Cultivation-Dependant Assessment, Diversity, and Ecology of Haloalkaliphilic Bacteria in Arid Saline Systems of Southern Tunisia

Abstract

Haloalkaliphiles are polyextremophiles adapted to grow at high salt concentrations and alkaline pH values. In this work, we isolated 122 haloalkaliphilic bacteria upon enrichments of 23 samples from 5 distinct saline systems of southern Tunisia, growing optimally in media with 10% salt and at pH 10. The collection was classified into 44 groups based on the amplification of the 16S–23S rRNA internal transcribed spacers (ITS-PCR). Phylogenetic analysis and sequencing of the 16S rRNA genes allowed the identification of 13 genera and 20 distinct species. Three gram-positive isolates showing between 95 and 96% of 16S rRNA sequence homology with Bacillus saliphilus could represent new species or genus. Beside the difference in bacterial diversity between the studied sites, several species ecological niches correlations were demonstrated such as Oceanobacillus in salt crust, Nesterenkonia in sand, and Salinicoccus in the rhizosphere of the desert plant Salicornia. The collection was further evaluated for the production of extracellular enzymes. Activity tests showed that gram-positive bacteria were mostly active, particularly for protease, lipase, DNase, and amylase production. Our overall results demonstrate the huge phenotypic and phylogenetic diversity of haloalkaliphiles in saline systems of southern Tunisia which represent a valuable source of new lineages and metabolites.

UV‐Resistant Actinobacteria from High‐Altitude Andean Lakes: Isolation, Characterization and Antagonistic Activities

“…Moreover, representatives of the 11 genera were facultative alkaliphiles , tolerating the highest pH values. Several of the genera described in this study have been previously reported as halotolerant, for example Nesterenkonia isolated from southern Tunisia, Brazilian Mangrove sediment and hypersaline Ekho Lake in East Antarctica and Arthrobacter strains isolated from southern Tunisia . Alkaliphilic Streptomyces were likewise found in various types of soils of Georgia and in saline soils and lake sediments from China .…”

Microbial Diversity and Cyanobacterial Production in Dziani Dzaha Crater Lake, a Unique Tropical Thalassohaline Environment

“…Thirteen different taxonomic families divided into 16 genera were identified. The isolates affiliated to the genera Aliidiomarina (5), Alkalimonas (4), Bacillus (16), Cecembia (5), Halomonas (6), Nitrincola (5), Rhodobaca (2) and Vibrio (2) had already been found in similar halo-alkaline conditions [52–55]. However, the 16S rRNA gene sequence analysis may have revealed new taxa (Table 5 and S1 Text).…”

Exploring Soil Factors Determining Composition and Structure of the Bacterial Communities in Saline-Alkali Soils of Songnen Plain

“…Several recent studies on the composition of soil microbial diversity in saline soils revealed that soil salinization had negative effects not merely on soil biochemical properties, but also on the structure of microbial communities (Foti et al, 2007;Yuan et al, 2007;Hidri et al, 2013;Wang et al, 2014;Zhang et al, 2015). Regarding the soil microbial community in saline soils of Songnen Plain, only some representative new species of halophilic and halotolerant bacteria and archaea have been reported by pure culture methods (Wu et al, 2008;Wang et al, 2010;Liu et al, 2011b;He et al, 2014;Pan et al, 2016).…”