Abstract
Selenoanalogues of the thioaminoacids, methionine and cysteine, were tested for their ability to inhibit microbial utilisation of the thioaminoacids in intertidal sediments. Concentrations of 40 μg selenoanalogue · ml
−1 sediment slurry were required to inhibit turnover of the corresponding thioaminoacid. Selenomethionine (40 μg · ml
−1) inhibited turnover of [methyl-
14C]methionine but not turnover of
l-[U-
14C]cysteine; while selenocystine (40 μg · ml
−) inhibited turnover of
l-[U-
14C]cysteine but not [methyl-
14C]methionine. The inhibition of thioamino acid turnover by the selenoanalogues was, therefore, specific. The selenoanalogues provide tools to examine the importance of the thioaminoacids during carbon flow in natural environments.