Comparison of Bacterial Diversity in Azorean and Hawai'ian Lava Cave Microbial Mats

Worldwide, lava caves host colorful microbial mats. However, little is known about the diversity of these microorganisms, or what role they may play in the subsurface ecosystem. White and yellow microbial mats were collected from four lava caves each on the Azorean island of Terceira and the Big Island of Hawai'i, to compare the bacterial diversity found in lava caves from two widely separated archipelagos in two different oceans at different latitudes. Scanning electron microscopy of mat samples showed striking similarities between Terceira and Hawai'ian microbial morphologies. 16S rRNA gene clone libraries were constructed to determine the diversity within these lava caves. Fifteen bacterial phyla were found across the samples, with more Actinobacteria clones in Hawai'ian communities and greater numbers of Acidobacteria clones in Terceira communities. Bacterial diversity in the subsurface was correlated with a set of factors. Geographical location was the major contributor to differences in community co...