Bacteria may adhere to and develop biofilm structures onto dairy surfaces trying to protect themselves from adverse conditions such as pasteurization and CIP processes. Thus, biofilms are considered common sources of food contamination with undesirable bacteria. The purpose of this study was to evaluate the diversity of the microbiota attached to stainless steel surfaces in pre-and post-pasteurization pipe lines of a milk-processing plant. Seventy Gram-positive isolates were identified as Enterococcus faecalis (33), Bacillus cereus (26), Staphylococcus hominis (8), Staphylococcus saprophyticus (2), and Staphylococcus epidermidis-Staphylococcus aureus (1) species. Fifty-five Gram-negative isolates were identified to the species Escherichia coli (18), Klebsiella pneumoniae (13), Acinetobacter calcoaceticus (6), Serratia marcescens (6), Enterobacter spp. (5), Pseudomonas aeruginosa (4), Escherichia vulneris (2), and Proteus mirabilis (1). Fifty-five different strains were detected by the RAPD technique. These were subjected to an in vitro assay to evaluate their biofilm-forming capability. E. faecalis (7), A. calcoaceticus (4), K. pneumoniae (3), S. hominis (3), and P. aeruginosa (2) were the species in which more biofilm producer strains were encountered. The adhered microbiota was also assessed by the PCR-DGGE culture-independent technique. This analysis revealed a greater bacterial diversity than that revealed by culturing methods. In this way, in addition to the bacteria detected by culturing, DNA bands belonging to the genera Chrysobacterium and Streptomyces were also identified. This study emphasizes that knowledge of attached Dairy Sci. & Technol. (2016) 96:27-38 DOI 10.1007

Physic cereu DIDOUH N boratoire de M Bacillus ce environmen Bacillus ce microbial a Spores of e spore zeta were invest clear obser stainless st sufficient to surface cha surface of s Key words (TEM). TRODUCTION cillus is ubiqu read through vironments, B countered ba and, 2002; W reus is widely d is occasion choeni and W Corresponding a uthor(s) agree t 0International L 7-65, 14 Janua AJMR2014.6953 r: B094A31501 8 015 n the copyrigh cademicjourn Research co-che us spo assima, CH Microbiologie ereus is an nt. In this stu reus strains adhesion to eleven (11) s potential val tigated by tr rvation of an teel was als o explain the aracters of B spore and ex : Bacterial s N uitously prese h food prod Bacillus is p acteria (Salo Waak et al., 2 reported as r nally an opp ong, 2005

No abstract