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. 2015 Jun 1;10(6):e0128649.
doi: 10.1371/journal.pone.0128649. eCollection 2015.

Global Microarray Analysis of Alkaliphilic Halotolerant Bacterium Bacillus sp. N16-5 Salt Stress Adaptation

Liang Yin  1 , Yanfen Xue  2 , Yanhe Ma  2
Affiliations

Global Microarray Analysis of Alkaliphilic Halotolerant Bacterium Bacillus sp. N16-5 Salt Stress Adaptation

Liang Yin et al. PLoS One. .

Abstract

The alkaliphilic halotolerant bacterium Bacillus sp. N16-5 is often exposed to salt stress in its natural habitats. In this study, we used one-colour microarrays to investigate adaptive responses of Bacillus sp. N16-5 transcriptome to long-term growth at different salinity levels (0%, 2%, 8%, and 15% NaCl) and to a sudden salt increase from 0% to 8% NaCl. The common strategies used by bacteria to survive and grow at high salt conditions, such as K+ uptake, Na+ efflux, and the accumulation of organic compatible solutes (glycine betaine and ectoine), were observed in Bacillus sp. N16-5. The genes of SigB regulon involved in general stress responses and chaperone-encoding genes were also induced by high salt concentration. Moreover, the genes regulating swarming ability and the composition of the cytoplasmic membrane and cell wall were also differentially expressed. The genes involved in iron uptake were down-regulated, whereas the iron homeostasis regulator Fur was up-regulated, suggesting that Fur may play a role in the salt adaption of Bacillus sp. N16-5. In summary, we present a comprehensive gene expression profiling of alkaliphilic Bacillus sp. N16-5 cells exposed to high salt stress, which would help elucidate the mechanisms underlying alkaliphilic Bacillus spp. survival in and adaptation to salt stress.

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Conflict of interest statement

Competing Interests: The authors have declared that no competing interests exist

Figures

Fig 1
Fig 1. Growth curves for Bacillus sp. N16-5 grown in modified alkaline Horikoshi-II medium.
Bacillus sp. N16-5 cells were cultured in modified alkaline Horikoshi-II medium containing 0%, 2%, 8%, or 15% (w/v) NaCl.
Fig 2
Fig 2. Statistical chart of Bacillus sp. N16-5 differentially expressed genes (DEGS) in response to salt stress.
Compared to the transcriptional level at 0% NaCl, 315 genes and 331 genes were up-regulated and down-regulated, respectively, at 2% (w/v) NaCl. At 8% (w/v) NaCl, 556 genes and 578 genes were up-regulated and down-regulated, respectively, whereas 927 genes were up-regulated and 824 genes were down-regulated at 15% (w/v) NaCl.
Fig 3
Fig 3. Alterations in K+ uptake and Na+ efflux related genes.
Expression profiles are displayed on the basis of log2 ratios.
Fig 4
Fig 4. Alterations in compatible solutes related genes.
Expression profiles are displayed on the basis of log2 ratios.
Fig 5
Fig 5. Alterations in cell envelope and cell wall related genes.
(A) cell envelope related genes; (B) cell wall related genes. Expression profiles are displayed on the basis of log2 ratios.
Fig 6
Fig 6. Alterations in molecular chaperones related genes.
Expression profiles are displayed on the basis of log2 ratios.
Fig 7
Fig 7. Alterations in SigB and SigB regulon related genes.
Expression profiles are displayed on the basis of log2 ratios.
Fig 8
Fig 8. Alterations in flagellar system related genes.
Expression profiles are displayed on the basis of log2 ratios.
Fig 9
Fig 9. Alterations in iron homeostasis related genes.
Expression profiles are displayed on the basis of log2 ratios.
Fig 10
Fig 10. Growth curves of WT and Δfur at different salinities.
The WT strain and Δfur strain were cultured in modified alkaline Horikoshi-II medium containing 0% or 8% (w/v) NaCl.
See this image and copyright information in PMC

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