Potisap Chotima, Khan Md Abdul Wadud, Boonmee Atcha, Rodrigues Jorge L M, Wongratanacheewin Surasakdi, Sermswan Rasana W
Melioidosis Research Center and Department of Biochemistry, Faculty of Medicine, Khon Kaen University, 123 Mitraparb Rd, Muang District, Khon Kaen Province, 40002, Thailand.
Department of Biology, University of Texas at Arlington, Arlington, TX, USA.
AMB Express. 2018 Aug 24;8(1):136. doi: 10.1186/s13568-018-0663-7.
Burkholderia pseudomallei is a Gram-negative bacterium found in soil and the causative agent of a severe disease in humans and animals known as melioidosis. It is intrinsically resistant to many antibiotics and has been reported resistant to the drugs of choice; ceftazidime. Microbial communities in soil in the presence and absence of B. pseudomallei were investigated using metagenomics approach. The variation in bacterial species diversity was significantly higher in soil samples without B. pseudomallei. Abundances of phyla Actinobacteria and Firmicutes were found significantly higher in B. pseudomallei-negative soils. Bacillus amyloliquefaciens KKU1 in phylum Firmicutes was discovered from negative soil and its secondary metabolites could inhibit clinical, environmental and drug resistant isolates of B. pseudomallei, together with some pathogenic Gram-negative but not Gram-positive bacteria. The antimicrobial activity from KKU 1 against B. pseudomallei was abolished when treated with proteinase K, stable in a wide range of pH and remained active after heating at 100 °C for 15 min. Precipitated proteins from KKU1 were demonstrated to cause lysis and corrugated surfaces of B. pseudomallei. The minimum inhibitory concentrations and minimum bactericidal concentrations of the precipitated proteins from KKU1 against B. pseudomallei were 0.97 μg/ml and 3.9 μg/ml. Interestingly, Native SDS-PAGE showed small active compounds of less than 6 kDa, along with other information collectively suggesting the properties of antimicrobial peptides. For the first time, culture-independent information in melioidosis endemic area could lead to a suspected source of metabolites that may help defense against B. pseudomallei and other pathogenic Gram-negative bacteria.
类鼻疽伯克霍尔德菌是一种存在于土壤中的革兰氏阴性菌，是人类和动物严重疾病类鼻疽的病原体。它对多种抗生素具有内在抗性，并且已有报道称其对首选药物头孢他啶耐药。采用宏基因组学方法研究了存在和不存在类鼻疽伯克霍尔德菌的土壤中的微生物群落。在没有类鼻疽伯克霍尔德菌的土壤样本中，细菌物种多样性的变化显著更高。发现放线菌门和厚壁菌门在类鼻疽伯克霍尔德菌阴性土壤中的丰度显著更高。从阴性土壤中发现了厚壁菌门中的解淀粉芽孢杆菌KKU1，其次生代谢产物可以抑制类鼻疽伯克霍尔德菌的临床、环境和耐药菌株，以及一些致病性革兰氏阴性菌，但不包括革兰氏阳性菌。用蛋白酶K处理后，KKU 1对类鼻疽伯克霍尔德菌的抗菌活性被消除，在广泛的pH范围内稳定，在100℃加热15分钟后仍保持活性。来自KKU1的沉淀蛋白被证明可导致类鼻疽伯克霍尔德菌裂解并使其表面起皱。来自KKU1的沉淀蛋白对类鼻疽伯克霍尔德菌的最低抑菌浓度和最低杀菌浓度分别为0.97μg/ml和3.9μg/ml。有趣的是，非变性十二烷基硫酸钠聚丙烯酰胺凝胶电泳显示活性小分子化合物分子量小于6 kDa，其他信息共同表明其具有抗菌肽的特性。首次在类鼻疽流行地区获得的非培养信息可能会找到一种潜在的代谢物来源，有助于抵御类鼻疽伯克霍尔德菌和其他致病性革兰氏阴性菌。
