冷冻鸡肉中耐冷菌的分布及对优势菌的控制

本项目以市售的冷冻鸡腿、冷冻鸡翅和冷冻鸡爪为研究对象,评价冷冻鸡肉的微生物污染,分析其中耐冷细菌分布的多样性。结果表明,冷冻鸡爪的微生物污染最严重,可达10~5 CFU/g。从三种鸡肉样品中共分离得到100株耐冷细菌,其中假单胞菌属(Pseudomonas sp.)占49%,嗜冷杆菌属(Psychrobacter sp.)和沙雷氏菌属(Serratia sp.)分别占13%和12%。在假单胞菌属中,莓实假单胞菌(Pseudomonasfragi)达到了61%。对冷冻鸡爪中分离得到的30株细菌,通过构建系统发育树,确定分类地位。进一步选择了一株莓实假单胞菌(P.fragi 30-1),研究其生长特性,并对其进行抑菌试验。结果证明P.fragi 30-1具有较强的耐冷性,最大能耐受2.5%NaCl,适宜在p H 6~8的环境中生长。氯霉素、罗红霉素以及茶多酚对P.fragi 30-1均有较好的抑菌作用,最小抑菌浓度(MIC)分别为0.31 mg/mL,0.62 mg/mL和0.62 mg/mL。本研究为了解冷冻鸡肉的安全性提供基础,也为P.fragi的污染控制提供方向。

Distribution of Cold-resistant Bacteria in Frozen Chicken and the Control of Dominant Bacteria

This project used commercially available frozen chicken leg, frozen chicken wing and frozen chicken feet as the research objects to evaluate the microbial contamination in frozen chicken meat and analyze the diversity of cold-resistant bacteria distribution. The results showed that the microbial contamination of frozen chicken feet was the most serious (up to 105 CFU/g). A total of 100 cold-tolerant bacteria were isolated from three types of chicken meat samples, of which Pseudomonas accounted for 49%, Psychrobacter and Serratia accounted for 13% and 12%, respectively. In the genus Pseudomonas, sixty-one percent of Pseudomonas were identified as Pseudomonas fragi. A phylogenetic tree was built for the 30 strains isolated from frozen chicken feet to estimate their phylogenetic positions. A P. fragi 30-1 strain was further selected to study its growth characteristics and subjected to the antibacterial test. The results showed that P. fragi 30-1 had strong cold resistance, could withstand a maximum of 2.5% NaCl, and is suitable for growth in a pH 6~8 environment. Chloramphenicol, roxithromycin, and tea polyphenols had good antibacterial activities against P. fragi 30-1, and the minimum inhibitory concentrations (MICs) were 0.31 mg/mL, 0.62 mg/mL and 0.62 mg/mL, respectively. This study provided a basis for understanding the safety of frozen chicken and also insights into the control of P. fragi contamination.