a b s t r a c tThe aim of the present study was to investigate the biochemical characteristics, extracellular enzyme production and enterotoxigenic genes contents of 6 Bacillus cereus and 22 Bacillus thuringiensis strains, isolated from 100 cheese samples in Turkey. Crystal morphologies of B. thuringiensis strains were found either spherical (n = 12) or spherical and irregular-shaped (n = 10) by phase contrast microscopy. B. cereus and B. thuringiensis strains were found to produce extracellular enzymes, respectively: gelatinase (83% and 91%), DNase (83% and 77%), lecithinase (83% and 95%), protease on skim milk agar (100% and 100%), protease on milk agar (100% and 91%), protease on casein agar (83% and 77%), xylanase (100% and 45%), and cellulase (0% and 41%), and amylase (83% and 27%). All of the strains, except for Bt-D1, hydrolyzed Tween 20 (96%), but not Tween 80 or tributyrin. Pectinolytic activity was obtained to be the least frequent (4%). PCR analysis showed that all strains contained nheA, nheB, nheC and hblD genes. The hblA and hblC genes were present in 2 and 4 of B. thuringiensis strains, respectively. The bceT gene was detected in 1 B. cereus and 9 B. thuringiensis strains. The entFM gene was detected more frequently in B. thuringiensis (82%) than in B. cereus strains (50%). To our knowledge, this is the first report about the isolation and identification of enterotoxigenic B. cereus and B. thuringiensis strains from cheese samples in Turkey.

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Chemical compounds studied in this article: Grape seed extract (proanthocyanidins) (PubChem CID: 108065) gallic acid (PubChem CID: 370) disodium carbonate (PubChem CID: 10340) sodium acetate trihydrate (PubChem CID: 23665405) 2,4,6-tripyridyl-s-triazine (PubChem CID: 77258) iron chloride (PubChem CID: 24380) a b s t r a c tThe present study evaluated the antimicrobial activity of grape seed extract (GSE) against Alicyclobacillus acidoterrestris vegetative cells and spores in apple juice (pH 3.82, Brix 11.3) during storage at 37 C. After 336 h, reductions in the cell numbers were 3.14, 3.55, 3.8, 4.1, and 4.63 log CFU/mL in the apple juice with 0.23, 0.45, 0.9, 1.8, and 3.6% of GSE, respectively. The Weibull was found to be the best fitted model for cell inactivation kinetics (R 2 > 0.988). Moreover, the spores produced on different sporulation media (potato dextrose agar, malt extract agar, Bacillus acidoterrestris agar, and Bacillus acidocaldarius agar) were treated with GSE (0e1.9%, v/v). While control spores in apple juice without GSE increased by 2.2e2.6 log CFU/mL within the first 48 h, 0.9% and 1.8% of GSE inhibited the growth from all spore suspensions. Finally, scanning electron microscopy (SEM) indicated that the main target of the GSE may be the membrane of A. acidoterrestris cells leading to leakage of cellular constituents and may prevent the development of spores into vegetative cells. This study highlights the potential use of the by-products of the fruit juice/ beverage industry as natural antimicrobials to inhibit the growth of A. acidoterrestris.

5 log CFU/mL) in apple juice (pH 3.82, Brix 11.3) during storage at 37 C. After 240 h, the cell counts were reduced from the initial log count (CFU/mL) by 2. 84, 3.26, 3.32, 3.46 and 3.56 in the apple juice with PE at the concentrations of 2.5, 5, 10, 20 and 40 mg/mL, respectively. On the other hand, counts of the control reached 7.36 log CFU/mL after 24 h. The Weibull model satisfactorily described the survival curves of cell inactivation kinetics (R 2 > 0.983). While the growth of all spores obtained from different sporulation media (potato dextrose agar, malt extract agar, Bacillus acidoterrestris agar, and Bacillus acidocaldarius agar) was inhibited in the apple juice with PE (2.5e40 mg/mL), the control spores increased by 1.9e2.2 log CFU/mL after 336 h. Based on the scanning electron microscopy (SEM) imaging, vegetative cells indicated substantial damage and spore germination was inhibited in the apple juice with PE. The results showed that PE can have possible uses as a natural antimicrobial to control the growth of A. acidoterrestris vegetative cells and spore germination in the apple juice.

