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The Scientific World Journal
Volume 2016, Article ID 5713939, 9 pages
http://dx.doi.org/10.1155/2016/5713939
Research Article

Facilitation as Attenuating of Environmental Stress among Structured Microbial Populations

1Laboratory of Environmental Microbiology, Department of Biology, Sciences Center, Federal University of Ceará, Pici Campus, Block 909, 60455-760 Fortaleza, CE, Brazil
2Sea Sciences Institute, Federal University of Ceará, 60165-081 Fortaleza, CE, Brazil
3Graduate Program of Ecology and Natural Resources, Department of Biology, Sciences Center, Federal University of Ceará, 60455-760 Fortaleza, CE, Brazil

Received 2 October 2015; Revised 15 December 2015; Accepted 31 December 2015

Academic Editor: Béla Tóthmérész

Copyright © 2016 Suzana Cláudia Silveira Martins et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

There is currently an intense debate in microbial societies on whether evolution in complex communities is driven by competition or cooperation. Since Darwin, competition for scarce food resources has been considered the main ecological interaction shaping population dynamics and community structure both in vivo and in vitro. However, facilitation may be widespread across several animal and plant species. This could also be true in microbial strains growing under environmental stress. Pure and mixed strains of Serratia marcescens and Candida rugosa were grown in mineral culture media containing phenol. Growth rates were estimated as the angular coefficients computed from linearized growth curves. Fitness index was estimated as the quotient between growth rates computed for lineages grown in isolation and in mixed cultures. The growth rates were significantly higher in associated cultures than in pure cultures and fitness index was greater than 1 for both microbial species showing that the interaction between Serratia marcescens and Candida rugosa yielded more efficient phenol utilization by both lineages. This result corroborates the hypothesis that facilitation between microbial strains can increase their fitness and performance in environmental bioremediation.