Diversity in UV sensitivity and recovery potential among bacterioneuston and bacterioplankton isolates.
OBJECTIVE
To assess the variability in UV-B (280-320 nm) sensitivity of selected bacterial isolates from the surface microlayer and underlying water of the Ria de Aveiro (Portugal) estuary and their ability to recover from previous UV-induced stress.


RESULTS
Bacterial suspensions were exposed to UV-B radiation (3·3 W m⁻²). Effects on culturability and activity were assessed from colony counts and (3) H-leucine incorporation rates, respectively. Among the tested isolates, wide variability in UV-B-induced inhibition of culturability (37·4-99·3%) and activity (36·0-98·0%) was observed. Incubation of UV-B-irradiated suspensions under reactivating regimes (UV-A, 3·65 W m⁻²; photosynthetic active radiation, 40 W m⁻²; dark) also revealed diversity in the extent of recovery from UV-B stress. Trends of enhanced resistance of culturability (up to 15·0%) and enhanced recovery in activity (up to 52·0%) were observed in bacterioneuston isolates.


CONCLUSIONS
Bacterioneuston isolates were less sensitive and recovered more rapidly from UV-B stress than bacterioplankton isolates, showing enhanced reduction in their metabolism during the irradiation period and decreased culturability during the recovery process compared to bacterioplankton.


CONCLUSIONS
UV exposure can affect the diversity and activity of microbial communities by selecting UV-resistant strains and alter their metabolic activity towards protective strategies.
Center for Environmental and Marine Studies (CESAM) and Department of Biology, University of Aveiro, Campus de Santiago, Aveiro, Portugal.
A L
AL
Santos
S
S
Lopes
I
I
Baptista
I
I
Henriques
N C M
NC
Gomes
A
A
Almeida
A
A
Correia
A
A
Cunha
D001419:Bacteria / Q000302:isolation & purification / Q000528:radiation effects*; D010933:Plankton / Q000302:isolation & purification / Q000528:radiation effects*; D011174:Portugal; D012623:Seawater / Q000382:microbiology; D014466:Ultraviolet Rays; D014871:Water Microbiology