Institute of Food, Nutrition and Human Health, Massey University, Private Bag 11222, Palmerston North, New Zealand.
Int J Food Microbiol. 2012 Jun 15;157(1):28-34. doi: 10.1016/j.ijfoodmicro.2012.04.008. Epub 2012 Apr 20.
In this study, six bacterial isolates that produced thermo-resistant enzymes isolated from the internal surfaces of raw milk tankers were evaluated for their ability to produce proteolysis within either single culture biofilms or co-culture biofilms. Biofilms were formed in an in vitro model system that simulated the upper internal surface of a raw milk tanker during a typical summer's day of milk collection in New Zealand. The bacterial isolates were further evaluated for their ability to form biofilms at 25, 30 and 37°C. Mutual and competitive effects were observed in some of the co-culture biofilms, with all isolates being able to form biofilms in either single culture or co-culture at the three temperatures. The proteolysis was also evaluated in both biofilms and corresponding planktonic cultures. The proteolysis per cell decreased as the temperature of incubation (20-37°C) increased. Furthermore, mutualistic interactions in terms of proteolysis were observed when cultures were grown as co-culture biofilms. This is the first study to show that proteolytic enzymes can be produced in biofilms on the internal surfaces of raw milk tankers. This has important implications for the cleaning and the temperature control of raw milk transport tankers.
在这项研究中，评估了从生奶罐内部表面分离出的 6 株产耐热酶的细菌分离株，以评估它们在单一培养物生物膜或共培养物生物膜中产生蛋白水解的能力。生物膜是在体外模型系统中形成的，该系统模拟了新西兰夏季典型的一天中牛奶收集过程中生奶罐的上内部表面。进一步评估了细菌分离株在 25、30 和 37°C 下形成生物膜的能力。在一些共培养物生物膜中观察到了相互和竞争作用，所有分离株都能够在三种温度下的单一培养物或共培养物中形成生物膜。还评估了生物膜和相应浮游培养物中的蛋白水解。随着孵育温度（20-37°C）的升高，每个细胞的蛋白水解减少。此外，当培养物作为共培养物生物膜生长时，观察到蛋白水解方面的共生相互作用。这是首次表明蛋白酶可以在生奶罐内部表面的生物膜中产生的研究。这对生奶运输罐的清洁和温度控制具有重要意义。
