Bacterial cells, enzymatic lysis

The isolation of bacterial DNA described in this experiment, patterned after the work of Marmur (1961), accomplishes these objectives. Bacterial cells are disrupted by initial treatment with the enzyme, egg-white lysozyme, which hydrolyzes the peptidoglycan that makes up the structural skeleton of the bacterial cell wall. The resultant cell walls are unable to withstand osmotic shock. Thus, the bacteria lyse in the hypotonic environment. The detergent, sodium dodecyl sulfate, (SDS, sodium do-decyl sulfate) then completes lysis by disrupting residual bacterial membranes. SDS also reduces harmful enzymatic activities (nucleases) by its ability to denature proteins. The chelating agents, citrate and EDTA (ethylenediamine tetraacetic acid), also inhibit nucleases by removing divalent cations required for nuclease activity. 

When phytoplankton cells die for some reason (e.g. lysis) the soluble components will leave the cell to the external medium. The insoluble cellular material left has a relatively high chemical stability, but degradation may be greatly enhanced by enzymatically catalyzed reactions. Where are enzymes located It seems less probable to find active enzymes suspended in sea water - most of them are extracellular enzymes located on the bacterial cell surface [71 ]. Active bacteria are partly free hving in the water and partly attached to phytoplankton cells [71-73]. 

A new system for the enzymatic production of L-aspartate was proposed and started in the 1990s. In this system, resting intact cells of coryneform bacteria were used without immobilization and with an ultrafiltration membrane. This bacterial strain possesses high maleate isomerase and aspartase activities thorough transformation of their genes. The plasmids introduced were stabilized and the cells were reused many times without any loss of activity and lysis [17]. 

---