Aquatic Molecular Microbial Biology

In recent years, we have been interested in the diverse epibionts associated with the globally widespread and sometimes nuisance periphytic green alga Cladophora. In addition to a diverse community of diatoms that had previously been known, we used 16S amplicon analysis to reveal a microbiota of >100 bacterial genera identifiable with current reference databases, indicating diverse biogeochemical functions. See Zulkifly et al. 2012, Am. J. Bot. 99: 1541-1552 and Zulkifly et al. 2013, J. Phycol. 49:1-17. More recent metagenomic analyses reveal that Cladophora is like a miniforest in also hosting a surprising diversity of protists, fungi, and animals. These studies suggest that Cladophora is more ecologically valuable than most people think, because this alga provides habitat for smaller organisms that play significant ecological roles. So, when you see a luxuriant Cladophora growth, don’t automatically say “yuk.”

We’ve also characterized many aspects of the microbiome of the common cyanobacterial genus Nostoc, which together with microbial associates makes distinctive frothy carbonate deposits in a Patagonian lake. These carbonates closely resemble certain Mesoproterozoic carbonates, thereby providing insight into how the ancient carbonates might have formed. See Graham et al. 2014, J. Phycol. 50: 280-91. These metagenomic studies, together with our analyses of charophycean (streptophyte) algal metagenomes focused on evolutionary questions, demonstrate that diverse algae have interesting, intimate circles of friends.