Isolation, properties and kinetics of growth of a thermophilic Bacillus

A strictly aerobic, thermophilic, spore-forming bacteria was isolated from a soil sample collected in Campos dos Goytacazes City, Rio de Janeiro, Brazil. The cells of this organism were Gram-positive, catalase positive, actively motile, 1.2 µm wide and 5.3 µm long. Growth occurred at pH values ranging from 6.5 to 9.0, and optimum growth occurred at about pH 7.0. The optimum temperature for growth was around 55ºC, and the upper temperature limit for growth was around 70ºC. Yeast extract stimulated growth on glucose and was obligately required at supraoptimal temperatures (65ºC). The results of 16S rRNA sequence comparisons indicated that the isolate was closely related to Bacillus caldoxylolyticus and Bacillus sp strain AK1, and these three organisms exhibited levels of ribossomal DNA sequence homology of 94%. Uma bactéria formadora de esporos, termofílica e aeróbica estrita foi isolada de amostras de solo coletadas na cidade de Campos dos Goytacazes, Rio de Janeiro, Brasil. As células deste organismo foram Gram-positivas, móveis e mediram 1,2 µm de largura e 5,3 µm de comprimento. O crescimento ocorreu a valores de pH variando de 6,5 a 9,0 e o crescimento ótimo ocorreu em torno de pH 7,0. A temperatura ótima de crescimento foi em torno de 55ºC e a máxima de 70ºC. O extrato de levedura estimulou o crescimento do organismo em glicose e foi obrigatoriamente requerido a supra-ótimas temperaturas (65ºC). Os resultados da comparação de seqüências de 16SrRNA indicaram que o isolado foi proximamente relacionado com o Bacillus caldoxylolyticus and Bacillus sp AK1 e estes três organismos exibiram níveis de homologia de 94% nas seqüências de DNA ribossomal