| While prior research on Bacillus methanolicus strain PB1 demonstrated growth in artificial seawater-based medium, no work has been carried out to date with Bacillus methanolicus strain MGA3. In this work, B. methanolicus strain MGA3 achieved a maximum optical density (OD) of less than 0.1 when growing in artificial seawater. The maximum OD reached 1.04 in artificial seawater medium with the addition of 2mM of each of the following reported osmoprotectants: glycine betaine, choline, proline, carnitine, glutamate, trehalose, sucrose, and methionine. In the absence of osmoprotectants, a stepwise increment in sodium chloride content in the growth medium enabled strain MGA3 to reach a maximum OD of 3.87 in minimal yeast medium at a final concentration of 25 g/l NaCl. A culture contaminant, Bacillus licheniformis, was identified during the research. With the use of a factorial design of experiment (DOE) and a mixture DOE, it was determined that glycerol and yeast extract served as carbon sources for the growth of B. licherniformis in minimal yeast medium. After adaptation, the high salt-adapted organism grew in artificial seawater with the addition of 2mM trehalose and methionine. |
