@article {3093,
	title = {Biofilm Formation by Clostridium ljungdahlii Is Induced by Sodium Chloride Stress: Experimental Evaluation and Transcriptome Analysis.},
	journal = {PLoS One},
	volume = {12},
	year = {2017},
	month = {2017},
	pages = {e0170406},
	abstract = {<p>The acetogen Clostridium ljungdahlii is capable of syngas fermentation and microbial electrosynthesis. Biofilm formation could benefit both these applications, but was not yet reported for C. ljungdahlii. Biofilm formation does not occur under standard growth conditions, but attachment or aggregation could be induced by different stresses. The strongest biofilm formation was observed with the addition of sodium chloride. After 3 days of incubation, the biomass volume attached to a plastic surface was 20 times higher with than without the addition of 200 mM NaCl to the medium. The addition of NaCl also resulted in biofilm formation on glass, graphite and glassy carbon, the latter two being often used electrode materials for microbial electrosynthesis. Biofilms were composed of extracellular proteins, polysaccharides, as well as DNA, while pilus-like appendages were observed with, but not without, the addition of NaCl. A transcriptome analysis comparing planktonic (no NaCl) and biofilm (NaCl addition) cells showed that C. ljungdahlii coped with the salt stress by the upregulation of the general stress response, Na+ export and osmoprotectant accumulation. A potential role for poly-N-acetylglucosamines and D-alanine in biofilm formation was found. Flagellar motility was downregulated, while putative type IV pili biosynthesis genes were not expressed. Moreover, the gene expression analysis suggested the involvement of the transcriptional regulators LexA, Spo0A and CcpA in stress response and biofilm formation. This study showed that NaCl addition might be a valuable strategy to induce biofilm formation by C. ljungdahlii, which can improve the efficacy of syngas fermentation and microbial electrosynthesis applications.</p>},
	keywords = {Biofilms, Biomass, Carbon, Clostridium, Culture Media, Culture Techniques, Fimbriae, Bacterial, Flagella, Gene Expression Profiling, Gene Expression Regulation, Bacterial, Glass, Graphite, Osmotic Pressure, RNA, Bacterial, RNA, Ribosomal, Sodium Chloride, Spores, Bacterial, Stress, Physiological},
	issn = {1932-6203},
	doi = {10.1371/journal.pone.0170406},
	author = {Philips, Jo and Rabaey, Korneel and Lovley, Derek R and Vargas, Madeline}
}
@article {1422,
	title = {Identification and characterization of a NaCl-responsive genetic locus involved in survival during desiccation in Sinorhizobium meliloti.},
	journal = {Appl Environ Microbiol},
	volume = {79},
	year = {2013},
	month = {2013 Sep},
	pages = {5693-700},
	abstract = {<p>The Rhizobiaceae are a bacterial family of enormous agricultural importance due to the ability of its members to fix atmospheric nitrogen in an intimate relationship with plants. Their survival as naturally occurring soil bacteria in agricultural soils as well as popular seed inocula is affected directly by drought and salinity. Survival after desiccation in the presence of NaCl is enabled by underlying genetic mechanisms in the model organism Sinorhizobium meliloti 1021. Since salt stress parallels a loss in water activity, the identification of NaCl-responsive loci may identify loci involved in survival during desiccation. This approach enabled identification of the loci asnO and ngg by their reduced ability to grow on increased NaCl concentrations, likely due to their inability to produce the osmoprotectant N-acetylglutaminylglutamine (NAGGN). In addition, the mutant harboring ngg::Tn5luxAB was affected in its ability to survive desiccation and responded to osmotic stress. The desiccation sensitivity may have been due to secondary functions of Ngg (N-acetylglutaminylglutamine synthetase)-like cell wall metabolism as suggested by the presence of a d-alanine-d-alanine ligase (dAla-dAla) domain and by sensitivity of the mutant to \&beta;-lactam antibiotics. asnO::Tn5luxAB is expressed during the stationary phase under normal growth conditions. Amino acid sequence similarity to enzymes producing \&beta;-lactam inhibitors and increased resistance to \&beta;-lactam antibiotics may indicate that asnO is involved in the production of a \&beta;-lactam inhibitor.</p>
},
	keywords = {Desiccation, DNA Transposable Elements, Gene Expression Regulation, Bacterial, Gene Knockout Techniques, Genes, Bacterial, Genetic Loci, Microbial Viability, Mutagenesis, Insertional, Osmotic Pressure, Sinorhizobium meliloti, Sodium Chloride, Stress, Physiological},
	issn = {1098-5336},
	doi = {10.1128/AEM.01037-13},
	author = {Vriezen, Jan A C and de Bruijn, Frans J and N{\"u}sslein, Klaus}
}
