Martins Juliana L, Silveira Thaís S, Silva Karen T, Lins Ulysses
Department of General Microbiology, Professor Paulo de Góes Institute of Microbiology, Federal University of Rio de Janeiro, Rio de Janeiro, RJ, Brazil.
Int Microbiol. 2009 Sep;12(3):193-201.
Candidatus Magnetoglobus multicellularis is an unusual magnetotactic multicellular microorganism composed of a highly organized assemblage of gram-negative bacterial cells. In this work, the salinity dependence of Ca. M. multicellularis and its abundance in the hypersaline Araruama Lagoon, Brazil were studied. Viability experiments showed that Ca. M. multicellularis died in salinities upper than 55 per thousand and lower than 40 per thousand. Low salinities were also observed to modify the cellular assemblage. In microcosms prepared with different salinities, the microorganism grew better at intermediate salinities whereas in high or low salinities, the size of the population did not increase over time. The concentrations of Ca. M. multicellularis in the lagoon were related to salinity; sites with lower and higher salinities than the lagoon average contained less Ca. M. multicellularis. These results demonstrate the influence of salinity on the survival and distribution of Ca. M. multicellularis in the environment. In sediments, the abundance of Ca. M. multicellularis ranged from 0 to 103 microorganisms/ml, which represented 0.001% of the counts of total bacteria. The ability of Ca. M. multicellularis to accumulate iron and sulfur in high numbers of magnetosomes (up to 905 per microorganism) suggests that its impact on the sequestration of these elements (0.1% for biogenic bacterial iron) is not proportional to its abundance in the lagoon.
“多细胞球形磁球菌候选种”是一种不同寻常的趋磁多细胞微生物，由革兰氏阴性细菌细胞高度有序聚集而成。在本研究中，对“多细胞球形磁球菌候选种”的盐度依赖性及其在巴西高盐度阿拉鲁阿马泻湖中的丰度进行了研究。活力实验表明，“多细胞球形磁球菌候选种”在盐度高于千分之五十五和低于千分之四十时死亡。还观察到低盐度会改变细胞聚集情况。在不同盐度制备的微观环境中，该微生物在中等盐度下生长得更好，而在高盐度或低盐度下，种群数量不会随时间增加。泻湖中“多细胞球形磁球菌候选种”的浓度与盐度有关；盐度低于或高于泻湖平均水平的区域所含的“多细胞球形磁球菌候选种”较少。这些结果证明了盐度对“多细胞球形磁球菌候选种”在环境中的生存和分布的影响。在沉积物中，“多细胞球形磁球菌候选种”的丰度范围为每毫升0至103个微生物，占细菌总数的0.001%。“多细胞球形磁球菌候选种”能够在大量磁小体（每个微生物多达905个）中积累铁和硫，这表明其对这些元素的螯合作用（生物源细菌铁占0.1%）与其在泻湖中的丰度不成比例。
