Diversity in UV sensitivity and recovery potential among bacterioneuston and bacterioplankton isolates

摘要

Aims: To assess the variability in UV-B (280–320 nm) sensitivity of selectedbacterial isolates from the surface microlayer and underlying water of the Riade Aveiro (Portugal) estuary and their ability to recover from previous UVinducedstress.Methods and Results: Bacterial suspensions were exposed to UV-B radiation(3Æ3 W m)2). Effects on culturability and activity were assessed from colonycounts and 3H-leucine incorporation rates, respectively. Among the tested isolates,wide variability in UV-B-induced inhibition of culturability (37Æ4–99Æ3%)and activity (36Æ0–98Æ0%) was observed. Incubation of UV-B-irradiated suspensionsunder reactivating regimes (UV-A, 3Æ65 W m)2; photosynthetic reactiveradiation, 40 W m)2; dark) also revealed diversity in the extent of recoveryfrom UV-B stress. Trends of enhanced resistance of culturability (up to 15Æ0%)and enhanced recovery in activity (up to 52Æ0%) were observed in bacterioneustonisolates.Conclusions: Bacterioneuston isolates were less sensitive and recovered morerapidly from UV-B stress than bacterioplankton isolates, showing enhancedreduction in their metabolism during the irradiation period and decreasedculturability during the recovery process compared to bacterioplankton.Significance and Impact of the Study: UV exposure can affect the diversity andactivity of microbial communities by selecting UV-resistant strains and altertheir metabolic activity towards protective strategies.