Laboratory of Applied Micro and Nanotechnology (LAMINATE), National Veterinary Institute (VET), Technical University of Denmark (DTU), Hangøvej 2, DK-8200 Aarhus N, Denmark.
Environ Microbiol. 2012 Aug;14(8):2034-47. doi: 10.1111/j.1462-2920.2011.02655.x. Epub 2011 Dec 19.
Campylobacter jejuni is a major cause of infectious diarrhoea worldwide but relatively little is known about its ecology. In this study, we examined its interactions with Acanthamoeba castellanii, a protozoan suspected to serve as a reservoir for bacterial pathogens. We observed rapid degradation of intracellular C.jejuni in A.castellanii 5 h post gentamicin treatment at 25°C. Conversely, we found that A.castellanii promoted the extracellular growth of C.jejuni in co-cultures at 37°C in aerobic conditions. This growth-promoting effect did not require amoebae - bacteria contact. The growth rates observed with or without contact with amoeba were similar to those observed when C.jejuni was grown in microaerophilic conditions. Preconditioned media prepared with live or dead amoebae cultivated with or without C.jejuni did not promote the growth of C.jejuni in aerobic conditions. Interestingly, the dissolved oxygen levels of co-cultures with or without amoebae - bacteria contact were much lower than those observed with culture media or with C.jejuni alone incubated in aerobic conditions, and were comparable with levels obtained after 24 h of growth of C.jejuni under microaerophilic conditions. Our studies identified the depletion of dissolved oxygen by A.castellanii as the major contributor for the observed amoeba-mediated growth enhancement.
空肠弯曲菌是全球范围内引起感染性腹泻的主要原因之一，但人们对其生态学知之甚少。在本研究中，我们研究了它与棘阿米巴属（一种被怀疑是细菌病原体储存库的原生动物）的相互作用。我们观察到，在 25°C 下，氨基糖苷类药物处理 5 小时后，空肠弯曲菌在棘阿米巴细胞内迅速降解。相反，我们发现，在有氧条件下，37°C 时，棘阿米巴属在共培养物中促进了空肠弯曲菌的体外生长。这种促进生长的作用不需要阿米巴与细菌接触。有无接触阿米巴的情况下观察到的生长速率与在微需氧条件下生长时观察到的生长速率相似。用培养有或没有空肠弯曲菌的活或死的阿米巴制备的预处理培养基在有氧条件下不能促进空肠弯曲菌的生长。有趣的是，有无阿米巴与细菌接触的共培养物中的溶解氧水平远低于在有氧条件下与培养基或单独培养空肠弯曲菌时观察到的水平，与微需氧条件下生长 24 小时后获得的水平相当。我们的研究确定了棘阿米巴属对溶解氧的消耗是观察到的阿米巴介导的生长增强的主要原因。
