Two Novel, Flavin-Dependent Halogenases from the Bacterial Consortia of Botryococcus braunii Catalyze Mono- and Dibromination

Halogen substituents often lead to a profound effect on the biological activity of organic compounds. Flavin-dependent halogenases offer possibility regioselective halogenation at non-activated carbon atoms, while employing only halide salts and molecular oxygen. However, low enzyme activity, instability, narrow substrate scope compromise use enzymatic as an economical environmentally friendly process. To overcome these drawbacks, it is tremendous interest identify novel with high scopes. Previously, Neubauer et al. developed new hidden Markov model (pHMM) based PFAM tryptophan halogenase model, identified 254 complete partial putative flavin-dependent genes in eleven metagenomic data sets. In present study, pHMM was used screen bacterial associates Botryococcus braunii consortia (PRJEB21978), leading identification several putative, genes. Two were found one gene cluster symbiont Sphingomonas sp. vitro tests revealed that both heterologously expressed enzymes are active able halogenate indole derivatives, well phenol preferring bromination over chlorination. Interestingly, SpH1 catalyses monohalogenation, SpH2 can catalyse mono- dihalogenation for some substrates.