A new functional biofilm biocatalyst for the simultaneous removal of dibenzothiophene and quinoline using Rhodococcus rhodochrous and curli amyloid overproducer mutants derived from Cobetia sp. strain MM1IDA2H-1

Biocatalyst systems based on biofilms were developed to remove nitrogen and sulfur-containing heterocyclic hydrocarbons using Cobetia sp. strain MM1IDA2H-1 and Rhodococcus rhodochrous. The curli overproducers mutants CM₁ and CM₄ were derived from Cobetia sp. strain and used to build monostrain biofilms to remove quinoline; and together with R. rhodochrous to simultaneously remove quinoline and dibenzothiophene using mixed biofilms. The quinoline removal using biofilms were 96% and 97% using CM₁ or CM₄ curli overproducers respectively, whereas bacterial suspensions assays yielded 19% and 24% with the same strains. At the other hand, the simultaneous removal of quinoline and dibenzothiophene using mixed biofilms were respectively 50% and 58% using strains R. rhodochrous with CM₁ and 75% and 50% using R. rhodochrous with CM₄. Results show that biofilms were more efficient than bacterial suspension assays and that in mixed biofilms the shared surface area by two or more bacteria could affect the final yield.