Water plays an important role in the transmission of Arcobacter spp. to animals and humans. The aim of this study was to isolate and characterize Arcobacter spp. from 115 different water samples (66 sewage, 25 rivers, 16 spring water, and 8 drinking water) in Izmir, Turkey. In total, 41 samples (35.7 %) were found positive for Arcobacter spp. by the genus-specific PCR. Arcobacter butzleri was detected in 39 out of 115 samples (33.9 %) including 24 sewage, 13 rivers, and 2 spring water. The remaining Arcobacter spp. (n = 2) isolates could not be identified by m-PCR and 16S rRNA gene sequencing. Based on the phenotypic characterization, most of the Arcobacter species (87.8 %) indicated weak catalase activity. In addition, there were differences in phenotypic patterns among isolated species during growth at 37°C under microaerobic and aerobic conditions, in the presence of 2 % (39/41) and 3.5 % (32/41) NaCl and 0.04 % TTC (39/41) and on MacConkey agar (38/41). The results of this study indicated that environmental water samples are common sources for Arcobacter spp. Therefore, effective control measures should be taken to protect human health.

Alicyclobacillus acidoterrestris is a spoilage bacterium in fruit juices leading to high economic losses. The present study evaluated the effect of sporulation medium on the thermal inactivation kinetics of A. acidoterrestris DSM 3922 spores in apple juice (pH 3.82 ± 0.01; 11.3 ± 0.1°Brix). Bacillus acidocaldarius agar (BAA), Bacillus acidoterrestris agar (BATA), malt extract agar (MEA), potato dextrose agar (PDA) and B. acidoterrestris broth (BATB) were used for sporulation. Inactivation kinetic parameters at 85, 87.5 and 90°C were obtained using the log-linear model. The decimal reduction times at 85°C (D 85°C ) were 41.7, 57.6, 76.8, 76.8 and 67.2 min; D 87.5°C -values were 22.4, 26.7, 32.9, 31.5, and 32.9 min; and D 90°C -values were 11.6, 9.9, 14.7, 11.9 and 14.1 min for spores produced on PDA, MEA, BATA, BAA and BATB, respectively. The estimated z-values were 9.05, 6.60, 6.96, 6.15, and 7.46, respectively. The present study suggests that the sporulation medium affects the wet-heat resistance of A. acidoterrestris DSM 3922 spores. Also, the dipicolinic acid content (DPA) was found highest in heat resistant spores formed on mineral containing media. After wet-heat treatment, loss of internal volume due to the release of DPA from spore core was observed by scanning electron microscopy. Since, there is no standardized media for the sporulation of A. acidoterrestris, the results obtained from this study might be useful to determine and compare the thermal resistance characteristics of A. acidoterrestris spores in fruit juices.

Arcobacters are food and waterborne pathogens associated with human and animal infections. The objective of the present study was to investigate the prevalence and diversity of <em>Arcobacter</em> spp. in commercially sold chicken meat in İzmir region of Turkey. For this purpose, 100 samples including legs (n=40), 17 chicken quarters (n=17), drumstickers (n=16), breasts (n=11), wings (n=10), and carcasses (n=6) were collected from different retail markets. A total of 65 isolates were confirmed as <em>Arcobacter</em> spp. from 55 samples by genus-specific polymerase chain reaction (PCR). The prevalence of <em>Arcobacter</em> spp. was 32.5, 81.3, 64.7, 72.7, 83.3, and 50% for legs, drumstickers, chicken quarters, breasts, carcasses and wings, respectively. Based on the multiplex-PCR, most of the isolates were identified as <em>A. butzleri</em> (n=45, 80%), followed by <em>A. cryaerophilus</em> (n=2, 3.6%), <em>A. skirrowii</em> (n=1, 1.8%) and 17 isolates (30.9%) could not be identified at the species level.

Listeria monocytogenes is one of the most important foodborne pathogens and is a causal agent of listeriosis in humans and animals. The aim of this study was to determine the prevalence, serogroups, antibiotic susceptibility, virulence factor genes, and genetic relatedness of L. monocytogenes strains isolated from 500 poultry samples in Turkey. The isolation sources of 103 L. monocytogenes strains were retail markets (n = 100) and slaughterhouses (n = 3). L. monocytogenes strains were identified as serogroups 1/2a-3a (75.7%, lineage I), 1/2c-3c (14.56%, lineage I), 1/2b-3b-7 (5.82%, lineage II), 4a-4c (2.91%, lineage III), and 4b-4d-4e (0.97%, lineage III). Most of the L. monocytogenes strains (93.2%) were susceptible to the antibiotics tested. PCR analysis indicated that the majority of the strains (95% to 100%) contained most of the virulence genes (hylA, plcA, plcB, prfA, mpl, actA, dltA, fri, flaA inlA, inlC, and inlJ). Pulsed-field gel electrophoresis (PFGE) demonstrated that there were 18 pulsotypes grouped at a similarity of > 90% among the strains. These results indicate that it is necessary to prevent the presence of L. monocytogenes in the poultry-processing environments to help prevent outbreaks of listeriosis and protect public health.