Department of Pathology, College of Medicine, Imam Mohammad Ibn Saud Islamic University (IMSIU), Uthman Ibn Affan Rd, Riyadh, 13317-4233, Saudi Arabia.
BMC Microbiol. 2024 Jul 8;24(1):251. doi: 10.1186/s12866-024-03403-4.
To study the effect of agitation and temperature on biofilm formation (cell aggregates embedded within a self-produced matrix) by pathogenic bacteria isolated from Raw cow milk (RCM).
A 40 RCM samples were gathered from eight dairy farms in Riyadh, Saudi Arabia. After bacterial culturing and isolation, gram staining was performed, and all pathogenic, identified using standard criteria established by Food Standards Australia New Zealand (FSANZ), and non-pathogenic bacteria were identified using VITEK-2 and biochemical assays. To evaluate the effects of temperature and agitation on biofilm formation, isolated pathogenic bacteria were incubated for 24 h under the following conditions: 4 °C with no agitation (0 rpm), 15 °C with no agitation, 30 °C with no agitation, 30 °C with 60 rpm agitation, and 30 °C with 120 rpm agitation. Then, biofilms were measured using a crystal violet assay.
Of the eight farm sites, three exhibited non-pathogenic bacterial contamination in their raw milk samples. Of the total of 40 raw milk samples, 15/40 (37.5%; from five farms) were contaminated with pathogenic bacteria. Overall, 346 bacteria were isolated from the 40 samples, with 329/346 (95.1%) considered as non-pathogenic and 17/346 (4.9%) as pathogenic. Most of the isolated pathogenic bacteria exhibited a significant (p < 0.01) increase in biofilm formation when grown at 30 °C compared to 4 °C and when grown with 120 rpm agitation compared to 0 rpm.
Herein, we highlight the practices of consumers in terms of transporting and storing (temperature and agitation) can significantly impact on the growth of pathogens and biofilm formation in RCM.
研究来自生牛乳（RCM）的致病菌在搅拌和温度影响下生物膜（细胞聚集体嵌入自身产生的基质中）的形成。
从沙特阿拉伯利雅得的 8 个奶牛场收集了 40 个 RCM 样本。经过细菌培养和分离后，进行革兰氏染色，所有致病性细菌根据澳大利亚新西兰食品标准局（FSANZ）制定的标准进行鉴定，非致病性细菌使用 VITEK-2 和生化分析进行鉴定。为了评估温度和搅拌对生物膜形成的影响，将分离的致病菌在以下条件下孵育 24 小时：4°C 无搅拌（0rpm）、15°C 无搅拌、30°C 无搅拌、30°C 60rpm 搅拌和 30°C 120rpm 搅拌。然后，使用结晶紫测定法测量生物膜。
在 8 个农场中，有 3 个农场的生牛乳样本存在非致病性细菌污染。在总共 40 个生牛乳样本中，有 15/40（37.5%；来自 5 个农场）受到致病菌污染。总的来说，从 40 个样本中分离出 346 株细菌，其中 329/346（95.1%）被认为是非致病性的，17/346（4.9%）为致病性的。与 4°C 相比，大多数分离的致病菌在 30°C 下生长时，与 0rpm 相比在 120rpm 搅拌下生长时，生物膜形成明显增加（p<0.01）。
本文强调了消费者在运输和储存（温度和搅拌）方面的做法可能会显著影响 RCM 中病原体的生长和生物膜的形成。
