Reducing Salinity by Flooding an Extremely Alkaline and Saline Soil Changes the Bacterial Community but Its Effect on the Archaeal Community Is Limited

Abstract

Regular flooding of the soil to reduce salinity will change soil characteristics, but also the microbial community structure. Soil of the former lake Texcoco with electrolytic conductivity (EC) 157.4 dS m-1 and pH 10.3 was flooded monthly in the laboratory under controlled conditions for 10 months while soil characteristics were determined and the archaeal and bacterial community structure monitored by means of 454 pyrosequencing of the 16S rRNA gene. The EC of the soil dropped from 157.8 to 1.7 dS m-1 and the clay content decreased from 430 to 270 g kg-1 after ten floodings, but the pH (10.3) did not change significantly over time. Flooding the soil had a limited effect on the archaeal community structure and only the relative abundance of Haloferax-like 16S rRNA phylotypes changed significantly. Differences in archaeal population structure were more defined by the initial physicochemical properties of the soil sample than by a reduction in salinity. Flooding, however, had a stronger effect on bacterial community structure than on the archaeal community structure. A wide range of bacterial taxa was affected significantly by changes in the soil characteristics, i.e., four phyla, nine classes, 17 orders, and 28 families. The most marked change occurred after only one flooding characterized by a sharp decrease in the relative abundance of bacterial groups belonging to the Gammaproteobacteria, e.g., Halomonadaceae (Oceanospirillales), Pseudomonadaceae, and Xanthomonadaceae and an increase in that of the [Rhodothermales] (Bacteroidetes), Nitriliruptorales (Actinobacteria), and unassigned Bacteria. It was found that flooding the soil sharply reduced the EC, but also the soil clay content. Flooding the soil had a limited effect on the archaeal community structure, but altered the bacterial community structure significantly.

Desiccation- and Saline-Tolerant Bacteria and Archaea in Kalahari Pan Sediments

“…The relative abundance of Bacteroidetes , Chloroflexi , and Proteobacteria is comparably low in Witpan. The sequences related to Bacteroidetes Incertae Sedis – known as Rhodothermales and Cytophagia – can be classified within Bacteroidetes and have recently been identified in alkaline and saline soils ( de Leon-Lorenzana et al, 2017 ) as well as in microbial mats ( Fernandez et al, 2016 ). In pan sediments, the members of thermophilic Chloroflexi have been assigned to Dehalococcoidetes , which uses organohalide respiration for energy conservation ( Kaster et al, 2014 ).…”

Prokaryotic Community Distribution along an Ecological Gradient of Salinity in Surface and Subsurface Saline Soils

“…Within Proteobacteria , most saline samples (16/23) were dominant by Gammaproteobacteria , and Arit S. de León-Lorenzana et al . 44 has observed a sharp relative abundance decrease of Gammaproteobacteria by flooding a saline soil, suggesting Gammaproteobacteria was more adaptive to saline environments than other proteobacterial classes. Moreover, it confirmed the widespread distribution of Halobacteria of Archaea , Proteobacteria of Bacteria in soils.…”

Environmental Nutrients Alter Bacterial and Fungal Gut Microbiomes in the Common Meadow Katydid, Orchelimum vulgare

“…While multiple Corynebacterium species are notable human pathogens (Bernard, 2012), other research has identified isolates of this genus that are highly associated with sugarcane rhizosphere with increased soil salinity (Pirhadi, 2018). Phyllobacteriaceae and Streptococcaceae were also indicator groups for added Na and are bacterial families previously identified to be associated with high saline soil microbiomes (de León-Lorenzana et al, 2017;Genderjahn et al, 2018). Listeraceae and Propionibacteriaceae, additional indicator groups for added Na, are also families with species that are capable of growth in relatively high concentrations of Na (Labadie et al, 2003;Liu et al, 2005).…”