Endophytic and rhizosphere bacteria associated with the roots of the halophyte Salicornia europaea L. - community structure and metabolic potential.
The main objective of our study was to assess density and diversity of rhizosphere (R) and endophytic (E) microorganisms associated with the halophyte S. europaea. Microorganisms were isolated from two saline sites (S1: 55dSm(-1), anthropogenic origin; S2: 112dSm(-1), natural salinity) located in central Poland and compared with microbial populations in the soil (S) using culture-independent (phospholipid fatty acids analysis, PLFA) and culture-dependent techniques. The endophytic and rhizosphere bacteria were identified and screened for nifH and acdS genes, and their metabolic properties were assessed. Strains with the potential to promote plant growth were selected for further study. PLFA analysis revealed that Gram-negative bacteria were dominant at both saline test sites; the total microbial biomass depended on the site (S1<S2) and the zone of isolation (R>E>S). In contrast, culture-dependent techniques revealed that Gram-positive bacteria (Actinobacteria and Firmicutes) were dominant (S1: E-77.3%, R-86.3% and S2: E-59.1%, R-87.5%). Proteobacteria were observed in the rhizosphere at the lowest frequency (S1: 13.7% and S2: 12.5%). Greater salinity decreased the range and specificity of metabolic activity among the endophytes. These conditions also resulted in a broader spectrum of metabolic abilities in rhizobacteria; however, these metabolic processes were present at lower levels.
Department of Microbiology, Faculty of Biology and Environment Protection, N. Copernicus University, Lwowska 1, 87-100 Torun, Poland.
Sonia
S
Szymańska
Department of Microbiology, University of Silesia, Jagiellońska Street 28, 40-032 Katowice, Poland.
Tomasz
T
Płociniczak
Department of Microbiology, University of Silesia, Jagiellońska Street 28, 40-032 Katowice, Poland.
Zofia
Z
Piotrowska-Seget
Department of Microbiology, Faculty of Biology and Environment Protection, N. Copernicus University, Lwowska 1, 87-100 Torun, Poland. Electronic address: hrynk@umk.pl.
Katarzyna
K
Hrynkiewicz
D001419:Bacteria / Q000145:classification / Q000235:genetics / Q000378:metabolism; D044822:Biodiversity; D018533:Biomass; D019663:Chenopodiaceae / Q000254:growth & development / Q000382:microbiology*; D060026:Endophytes; D005227:Fatty Acids / Q000378:metabolism; D005658:Fungi; D005798:Genes, Bacterial; D010802:Phylogeny; D063245:Plant Development; D018517:Plant Roots / Q000382:microbiology*; D058441:Rhizosphere; D054712:Salinity; D055049:Salt Tolerance; D012988:Soil Microbiology
D005227:Fatty Acids
Endophytes; Phospholipid fatty acids analysis (PLFA); Rhizosphere; Salinity; acdS; nifH