Monday, April 30, 2007

GFP biomonitoring by genetically modified Bacillus subtilis W1012 strain during biosurfactant production

Luiz Carlos Martins das Neves1, Marcio Junji Kobayashi1, Thaís Miranda Rodrigues1, Wolfgang Schumann2, and Thereza Christina Vessoni Penna1. (1) Department of Biochemical and Pharmaceutical Technology, School of Pharmaceutical Sciences, University of São Paulo, Av. Prof. Lineu Prestes, 580, Bl. 16, São Paulo, 05508-900, Brazil, (2) Institute of Genetics, University of Bayreuth, D-95440 Bayeruth, Bayeruth, Germany

Bacillus subtilis strains are suitable biosurfactants source and present potential application in the environmental protection by bioremediation process. The monitoring of a specific inoculum in soils is limited by the presence of indigenous microorganisms. A biomarker incorporated into the cell genome can specifically been detected without cultivation. GFP, a molecular marker, can monitor the cell growth and biosurfactant activity in a bioremediation scenario. The aim of this work was to evaluate the GFP biomonitoring capability during biosurfactant production by a new genetically modified strain of B. subtilis W1012.

Batch cultivations were performed in triplicate tests on medium containing variable levels of casein (0 – 10 g/L) and glucose (0 – 40 g/L) to follow the production of biosurfactants and GFP associated with cell growth. Results demonstrated that cell growth and biosurfactant production were associated with the cell bioluminescence. Addition of glucose up to 20g/L in the culture media improved two times the biosurfactants production by B. subtilis W1012. Nevertheless, cell growth and biosurfactants production were 20% less than observed by the non-modified strain (B. subtilis ATCC1012) when utilizing 0 to 20 g/L of glucose in culture media, probably by the energy consumed to overproduce intracellular GFP during cell growth. Moreover the work shows the potential application of GFP biomonitoring during bioremediation process in different culture conditions.