ENUMERATION OF MICROORGANISMS FROM DEEP-SEA HYDROTHERMAL CHIMNEY SAMPLES

Enumerating microorganisms from particle-laden environmental samples c an often prove difficult. Procedures involving the separation of the c ells from the particles are required, as well as an evaluation of the extraction efficiency. Here we present for the first time a method ena bling direct counts to be performed on environmental samples of deep-s ea hydrothermal Vent sulfide chimney samples. This method involves a s eparation of cells from the metallic sulfide particles by detergent an d ultrasound treatments, followed by an estimation of the extraction e fficiency by the Leslie regression method. Successful counts were obta ined from the outer portions of two active chimneys from the Mid-Atlan tic Ridge, and from the East Pacific Rise. The outer crust of these ch imneys contained up to ca. 10(10) cells g(-1) of chimney (dry weight).