Todorov Svetoslav D, Dicks Leon M T
Department of Microbiology, Stellenbosch University, 7602 Stellenbosch (Matieland), South Africa.
Int J Food Microbiol. 2009 Jun 30;132(2-3):117-26. doi: 10.1016/j.ijfoodmicro.2009.04.010. Epub 2009 Apr 20.
Strain ST44AM, isolated from marula, was identified as Pediococcus pentosaceus based on biochemical tests, sugar fermentation reactions (API 50CHL), PCR with species-specific primers and 16S rDNA sequencing. Strain ST44AM produces a 6.5 kDa class IIa bacteriocin, active against lactic acid bacteria, Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, Listeria innocua, Listeria ivanovii subsp. ivanovii and Listeria monocytogenes. The peptide is inactivated by proteolytic enzymes, but not when treated with alpha-amylase, Triton X-100, Triton X-114, SDS, Tween 20, Tween 80, urea, NaCl and EDTA. No change in activity was recorded after 2 h at pH values between 2.0 and 12.0, and after treatment at 100 degrees C for 120 min or 121 degrees C for 20 min. The mode of activity against L. ivanovii susbp. ivanovii ATCC19119 and Enterococcus faecium HKLHS is bactericidal, resulting in cell lyses and enzyme- and DNA-leakage. No significant differences in cell growth and bacteriocin production were observed when strain ST44AM was cultured in MRS broth at 26 degrees C, 30 degrees C and 37 degrees C for 24 h and tested against the same target strain. L. ivanovii subsp. ivanovii ATCC 19119 and E. faecium HKLHS did, however, differ in sensitivity to bacteriocin ST44AM (3.3x10(6) AU/mL and 2.6x10(4) AU/mL, respectively). Peptide ST44AM adsorbs at high levels (1600 AU/mL) to producer cells. Bacteriocin ST44AM may be a derivative of pediocin PA-1. This is the first report on the presence of P. pentosaceus in marula and a pediocin PA-1 derivative produced by this species. We are also the first to report on the synergetic effect ciprofloxacin has on a pediocin-like bacteriocin.
从马鲁拉果中分离出的ST44AM菌株，通过生化试验、糖发酵反应（API 50CHL）、使用种特异性引物的PCR以及16S rDNA测序，被鉴定为戊糖片球菌。ST44AM菌株产生一种6.5 kDa的IIa类细菌素，对乳酸菌、大肠杆菌、铜绿假单胞菌、肺炎克雷伯菌、无害李斯特菌、伊氏李斯特菌伊凡诺夫亚种和单核细胞增生李斯特菌具有活性。该肽被蛋白水解酶灭活，但用α-淀粉酶、Triton X-100、Triton X-114、SDS、吐温20、吐温80、尿素、NaCl和EDTA处理时不会被灭活。在pH值2.0至12.0之间处理2小时后，以及在100℃处理120分钟或121℃处理20分钟后，活性均未发生变化。对伊氏李斯特菌伊凡诺夫亚种ATCC19119和粪肠球菌HKLHS的作用模式为杀菌，导致细胞裂解以及酶和DNA泄漏。当ST44AM菌株在MRS肉汤中于26℃、30℃和37℃培养24小时并针对相同靶菌株进行测试时，未观察到细胞生长和细菌素产生的显著差异。然而，伊氏李斯特菌伊凡诺夫亚种ATCC 19119和粪肠球菌HKLHS对细菌素ST44AM的敏感性不同（分别为3.3×10⁶ AU/mL和2.6×10⁴ AU/mL）。肽ST44AM以高水平（1600 AU/mL）吸附到产生菌细胞上。细菌素ST44AM可能是片球菌素PA-1的衍生物。这是关于马鲁拉果中存在戊糖片球菌以及该物种产生的片球菌素PA-1衍生物的首次报道。我们也是首个报道环丙沙星对类片球菌素细菌素具有协同作用的研究团队。
