Specialization of Alcanivorax species in colonizing diverse plastics

Recently, there has been increased attention to hydrocarbonoclastic bacteria in the plastisphere. One particular genus, Alcanivorax, is reported in the biodegradation of several polymers in the literature. In this study, we further explored the role of Alcanivorax in the early colonization of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH), nylon 6/69, and a novel plastic B4PF01. Starting from enrichments of a one-year experiment with a maximum relative abundance of 58.8% of Alcanivorax, two parallel experiments were set up. One experiment followed growth and activity during the first 21 days of plastic incubations, and the other followed the same parameters on the different material fractions of the plastics, such as leachables and pure polymer. For all plastic types, the highest microbial growth was associated with the total plastics compared to the other material fractions. A relative abundance of 62.7% of Alcanivorax in the nylon 6/69-enriched community was observed. This, combined with data on activity, suggests that nylon 6/69 is potentially degraded by this genus. Two isolates were obtained, closely related to A. borkumensis SK2 and Alcanivorax sp. DG881. The activity and growth of the isolates as axenic cultures resemble their abundance in the community. In conclusion, this study contributes to the knowledge of the role of Alcanivorax in plastic-enriched communities.