Daniel Alexa K, Lee Richard E, Portaels Francoise, Small P L C
Department of Microbiology, University of Tennessee, Knoxville, Tennessee 37996, USA.
Infect Immun. 2004 Jan;72(1):123-32. doi: 10.1128/IAI.72.1.123-132.2004.
Mycobacterium ulcerans is an environmental organism which is responsible for the disease Buruli ulcer, a necrotizing skin disease emerging in west Africa. M. ulcerans produces the polyketide-derived macrolide mycolactone, which is required for the immunosuppression and tissue damage which characterizes Buruli ulcer. We have extracted lipids from the cell envelope and culture filtrate from 52 isolates of Mycobacterium species, analyzed them with thin-layer chromatography, and tested them in a murine fibroblast cell line (L929) cytotoxicity assay to investigate whether these mycobacterial species produce mycolactone. For these studies chloroform-methanol (2:1, vol/vol) extracts were prepared from representative fast- and slow-growing mycobacterial species. Isolates tested included 16 uncharacterized, slow-growing, environmental mycobacterial species isolated from areas in which M. ulcerans infection is endemic. Although several strains of mycobacteria studied produced cytopathic lipids, none of these produced a phenotype on cultured cells consistent with that produced by mycolactone. Two mycobacterial species, M. scrofulaceum and M. kansasii, and eight of the environmental mycobacterial isolates contained cell-associated lipids cytopathic to fibroblasts at concentrations of 33 to 1,000 microg/ml. In contrast, mycolactone produces cytotoxicity at less than 2 ng/ml. Analysis of 16S rRNA sequences from the eight environmental isolates suggests that these are novel mycobacterial species. Results from these studies suggest that, although production of cytopathic lipids is relatively common among mycobacterial species, the production of mycolactone as a cell-associated or secreted molecule appears so far to be restricted to M. ulcerans.
溃疡分枝杆菌是一种环境微生物，可引发布氏溃疡病，这是一种在西非出现的坏死性皮肤疾病。溃疡分枝杆菌产生聚酮衍生的大环内酯类毒素内酯，这是布氏溃疡病免疫抑制和组织损伤所必需的。我们从52株分枝杆菌属菌株的细胞壁和培养滤液中提取脂质，用薄层色谱法进行分析，并在小鼠成纤维细胞系（L929）细胞毒性试验中进行测试，以研究这些分枝杆菌属菌株是否产生毒素内酯。在这些研究中，从代表性的快速生长和缓慢生长的分枝杆菌属菌株中制备了氯仿 - 甲醇（2:1，体积/体积）提取物。测试的菌株包括从溃疡分枝杆菌感染流行地区分离出的16株未鉴定的、生长缓慢的环境分枝杆菌。虽然所研究的几种分枝杆菌菌株产生了细胞病变脂质，但这些菌株在培养细胞上均未产生与毒素内酯一致的表型。两种分枝杆菌，即瘰疬分枝杆菌和堪萨斯分枝杆菌，以及8株环境分枝杆菌分离株在浓度为33至1000微克/毫升时含有对成纤维细胞具有细胞病变作用的细胞相关脂质。相比之下，毒素内酯在浓度低于2纳克/毫升时产生细胞毒性。对8株环境分离株的16S rRNA序列分析表明，这些是新的分枝杆菌物种。这些研究结果表明，虽然细胞病变脂质的产生在分枝杆菌属物种中相对常见，但到目前为止，毒素内酯作为细胞相关或分泌分子的产生似乎仅限于溃疡分枝杆菌。
