Study of Bacterial Community Composition and Correlation of Environmental Variables in Rambla Salada, a Hypersaline Environment in South-Eastern Spain
Metadatos
Afficher la notice complèteAuteur
Oueriaghli, Nahid; Castro, David; Llamas Company, Inmaculada; Béjar Luque, María Victoria; Martínez-Checa Barrero, Fernando JoséEditorial
Frontiers Media
Materia
Biodiversity Bacteria Hypersaline habitat Rambla Salada DGGE Dilution-to-extinction methods
Date
2018Referencia bibliográfica
Oueriaghli N, Castro DJ, Llamas I, Béjar V and Martínez-Checa F (2018) Study of Bacterial Community Composition and Correlation of Environmental Variables in Rambla Salada, a Hypersaline Environment in South-Eastern Spain. Front. Microbiol. 9:1377. [http://hdl.handle.net/10481/56741]
Patrocinador
This research was supported by grants from the Dirección General de Investigación Científica y Técnica (CGL2005-05947; CGL2008-02399; CGL2011-25748), Ministerio de Economía y Competitividad and from the Plan Andaluz de Invesigacion (P07-CVI-03150; CVI06226), Spain.Résumé
We studied the bacterial community in Rambla Salada in three different sampling
sites and in three different seasons and the effect of salinity, oxygen, and pH.
All sites samples had high diversity and richness (Rr > 30). The diversity indexes
and the analysis of dendrograms obtained by DGGE fingerprint after applying
Pearson’s and Dice’s coefficient showed a strong influence of sampling season. The
Pareto-Lorenz (PL) curves and Fo analysis indicated that the microbial communities
were balanced and despite the changing environmental conditions, they can preserve
their functionality. The main phyla detected by DGGE were Bacteroidetes (39.73%),
Proteobacteria (28.43%), Firmicutes (8.23%), and Cyanobacteria (5.14%). The majority
of the sequences corresponding to uncultured bacteria belonged to Bacteroidetes
phylum. Within Proteobacteria, the main genera detected were Halothiobacillus and
Roseovarius. The environmental factors which influenced the community in a higher
degree were the salinity and oxygen. The bacteria belonging to Bacteroidetes and
Proteobacteria were positively influenced by salinity. Nevertheless, bacteria related to Alpha- and Betaproteobacteria classes and phylum Firmicutes showed a positive
correlation with oxygen and pH but negative with salinity. The phylumCyanobacteria were
less influenced by the environmental variables. The bacterial community composition
of Rambla Salada was also studied by dilution-to-extinction technique. Using this
method, 354 microorganisms were isolated. The 16S sequences of 61 isolates
showed that the diversity was very different to those obtained by DGGE and with
those obtained previously by using classic culture techniques. The taxa identified by
dilution-to-extinction were Proteobacteria (81.92%), Firmicutes (11.30%), Actinobacteria
(4.52%), and Bacteroidetes (2.26%) phyla with Gammaproteobacteria as predominant
class (65.7%). The main genera were: Marinobacter (38.85%), Halomonas (20.2%),
and Bacillus (11.2%). Nine of the 61 identified bacteria showed less than 97%
sequence identity with validly described species and may well represent new taxa.
The number of bacteria in different samples, locations, and seasons were calculated
by CARD-FISH, ranging from 54.3 to 78.9% of the total prokaryotic population. Inconclusion, the dilution-to-extinction technique could be a complementary method to
classical culture based method, but neither gets to cultivate the major taxa detected by
DGGE. The bacterial community was influenced significantly by the physico-chemical
parameters (specially the salinity and oxygen), the location and the season of sampling.