In situ cultivation technique allows recovery of native bacterial types competitive in their extreme cold environment of northern Greenland
1Hiroshima Univ. ISSD., 2Northeastern Univ. Biol.
The vast majority of microorganisms do not grow under standard laboratory conditions. On the other hand, it has been shown that in situ cultivation techniques improved the result of cultivation, in terms of novelty of isolates as well as overall recovery rate. To explain this phenomenon, we tried to find out whether there was a clear difference of physiological properties between the two groups of isolates from in situ and conventional methods. Several isolates were obtained from Greenland soil using diffusion chamber (in situ cultivation) and Agar-Petri plate (conventional). Then, the growth rates under different temperatures were comparatively analyzed. As a result, while the overall optimal growth temperatures were similar, of the temperatures offered, they behaved differently at the extremes. Under cold conditions (similar to their native habitat), the “in situ -isolates” did not show a decrease in growth rate as the temperature fell; whereas, “Petri-isolates” showed a significant decrease. The growth rates of the “in situ -isolates” exceeded that of the “Petri-isolates” only at 0 _C. These results suggested that in situ cultivation allows for the recovery of bacterial types that are out-competed by ubiquitous types in the lab. However, “in situ -isolates” only out-compete them in the native environment.
keywords:In situ cultivation ,growth rate,Psychrophilic bacteria,Greenland