Microbial diversity of rizosphere in two saline chenopodiaceaes

TitleMicrobial diversity of rizosphere in two saline chenopodiaceaes
Publication TypeConference Paper
Year of Publication2010
AuthorsRuiz-Font A, Trejo-Estrada S, Lucero M.E.
Conference Name13th International Symposium on Microbial Ecology
Date Published03/2010
PublisherInternational Symposium on Microbial Ecology
Conference LocationSeattle, WA
ARIS Log Number253127
AbstractSaline environments can be found on all continents and in most countries. They consist in two primary types: those that arose from seawater and those which come from nonseawater sources. The latter contain different ion ratios where the dominant anion is typically carbonate. Plants native to saline habitats are exposed to various levels of moisture and salinity stress during their life cycle. We analyzed both soil and rhizospheric microbial communities, in plants from these environments. One of the genus Suaeda from central Mexico and other which belongs to the genus Atriplex fom the Chihuahuan desert in Nuevo Mexico, USA. In order to analyze quantitatively the microbial community rizospheric soil and soil bulk samples were processed and analyzed by traditional surface spread plating methods. The samples were plated in at least sixteen different culture media: modified R2A; modified casamino acids; BHAP; PDA; TYA and YCED medium. Each medium contained either 4% or 10% solar salt (w/v), and its pH was adjusted to either 7.0 or 9.3. Molecular analysis was also performed. Total community DNA was extracted in samples of rizospheric soil. 16s rDNA fragments amplified by PCR from soil DNA were analyzed by denaturing gradient gel electrophoresis (DGGE). Plate count methods show a high concentration of free living bacteria, 5.9x108 CFU/g, and fungi, 2.4x104 CFU/g. In bulk soil bacterial counts were is 3.0x108 CFU/g, whereas fungal counts were only is 1x103 CFU/g. Difference was found in media formulations due to high salt concentration or high pH. Medium R2A allowed the highest cultivable microbial diversity. DNA was extracted from four selected soil samples and PCR amplified with specific 16S rDNA gene primers for both bacteria and actinomycetes. The products were analyzed under different DGGE conditions. Clear differences in microbial diversity are found in rhizosphere vs bulk soil communities, as well as in cultivable vs non cultivable communities. Implications of these results in soil management and restoration are discussed.