ARS | Publication request: Diversity of rhizospheric halotolerant bacteria associated with chenopod plants Atriplex and Suaeda.

Submitted to: Biomicroworld Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: July 21, 2011
Publication Date: N/A

Technical Abstract: Plants growing in saline soils are exposed to various levels of moisture and salinity stress during their life cycle. Plant associated microbes may help mediate such stress. We analyzed rhizospheric, soil and leaf litter microbial communities associated with two saline-adapted chenopod plants, Suaeda mexicana, from central Mexico and Atriplex canescens, from the Chihuahuan Desert region of the United States. In order to characterize the cultivable microbial community, soil and leaf litter samples were processed and analyzed by traditional surface spread plating methods. The samples were plated on sixteen different culture media: modified R2A; Casamino acids; BHAP; PDA; TYA and YCED. Each medium contained either 4% or 10% NaCl (w/v), and was adjusted to either neutral or basic pH. Cells of 43 strains, selected as representatives of the cultivated isolates, were lased by freeze-boiling and directly applied to PCR mixtures. Amplification of 16S rDNA fragments was carried out using the primer pairs F984GC-R1378 for bacteria and ITS1F-ITS4 for the sole fungal isolate. Sequences obtained from PCR products obtained from Atriplex isolates were homologous to sequences of the bacterial genera Penibacillus, Streptomyces, Promicromonospora, Rhodococcus, Bacillus and Pseudomonas, and the fungal genus Aspergillum. Sequences homologous to the genera Artrhobacter, Streptomyces, Nocardia, Cellulosimicrobium, Pseudomonas and Bacillus were amplified from Suaeda isolates. Total DNA was extracted from samples of soil and leaf litter in different seasons (winter and spring). Using a Universal Bacterial 16S Primer, Tag-Encoded FLX Amplicon Pyrosequencing (TEFAP) was used to assess microbial diversity. Each of the isolates was used for the inoculation of anemically grown Amaranthus spp. Under different concentrations of NaCl (0-1%) and plant growth promotion was evaluated.