ECOLOGICAL AND PHYSIOLOGICAL-STUDIES ON THERMOPHILIC BACILLI FROM SULFATARIC HOT-SPRINGS OF CENTRAL ITALY

Hot springs located in a geothermal area of central Italy were investi gated with respect to the total number of thermophilic microorganisms as well as to the presence of amylolytic and pullulolytic bacteria. A number of motile thermophilic spore-forming bacteria were isolated fro m different sites. The aerobic organisms grew optimally at 60-65 degre es C on yeast extract-trypticase and/or xylose-starch supplemented min eral medium and spores were mostly observed on agar plates after prolo nged incubation. According to the results based on phenotypic characte rization, G + C% and lipid analyses all the aerobic isolates belong to the genus Bacillus and are characterized by an unusual G + C content ranging between 33.4-38.8. A limited number of anaerobic organisms wer e also isolated and investigated for the presence of amylolytic and pu llulolytic activity. According to physiological tests these isolates w ere identified as Clostridium thermohydrosulfuricum, when grown on sta rch, they produced thermostable alpha-amylases, pullulanases and alpha -glucosidases.