GROWTH AND METABOLISM OF PERIPHYTIC BACTERIA: METHODOLOGY

Abstract

Procedures for determining the growth rate and studying the metabolism of periphytic bacteria are presented. The number of unicellular bacteria or the aggregate length of bacterial filaments appearing on microscope slides after immersion in the habitat for varying lengths of time was determined by direct microscopy. To distinguish on the slides between in situ growth and passive attachment of organisms from the environment, germicidal ultraviolet radiation was used. A semimicro‐assay for amount of protein on colonized glass surfaces was developed. Growth curves based on protein determinations closely resembled those based on direct microscopic counts. Growth rates were determined in the Jordan River, Indiana, and in the effluent of Trinity Springs, a large cold‐water sulfur spring. Results obtained by direct microscopic counting and by protein assay were similar. Colonized glass surfaces were also used to demonstrate uptake of radioactive substrates by the periphytic flora.