Characterisation of Thermotolerant Cocci from Indigenous Flora of ‘Leben’ in Algerian Arid Area and DNA Identification of Atypical Lactococcus lactis Strains Farid Bensalah Æ Christine Delorme Æ P. Renault Received: 11 December 2008 / Accepted: 2 April 2009 / Published online: 30 May 2009 Ó Springer Science+Business Media, LLC 2009 Abstract Lactic acid bacteria (LAB) are widely used in food industry and their growth performance is important for the quality of the fermented product. By combining results from conventional isolation methods and molecular investigation of 16S rRNA gene and lactococcal/entero- coccal specific genes, we identify at species level catalase negative gram positive thermoresistant cocci isolated from traditional ‘leben’, a 24-h fermented milk in arid area of west Algeria. Forty strains phenotypically related to cocci LAB were identified as belonging to the species Lacto- coccus lactis ssp. lactis, Enterococcus faecalis, Entero- coccus faecium, and other Enterococcus species. No Streptococcus thermophilus strain was isolated. Ten dif- ferent phenotype groups were recognized, and the species content of these groups were in some cases different from the expected features usually given in genus and species descriptions. In particular, atypical lactococci, able to grow in 6.5% NaCl, at pH 9.5 and showing high resistance to thermal stresses were isolated. Lactococci, but also enterococci isolated from traditional ‘leben’ produced in the desert area, may be therefore of interest in milk fer- mentation. Further studies to assess this source of diversity within the wild microbial population should provide starter new strains for product innovation. Introduction Isolation of Lactococcus lactis ssp. lactis from fermented milk under high-thermal stress has not been reported. Some lactic acid bacteria (LAB) used in the dairy industry, for example, Lactobacillus delbrueckii, Lactobacillus helveti- cus and Streptococcus thermophilus are already known as thermotolerant starter species from their temperature range for growth [5]. During industrial processes changes in temperature may represent an environmental stress to be overcome by starters and non-starters LAB, and studies on adaptation to heat shock have shown the involvement of the chaperon system proteins or the presence of heat stress protein genes (hsp) in various Gram-positive bacteria [2, 26]. However, there is only little knowledge about the biodiversity of thermotolerant LAB in nature, because very few studies focusing on LAB from the standpoint of their thermotolerance have been performed [20, 24]. ‘Leben’, spontaneously traditional fermented milk from Algeria, is produced from raw milks from cows, goats, ewes and camels using centuries old practices. It is a popular and major daily diet in the rural community. Algerians, in general, prefer consuming it with couscous specialty. This product is thus part of world cultural products, and equivalent to several other indigenous fermented milks such as ‘kule naoto’ from Kenya [19], and ‘Raib’ from Morocco [8]. Moreover, these products are also believed to have additional values over those of simple food, and most of African people believe in their therapeutic values towards curing or protection from ailments such as diar- rhoea and constipation. So far, there is limited scientific information to justify these claims [19]. There is an increasing need to select new microbial strains with func- tional properties for commercial production and for improvement of quality and safety of existing traditional F. Bensalah (&) Faculte ´ des Sciences, De ´partement de Biologie, Universite ´ Es-Se ´nia, Oran 31000, Algeria e-mail: bensalahfarid@yahoo.fr C. Delorme Á P. Renault Genetique Microbienne, Institut National de la Recherche Agronomique, Domaine de Vilvert, 78352 Jouy-en-Josas Cedex, France 123 Curr Microbiol (2009) 59:139–146 DOI 10.1007/s00284-009-9411-1