INFLUENCE OF PH AND TEMPERATURE ON ENUMERATION OF CELLULOSE-DEGRADINGAND HEMICELLULOSE-DEGRADING THERMOPHILIC ANAEROBES IN NEUTRAL AND ALKALINE ICELANDIC HOT-SPRINGS

Cellulose- and hemicellulose-degrading thermophilic anaerobes were enu merated in biomat samples of various temperatures from two different h ot springs in the Hverageroi area of Iceland: one spring had a pH near 7, the second had a pH near 9. The most-probable-number technique was used for enumeration of bacteria in the samples, with media at many d ifferent temperatures (37 to 90-degrees-C) and two pH values (7 and 9) . There were generally more xylan-degrading then cellulose-utilizing o rganisms in both environments. There was no growth at 80-degrees-C in the neutral spring or at 37-degrees-C in the alkaline spring. However, there were large numbers of both types of organisms in the alkaline s pring at 80-degrees-C and in the neutral spring at 37-degrees-C. No cu ltures grew from the most-probable-number tubes inoculated with the Hv erageroi samples and incubated at 90-degrees-C or with media at pH 9. However, xylan-degrading cultures at 70-degrees-C were enriched at pH 9 with samples from some other Icelandic hot springs.