Genes associated with antibiotic tolerance and synthesis of antimicrobial compounds in a mangrove with contrasting salinities

Highlights: • Composition and structure of actinobacteria were influenced by salinity. • Abundance of several antimicrobial biosynthesis genes were influenced by salinity. • Streptomycin and monobactam biosynthesis genes were the most abundant metabolic pathways. • Several ARG mainly associated with efflux pump mechanisms were influenced by salinity. • Our results suggest a promising scenario for bioactive compound mining in mangroves. Salinity and wastewater pollution in mangrove ecosystems can affect microorganisms and the abundance of genes involved in response to these stressors. This research aimed to identify genes associated with resistance and biosynthesis of antimicrobial compounds in mangrove soils subjected to contrasting salinities and wastewater pollution. Samples of rhizospheric soil were taken from a mangrove at the mouth of the Ranchería River in La Guajira, Colombia. A functional analysis was performed using Illumina HiSeq 2500 sequencing data obtained from total DNA extracted. Increased salt concentration influenced metabolic pathways and differential abundance of genes associated with the synthesis of antimicrobial compounds (e.g., rfbB/rffG, INO1/ISYNA1, rfbA/rffH, sat/met3, asd). Also, among 33 genes involved in intrinsic antibiotic resistance, 16 were significantly influenced by salinity (e.g., cusR/copR/silR, vgb, tolC). We concluded that salt stress tolerance and adaptive mechanisms could favor the biosynthesis of antimicrobial compounds in mangroves contaminated by sewage.