, Lb. sanfranciscensis). This indigenous microbial community is involved in producing the typical organoleptic and structural traits of bread. To study the nature of the sourdough microbial communities, several samples of Sicilian sourdough, mainly produced from Triticum durum wheat, were collected from different family-run bakeries.

In the present study the acid lactic bacteria of Sicilian sourdoughs were investigated by a combination of classical techniques and Restriction Fragments Length Polymorphism (RFLP) analysis of the 16S rDNA. Bacterial isolates were considered as belonging to the genus Lactobacillus based on their positive Gram reaction, non-motility, absence of catalase activity and spore formation, and their rod shape. The RFLP results showed a remarkable bacterial heterogeneity. Dominant strains were identified by partial sequencing of the 16S rDNA as belonging to Lb. sanfranciscensis, Lb. paraplantarum and Lb. pentosus species.

The dominance of Lb. sanfranciscensis strains has been confirmed, besides, by the high number of isolates in SDB selective medium. Identification of microbial community and their dynamism represent an important pre-requisite for microbiological quality and safety of artisanal fermented foods and may contribute to the development of new multiple starters for baking.