Phylogenetic diversities and community structure of members of the extremely halophilic Archaea (order Halobacteriales) in multiple saline sediment habitats

We investigated the phylogenetic diversity and community structure of members of the halophilic Archaea (order Halobacteriales) in five distinct sediment habitats that experience various levels of salinity and salinity fluctuations (sediments from Great Salt Plains and Zodletone Spring in Oklahoma, mangrove tree sediments in Puerto Rico, sediment underneath salt heaps in a salt-processing plant, and sediments from the Great Salt Lake northern arm) using Halobacteriales-specific 16S rRNA gene primers. Extremely diverse Halobacteriales communities were encountered in all habitats, with 27 (Zodletone) to 37 (mangrove) different genera identified per sample, out of the currently described 38 Halobacteriales genera. With the exception of Zodletone Spring, where the prevalent geochemical conditions are extremely inhospitable to Halobacteriales survival, habitats with fluctuating salinity levels were more diverse than permanently saline habitats. Sequences affiliated with the recently described genera Halogranum, Halolamina, Haloplanus, Halosarcina, and Halorientalis, in addition to the genera Halorubrum, Haloferax, and Halobacterium, were among the most abundant and ubiquitous genera, suggesting a wide distribution of these poorly studied genera in saline sediments. The Halobacteriales sediment communities analyzed in this study were more diverse than and completely distinct from communities from typical hypersaline water bodies. Finally, sequences unaffiliated with currently described genera represented a small fraction of the total Halobacteriales communities, ranging between 2.5% (Zodletone) to 7.0% (mangrove and Great Salt Lake). However, these novel sequences were characterized by remarkably high levels of alpha and beta diversities, suggesting the presence of an enormous, yet-untapped supply of novel Halobacteriales genera within the rare biosphere of various saline ecosystems.Peer reviewedMicrobiology and Molecular Genetic

Exploring the bioactive landscape of the gut microbiota to identify metabolites underpinning human health

The healthy human gut is colonised by a diverse microbial community (gut microbiota) that provides a variety of ecological and metabolic functions relevant to host health and well-being. Our early understanding and appreciation of the functional capacity of the microbiota was primarily informed by culture-dependent analyses. However, it is now known that the vast majority of gut microbes are resistant to cultivation and remain unrepresented by cultured isolates. Consequently, much of our current awareness of the true biological potential inherent to these communities has been provided by culture-independent (meta)genomic approaches which have revealed that the genetic potential of the gut microbiota is as much as 150 times greater than that of the human genome itself. Despite these advances it is now increasingly accepted that efforts to dissect the functionalities encoded in the human microbiome have not kept pace with DNA sequencing based technologies. For instance, the microbiome encodes a plethora of bioactive peptides and metabolites that affect host health, however, the function(s), mechanism(s) of action and the genetic and regulatory networks underpinning these bioactives remain largely cryptic. Here, we explore the NF-?B suppressive bioactive landscape of the gut microbiota-in particular, we provide an overview of our current understanding of the gut microbiota and propose the integration of new culture-dependent approaches with improved screening, metabolomic and genetic strategies offers new opportunities to identify novel bioactives, and elucidate the relationship between the gut microbiota associated metabolome and host health