Bacillus swezeyi sp. nov. and Bacillus haynesii sp. nov., isolated from desert soil.

Two isolates of Gram-reaction-positive, facultatively anaerobic, motile, rod-shaped, endospore-forming bacteria were identified during a survey of the diversity of strains belonging to the genus Bacillus deposited in the Agriculture Research Service Culture Collection. These strains were originally isolated from soil in Evolution Canyon III (Israel) in a survey of ecological diversification. Phylogenetic analysis of the 16S rRNA gene of strains NRRL B-41294T and NRRL B-41327T determined they were closely related to members of the Bacillus licheniformis clade.

Using null models to infer microbial co-occurrence networks.

Although microbial communities are ubiquitous in nature, relatively little is known about the structural and functional roles of their constituent organisms' underlying interactions. A common approach to study such questions begins with extracting a network of statistically significant pairwise co-occurrences from a matrix of observed operational taxonomic unit (OTU) abundances across sites. The structure of this network is assumed to encode information about ecological interactions and processes, resistance to perturbation, and the identity of keystone species.

Ecology of speciation in the genus Bacillus.

Microbial ecologists and systematists are challenged to discover the early ecological changes that drive the splitting of one bacterial population into two ecologically distinct populations. We have aimed to identify newly divergent lineages ("ecotypes") bearing the dynamic properties attributed to species, with the rationale that discovering their ecological differences would reveal the ecological dimensions of speciation. To this end, we have sampled bacteria from the Bacillus subtilis-Bacillus licheniformis clade from sites differing in solar exposure and soil texture within a Death Valley canyon.

Identifying the fundamental units of bacterial diversity: a paradigm shift to incorporate ecology into bacterial systematics.

The central questions of bacterial ecology and evolution require a method to consistently demarcate, from the vast and diverse set of bacterial cells within a natural community, the groups playing ecologically distinct roles (ecotypes). Because of a lack of theory-based guidelines, current methods in bacterial systematics fail to divide the bacterial domain of life into meaningful units of ecology and evolution. We introduce a sequence-based approach ("ecotype simulation") to model the evolutionary dynamics of bacterial populations and to identify ecotypes within a natural community, focusing here on two Bacillus clades surveyed from the "Evolution Canyons" of Israel.