Nancucheo Ivan, Barrie Johnson D
School of Biological Sciences, Bangor University Bangor, UK.
Front Microbiol. 2012 Sep 11;3:325. doi: 10.3389/fmicb.2012.00325. eCollection 2012.
Two acidophilic algae, identified as strains of Chlorella protothecoides var. acidicola and Euglena mutabilis, were isolated in pure culture from abandoned copper mines in Spain and Wales and grown in pH- and temperature-controlled bioreactors. The Chlorella isolate grew optimally at pH 2.5 and 30°C, with a corresponding culture doubling time of 9 h. The isolates displayed similar tolerance (10-50 mM) to four transition metals tested. Growth of the algae in liquid media was paralleled with increasing concentrations of dissolved organic carbon (DOC). Glycolic acid was identified as a significant component (12-14%) of total DOC. Protracted incubation resulted in concentrations of glycolic acid declining in both cases, and glycolic acid added to a culture of Chlorella incubated in the dark was taken up by the alga (~100% within 3 days). Two monosaccharides were identified in cell-free liquors of each algal isolate: fructose and glucose (Chlorella), and mannitol and glucose (Euglena). These were rapidly metabolized by acidophilic heterotrophic bacteria (Acidiphilium and Acidobacterium spp.) though only fructose was utilized by the more fastidious heterotroph "Acidocella aromatica." The significance of algae in promoting the growth of iron- (and sulfate-) reducing heterotrophic acidophiles that are important in remediating mine-impacted waters (MIWs) is discussed.
从西班牙和威尔士的废弃铜矿中分离出两种嗜酸藻类，分别鉴定为嗜酸原球藻变种和易变裸藻，并在纯培养物中培养，然后在pH值和温度可控的生物反应器中生长。分离出的原球藻在pH值为2.5和温度为30°C时生长最佳，相应的培养物倍增时间为9小时。这些分离物对所测试的四种过渡金属表现出相似的耐受性（10 - 50 mM）。藻类在液体培养基中的生长与溶解有机碳（DOC）浓度的增加平行。乙醇酸被确定为总DOC的重要组成部分（12 - 14%）。长时间培养导致两种情况下乙醇酸浓度均下降，添加到黑暗中培养的原球藻培养物中的乙醇酸被藻类吸收（3天内约100%）。在每种藻类分离物的无细胞滤液中鉴定出两种单糖：果糖和葡萄糖（原球藻），以及甘露醇和葡萄糖（裸藻）。这些单糖被嗜酸异养细菌（嗜酸菌属和嗜酸杆菌属）快速代谢，不过更挑剔的异养菌“芳香嗜酸单胞菌”仅利用果糖。本文讨论了藻类在促进铁（和硫酸盐）还原异养嗜酸菌生长方面的重要性，这些嗜酸菌在修复受矿山影响的水体（MIWs）中起着重要作用。
