Mangrove soil as a source for novel xylanase and amylase as determined by cultivation-dependent and cultivation-independent methods

Xylanase and α-amylase enzymes participate in the degradation of organic matter, acting in hemicellulose and starch mineralization, respectively, and are in high demand for industrial use. Mangroves represent a promising source for bioprospecting enzymes due to their unique characteristics, such as fluctuations in oxic/anoxic conditions and salinity. In this context, the present work aimed to bioprospect xylanases from mangrove soil using cultivation-dependent and cultivation-independent methods. Through screening from a metagenomic library, three potentially xylanolytic clones were obtained and sequenced, and reads were assembled into contigs and annotated. The contig MgrBr135 was affiliated with the Planctomycetaceae family and was one of 30 ORFs selected for subcloning that demonstrated only amylase activity. Through the cultivation method, 38 bacterial isolates with xylanolytic activity were isolated. Isolate 11 showed an enzymatic index of 10.9 using the plate assay method. Isolate 39 achieved an enzyme activity of 0.43 U/mL using the colorimetric method with 3,5-dinitrosalicylic acid. Isolate 39 produced xylanase on culture medium with salinity ranging from 1.25 to 5%. Partial 16S rRNA gene sequencing identified isolates in the Bacillus and Paenibacillus genera. The results of this study highlight the importance of mangroves as an enzyme source and show that bacterial groups can be used for starch and hemicellulose degradation.