Abstract:
In Bolinao Bay, Pangasinan, there is a continuing accumulation
of particulate proteins in the form of fish feeds on the coastal marine
sediments because of extensive fish farming. Establishment of anoxia
and production of H2S in sediments are some of the consequences.
Hence, the influence of HS on the enzymatic degradation of
particulate proteins is the study's main concern. Initially, a
comparative study of sediments was conducted in Bolinao Bay to
establish a possible association between HS and the enzymatic
degradation of particulate proteins. Sediments near and distant from
active fish cages were collected and characterized in terms of H2S
presence, proteolytic activity. macroscopic appearance, protein content
and redox potential. Proteolytic activity of sediments was determined
in an enzyme assay using dyec-labeled scleroprotein as the enzyme
substrate. This procedure measured largely the endoenzymatic
degradation of solid protein into large dissolved molecules. The
enzyme assay was conducted in two ways, one using the sediments
directly and another using an enzyme culture fluid derived from an
enriched culture of proteolytic bacteria, which were isolated from an
oxic sediment sample. The data suggest that protein content had a
strong negative correlation with redox potential; redox potential had a
strong negative correlation with H2S presence; and H2S presence had a
moderately negative correlation with proteolytic activity. Addition of
HS to the enzyme culture fluid showed a direct inhibition on bacterial
proteases. Proteolytic activity in anoxic sediments was significantly
lower than the proteolytic activity in oxic sediments. However, the
former was not significantly different from the proteolytic activity in
anoxic sediments with H2S. These results indicate that though
hydrogen sulfide directly inhibited bacterial proteases, total proteolytic
activity was not inhibited when proteolytic enzymes were contained in
sediments. Further, removal of H2S from natural sediments did not
eliminate the inhibition of proteolytic activity.
