Mixtures of Pseudomonas putida CECT 5279 cells of different ages: optimization as biodesulfurization catalyst.

Abstract

Sulfur contentinfossilfuelsisknowntobethemostimportantanthropogeniccauseofsulfuroxide emissions totheatmosphere.Inordertoavoidhealth,environmentalandtechnicalproblemscaused by thiscompound,legislationimposesrestrictivelimitationstofuelsulfurcontent.Biodesulfurization (BDS) canbecomeacomplementarytechnologytohydrodesulfurization(HDS)tofacethissituation. Pseudomonas putida CECT 5279isageneticallymodifiedmicroorganismwhichcanactasadesulfurizing biocatalyst. Thismicroorganismhastheabilityofperformingthemetabolic4Spathwayfrom Rhodococcus erythropolis IGTS8, inordertodesulfurizeDBT,asamodelcompound.Maximum in vivo activities of monooxygenase enzymes(DszAandDszC)areshownwhenlateexponentialgrowthphaseisreached (23 h),whiledesulfinaseenzymeDszBpresentsamaximumactivityduringtheearlyexponentialgrowth phase (5h),aspreviouslyreported [1]. Also,ithasbeenprovedthatthecombinedutilizationofthesetwo cell agesyieldsexcellentresultswhenusedasbiocatalystfordesulfurization [2]. Theaimofthisworkis to optimizetheratioandtotalbiomassconcentrationofboth5hand23hgrowthtimecellsinacomplex biocatalyst fordesulfurizationbyperformingrestingcellsbiodesulfurizationassaysusingdibenzothio- phene (DBT)assulfurmodelcompound.Thebestcombinationofcellswasdeterminedaimingforthe highest desulfurizationintheshortesttimeofoperationwhileinvestingtheminimumconcentrationof biomass. Aparticularcellmixture,containing66.7%of23hgrowthtimecells,wasfoundtoworkasthe most effectivedesulfurizationbiocatalyst.