1 Department of Environmental Engineering, Technical University of Denmark2 Environmental Chemistry, Department of Environmental Engineering, Technical University of Denmark3 Department of Systems Biology, Technical University of Denmark4 Center for Biological Sequence Analysis, Department of Systems Biology, Technical University of Denmark5 Urban Water Engineering, Department of Environmental Engineering, Technical University of Denmark6 Regulatory Genomics, Center for Biological Sequence Analysis, Department of Systems Biology, Technical University of Denmark7 Regulatory Genomics, Department of Biotechnology and Biomedicine, Technical University of Denmark8 University of Copenhagen9 Department of Microbiology, Technical University of Denmark
Pseudomonas putida is a versatile bacterial species adapted to soil and its fluctuations. Like many other species living in soil, P. putida often faces water limitation. Alginate, an exopolysaccharide (EPS) produced by P. putida, is known to create hydrated environments and alleviate the effect of water limitation. In addition to alginate, P. putida is capable of producing cellulose (bcs), putida exopolysaccharide a (pea), and putida exopolysaccharide b (peb). However, unlike alginate, not much is known about their roles under water limitation. Hence, in this study we examined the role of different EPS components under mild water limitation. To create environmentally realistic water limited conditions as observed in soil, we used the Pressurized Porous Surface Model. Our main hypothesis was that under water limitation and in the absence of alginate other exopolysaccharides would be more active to maintain homeostasis. To test our hypothesis, we investigated colony morphologies and whole genome transcriptomes of P. putida KT2440 wild type and its mutants deficient in synthesis of either alginate or all known EPS. Overall our results support that alginate is an important exopolysaccharide under water limitation and in the absence of alginate other tolerance mechanisms are activated.
Microbiologyopen, 2014, Vol 3, Issue 4, p. 457-469