Microbial and biochemical alterations due to storage of deep-sea sediments under ambient tropical conditions

Abstract

Response of indigenous bacteria to incubation at normal pressure and tropical temperature (28 ± 2°C), were examined in four deep-sea sediments from polymetallic-nodule fields in Central Indian Basin (CIB). Sediments were stored in sterile air-tight polythene containers. Changes in microbial and biochemical parameters were monitored once in every two months for a year. Bacterial counts and ATP decreased from ~108 to ~107 g-1 and ~103 to ~101 ng g-1 dry sediment respectively, within 8-10 months before stabilization. Protein: carbohydrate ratio fluctuated considerably. The four samples responded distinctively to storage, suggesting dependence of variations on inherent sedimentary properties. Though bacteriologically and biochemically altered, the integrity of metals in sediments changed only marginally. Sediment properties evolved from a non-steady phase to a steady phase.