Interaction Between Hetertrophic Bacteria And Organic Carbon & Nutrients

In this thesis, Bacteria was cultivated periodically in dark place to investigate the nutrients and the bacteria growth under conditions of different organic carbon sources; in the laboratory, filtered natural seawater was inoculated into the man-made seawater system containing glucose, nitrate and phosphorus, then different parameters were determined to assess the bacteria effects on the cycling of organic carbon and nutrients. Main results are as follows:1. There are certain amount of DOM in natural seawater, and during the bacteria breeding, DOM will transform into POM. Bacteria begin to die when the concentration of DOM falls below its utilization limit, with POM degrading into DOM, which won't stop cycling until the DOC is exhausted. But DOM components are complex in natural seawater, some of which cannot be used by bacteria. Bacteria will use dissolved organic nitrogen first in seawater with both dissolved organic nitrogen and nitrate, so DON will be decomposed into nitrate by bacteria. With sufficient organic carbon, bacteria will utilize phosphate in sea water.2. Four different conditions were set by adding glutamic acid and histidine in man-made seawater respectively, and altering the accession quantities of nitrate. Then the variation tendencies of bacteria growth and different parameters were assessed to obtain some disciplinarians of bacteria utilizing amino acid:â‘ If using Glutamic acid as carbon source, the lag phase of bacteria is two days; while the histidine is used, the lag phase is five days, which implies that bacteria utilize glutamic acid more easily.â‘¡D uring exponential phase, bacteria will utilize amino acid and breed rapidly, while the concentration of DOC, DON and TOC decrease.â‘¢If amino acid is chosen as carbon source, it will import dissolved organic nitrogen...