Immunochemical detection of dissolved proteins and their source bacteria in marine environments

Abstract

In order to expand upon the d~scovery that specific proteins survive in seawater as dissolved protein and that the ongin of these proteins is bacterial porin, we surveyed marine environments and cultured bacteria for the presence of homologues of 2 kinds of bacterial porins. Antisera against the N-terminus of the OprP porin of Pseudornonas aeruginosa and against the whole molecule of the Omp35La porin of Listonella (Vibdo) anguillarum were prepared and used as probes in Western blot analysis. In all samples collected in the subarctic and subtropical Pacific Ocean and the Antarctic Ocean, proteins reactive to the antisera were detected. The molecular ~nasses of OprP and Omp35La are 48 and 33 to 37 kDa respectively; detected proteins In seawater samples were generally also of similar molecular mass. However, dissolved proteins as well as outer membrane proteins from cultured bacteria with different molecular masses were detected using the antisera. This indicates that dissolved proteins and bacter~al outer membrane proteins distinct from OprP and Oinp35La contain similar antigenic structures to OprP and Omp35La. Fluorescent-antibody staining revealed that bacterial cells tha.t \yere stainable with antisera were present in natural bacterial assemblages throughout the entlre water column. Present observations strongly suggest that bacterial porins are a major source of dissolved proteins.