Cummings B A, Caldwell D R, Gould D H, Hamar D W
Department of Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins 80523, USA.
Am J Vet Res. 1995 Oct;56(10):1384-9.
To study their role in sulfate reduction, anaerobic bacteria were cultured from rumen fluid samples of cattle fed high-carbohydrate, short-fiber diets with and without added sulfate. The steers fed the diet with added sulfate developed polioencephalomalacia. Microbiological methods included colony type profiles, molybdate sensitivity, presence of desulfoviridin, sulfate reduction rates of pure and mixed cultures, and incubation time effects on sulfate reduction. Colony-type profiles indicated decreased diversity, but no relative change in numbers of sulfate-reducing bacteria in rumen fluid from cattle fed diets with and without added sulfate. Thirteen bacteria] isolates were selected for further study on the basis of colony type, sulfate-reducing activity, and growth in lactate, sulfate, and yeast extract media. Seven of the isolates had Desulfovibrio-like characteristics (ie, they were gram-negative, motile rods that reduced sulfate, were inhibited by molybdate, and contained the pigment desulfoviridin). The remaining 6 isolates were gram-negative, nonmotile rods. Four of these released sulfide from cysteine, and 2 generated only limited amounts of sulfide from sulfate or cysteine. The 7 sulfate reducing isolates generated sulfide in rumen fluid broth medium at greater rates than those observed in fresh rumen fluid. Sulfate reduction Could be sustained in cultures for prolonged incubation times if the gas phase containing hydrogen sulfide was replaced at frequent intervals. Variations in the amount of sulfate reduced by the pure cultures were most pronounced at short incubation times. Sulfate reduction was not inhibited in mixed cultures of sulfate-reducing and nonsulfate-reducing bacteria.
为研究它们在硫酸盐还原中的作用，从喂食高碳水化合物、短纤维日粮（添加或不添加硫酸盐）的牛瘤胃液样本中培养厌氧细菌。喂食添加硫酸盐日粮的阉牛出现了脑灰质软化症。微生物学方法包括菌落类型分析、钼酸盐敏感性、脱硫绿素的存在、纯培养物和混合培养物的硫酸盐还原率以及培养时间对硫酸盐还原的影响。菌落类型分析表明多样性降低，但来自喂食添加和未添加硫酸盐日粮的牛的瘤胃液中硫酸盐还原菌数量没有相对变化。根据菌落类型、硫酸盐还原活性以及在乳酸、硫酸盐和酵母提取物培养基中的生长情况，选择了13株细菌分离株进行进一步研究。其中7株分离株具有脱硫弧菌样特征（即它们是革兰氏阴性、能运动的杆菌，能还原硫酸盐，被钼酸盐抑制，并含有色素脱硫绿素）。其余6株分离株是革兰氏阴性、不运动的杆菌。其中4株从半胱氨酸中释放出硫化物，2株仅从硫酸盐或半胱氨酸中产生有限量的硫化物。7株硫酸盐还原分离株在瘤胃液肉汤培养基中产生硫化物的速率高于在新鲜瘤胃液中观察到的速率。如果频繁更换含有硫化氢的气相，培养物中的硫酸盐还原可以在长时间培养中持续进行。纯培养物还原的硫酸盐量的变化在短培养时间内最为明显。在硫酸盐还原菌和非硫酸盐还原菌的混合培养物中，硫酸盐还原没有受到抑制。
