Université Abou Bekr Belkaid Tlemcen, Algeria; Laboratoire de Microbiologie Appliqué à l'Agroalimentaire au Biomédical et à l'Environnement, 13000 Tlemcen, Algeria.
Université Abou Bekr Belkaid Tlemcen, Algeria; Laboratoire de Microbiologie Appliqué à l'Agroalimentaire au Biomédical et à l'Environnement, 13000 Tlemcen, Algeria; Université Hassiba Benbouali Chlef, Algeria.
Int J Food Microbiol. 2023 Dec 16;407:110389. doi: 10.1016/j.ijfoodmicro.2023.110389. Epub 2023 Sep 9.
Bacterial biofilm is a major concern of dairy industry due to its association with milk contamination and its derived products. Algerian pasteurized milk shelf-life does not exceed one day, which may reflect the high level of contamination of this product and presence of extracellular enzymes such as lipases and proteases. This work aimed to investigate the microbial biodiversity in milk-processing surfaces of a dairy plant in Algeria. Therefore, stainless steel cylinders were placed in piping system of the dairy system before and after pasteurization of the milk, being removed after 7 days, for biofilm maturation and microorganism isolation and identification by mass spectrometry. Fifty-nine Gram-positive isolates were identified, namely Bacillus altitudinis, Bacillus cereus, Bacillus pumilus, Bacillus subtilis, Bacillus weithenstephanensis, Enterococcus casseliflavus, Enterococcus faecium, and Staphylococcus epidermidis. In addition, twenty-four Gram-negative isolates were identified, namely Acinetobacter schindleri Enterobacter cloacae, Enterobacter xiangfangensis, Leclercia adecarboxylata, and Raoultella ornithinolytica. Bacterial isolates showed ability for production of extracellular enzymes, being 49 % capable of both proteolytic and lipolytic activities. Milk isolates were tested for the ability to form biofilms on stainless steel. The cell numbers recovered on plate count agar plates from stainless steel biofilms ranged from 3.52 to 6.92 log10 CFU/cm, being the maximum number detected for Enterococcus casseliflavus. Bacterial isolates showed intermediate and/or resistant profiles to multiple antibiotics. Resistance to amoxicillin, cefoxitin and/or erythromycin was commonly found among the bacterial isolates.
由于与牛奶污染及其衍生产品有关，细菌生物膜是乳品行业的主要关注点。阿尔及利亚巴氏消毒牛奶的保质期不超过一天，这可能反映出该产品的污染水平很高，并且存在细胞外酶，如脂肪酶和蛋白酶。本工作旨在研究阿尔及利亚一家乳品厂牛奶加工表面的微生物多样性。因此，在牛奶巴氏消毒前后，将不锈钢圆筒放置在乳品系统的管道系统中，在 7 天后取出，以成熟生物膜并通过质谱法分离和鉴定微生物。鉴定出 59 株革兰氏阳性菌，分别为高山芽孢杆菌、蜡样芽孢杆菌、解淀粉芽孢杆菌、枯草芽孢杆菌、韦氏芽孢杆菌、粪肠球菌、屎肠球菌和表皮葡萄球菌。此外，还鉴定出 24 株革兰氏阴性菌，分别为施氏假单胞菌、阴沟肠杆菌、襄汾肠杆菌、产甲酸莱氏菌和鸟氨酸罗伊氏菌。细菌分离株表现出产生细胞外酶的能力，有 49%的分离株同时具有蛋白水解和脂肪水解活性。对不锈钢上形成生物膜的能力进行了牛奶分离株的测试。从不锈钢生物膜平板计数琼脂平板上回收的细胞数量在 3.52 到 6.92 log10 CFU/cm 之间，肠球菌分离株的数量最多。细菌分离株对多种抗生素表现出中间和/或耐药谱。细菌分离株中常见对阿莫西林、头孢西丁和/或红霉素的耐药性。
