ORIGINAL ARTICLE Changes in bacterial populations in refrigerated raw milk collected from a semi-arid area of Algeria Abdelhafid Boubendir 1 & Diana Isabella Serrazanetti 2 & Mohamed Abdelhafid Hamidechi 3 & Lucia Vannini 2,4 & Maria Elisabetta Guerzoni 4 Received: 2 July 2015 /Accepted: 28 September 2015 # Springer-Verlag Berlin Heidelberg and the University of Milan 2015 Abstract Most of the studies on milk microbiota have been performed on cows’ milk from animals reared in tem- perate and humid areas. In this work, changes in the bac- terial consortium of refrigerated raw milk collected from cows grazed in a semi-arid area of Algeria were studied during 21 days of refrigerated storage. Twenty bacterial morpho-physiotypes were selected among 150 isolates from milk at different times over storage and identified by partial 16S rRNA gene sequencing. The dominant bacterial popula- tions were characterized by a few species. Stenotrophomonas rhizophila, S. maltophilia and Chryseobacterium indologenes were predominant during the first 7 days, Lactobacillus pentosus and L. plantarum were isolated only after the 10th day, while Acinetobacter spp. was isolated at the end of stor- age. Compared to the current literature on milk from temper- ate zones, sluggish and incomplete microbial growth was ob- served with a long incubation phase ranging from 6.7 to 10.5 days and a maximum growth not exceeding 5.3 log colony-forming units (CFU)·mL -1 . The composition of milk microbiota and its evolution over refrigeration suggest a bio- geographical characterization due to environmental factors. In particular, the possible presence of antimicrobial molecules coming from plants grazed in the semi-arid zone around the farm may account for the presence of selected microbial spe- cies and the extended milk shelf-life. Despite this being a preliminary work, these results encourage the use of arid herbs in animal feed and motivate scientists to focus their efforts on the study of biochemical composition of plants from arid areas and their antimicrobial activity. Keywords Raw cows’ milk . Microbiota . Sluggish growth dynamic . Refrigerated storage . Semi-arid area Introduction The potential content and relative ratios of the basic nutrients, lipids and proteins in milk are genetically determined. However, environmental, nutritional and physiological factors greatly influence milk composition and flavour (Morand-Fehr et al. 2007). As suggested by recent studies, the presence of botanically diverse plant species in pastures can significantly affect the occurrence and content of functional molecules, and namely polyunsaturated fatty acids, in milk (Rubino et al. 2006). Numerous studies have shown the beneficial effects of herbs and spices on animal feed intake, immune functions and health as well as on rumen fermentation and productivity (Frankič et al. 2006). Moreover, it has been reported that the intake of some plants in arid zones results in the important healthy attributes of camel milk and, namely, antidiabetic ac- tion (Agrawal et al. 2007). Raw cows’ milk and dairy products are characterized by a wide microbial biodiversity and more than 150 species have been identified by means of the combination of culture depen- dent and independent methods (Delbès et al. 2007; Vithanage * Abdelhafid Boubendir a.hafid.bio@gmail.com 1 Department of Natural Sciences and Life, University Centre Abdelhafid Boussouf, RP.26, Mila 43000, Algeria 2 Inter-departmental Centre for Industrial Agri-Food Research, Piazza Goidanich 60, 47521 Cesena, Italy 3 Faculty of Natural Sciences and Life, University Mentouri, Constantine 25000, Algeria 4 Department of Agricultural and Food Sciences, Alma Mater Studiorum, University of Bologna, Viale Fanin 46, 40127 Bologna, Italy Ann Microbiol DOI 10.1007/s13213-015-1163-5