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首页> 外文期刊>Food Control >Safety aspects, genetic diversity and technological characterisation of wild-type Streptococcus thermophilus strains isolated from north Italian traditional cheeses.
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Safety aspects, genetic diversity and technological characterisation of wild-type Streptococcus thermophilus strains isolated from north Italian traditional cheeses.

机译：从意大利北部传统奶酪中分离的野生型嗜热链球菌嗜热菌的安全性，遗传多样性和技术表征。

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Antibiotic susceptibility, antimicrobial activity, genotypic and technological properties of 52 Streptococcus thermophilus isolates, collected from four north Italian traditional cheeses, was investigated. RAPD-PCR, was used to study genetic variability and distinguish closely related strains; the results showed a high degree of heterogeneity among isolates. With regard to technological properties, after 6 h of incubation in milk 25% of the streptococcal strains could be defined as fast acid producers, while after 24 h the majority of isolates (79%) displayed only weak acidification activity. Reduction activity was generally low; in fact, none of these S. thermophilus strains showed a Eh < --102 mV). All the studied S. thermophilus were susceptible to ciprofloxacin, levofloxacin, penicillin G, ampicillin, mupirocin, nitrofurantoin, quinupristin/dalfopristin and rifampicin. Nine isolates were classified as resistant to tetracycline, 6 to streptomycin, 5 to oxacillin, 3 to erytromycin, 3 to vancomycin and only one to chloramphenicol. PCR-based detection did not identify any of the common genetic determinants for vancomycin (vanA, vanB, vanC1, vanC2, vanC3, vanD, vanE, vanG) or erythromycin (ermB and ermC). The genetic basis of the tetracycline resistance phenotype in these strains was linked to tetS-tetL genes (8 isolates) or the tetM gene (1 isolate), and the integrase element int of the Tn916/Tn1545 family of transposons was negative. Four strains were able to produce antimicrobial compounds against Clostridium tyrobutyricum. The study provides new evidence of the resistance of S. thermophilus to antimicrobial agents, confirming the importance of including an accurate safety assessment of phenotypic/biotechnological data when carrying out strain selection for dairy applications
机译：研究了从意大利北部的四种传统奶酪中收集的52种嗜热链球菌的抗生素敏感性，抗菌活性，基因型和技术特性。 RAPD-PCR用于研究遗传变异和区分密切相关的菌株。结果表明，分离株之间存在高度异质性。关于技术特性，在牛奶中孵育6小时后，可将25％的链球菌菌株定义为快速产酸剂，而在24小时后，大多数分离株（79％）仅显示弱酸化活性。还原活性通常较低;实际上，这些嗜热链球菌均未显示Eh <--102 mV。所有研究过的嗜热链球菌均对环丙沙星，左氧氟沙星，青霉素G，氨苄西林，莫匹罗星，硝基呋喃妥因，奎奴普丁/达福普汀和利福平敏感。九个分离株被分类为对四环素具有抗性，对链霉素具有6种抗性，对奥沙西林具有5种抗性，对红霉素具有3种抗性，对万古霉素具有3种抗性，而对氯霉素仅一种抗性。基于PCR的检测未发现万古霉素的任何常见遗传决定因素（ van A， van B， van C1， van C2， van C3， van D， van E， van G）或红霉素（< i> erm B和 erm C）。这些菌株中四环素抗性表型的遗传基础与 tet S- tet L基因（8个分离株）或 tet M基因相关（1个分离株），转座子Tn 916 / Tn 1545 家族的整合素int为阴性。四种菌株能够产生针对酪酪酸梭菌的抗菌化合物。该研究提供了抗iS的新证据。嗜热菌抗微生物剂，证实了在为乳制品应用进行菌株选择时，包括对表型/生物技术数据进行准确安全评估的重要性

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