Department of Plant and Environmental Sciences, The Institute of Life Sciences, The Hebrew University of Jerusalem, 91904 Jerusalem, Israel.
Extremophiles. 2012 Sep;16(5):787-92. doi: 10.1007/s00792-012-0476-6. Epub 2012 Aug 21.
In a metagenomic analysis of a stratified hypersaline (9 % salt) microbial mat in Guerrero Negro, Mexico, Kunin et al. (Mol Systems Biol 4:198, 2008) detected a significantly acid-shifted proteome, and concluded that adaptation by enriching proteins with acidic amino acids is more widespread than previously assumed. We here reevaluate these data and conclusions by comparing the isoelectric point profiles of the Guerrero Negro microbial mats (average isoelectric point 6.8) with those of the proteins encoded by the genomes of prokaryotes adapted to different salt concentrations ranges and belonging to different phylogenetic and physiological groups. Average isoelectric points below 6.8 were found not only in the proteomes of the moderately halophilic aerobic bacteria Halomonas elongata and Chromohalobacter salexigens, but even in common types of marine bacteria of the genera Alteromonas and Aliivibrio. We did not find clear evidence that the isoelectric point profile of the Guerrero Negro microbial mat can be considered to be the result of species-independent molecular convergence of the members of the microbial community determined by the salinity of the overlaying brine.
在对墨西哥格雷罗内格罗的分层高盐（9%盐）微生物席进行的宏基因组分析中，Kunin 等人（Mol Systems Biol 4:198, 2008）检测到明显的酸偏移蛋白质组，并得出结论，通过富集酸性氨基酸的蛋白质来适应的现象比以前认为的更为普遍。我们通过将格雷罗内格罗微生物席的等电点分布（平均等电点为 6.8）与适应不同盐浓度范围并属于不同系统发育和生理组的原核生物基因组编码的蛋白质的等电点分布进行比较，重新评估了这些数据和结论。我们发现，不仅在中度嗜盐需氧细菌 Halomonas elongata 和 Chromohalobacter salexigens 的蛋白质组中，而且在属 Alteromonas 和 Aliivibrio 等常见的海洋细菌中，平均等电点都低于 6.8。我们没有发现明确的证据表明，格雷罗内格罗微生物席的等电点分布可以被认为是由覆盖卤水盐度决定的微生物群落成员的非物种独立的分子趋同的结果。
