A potentially novel aerobic, thermophilic, and cellulolytic bacterium designated as Brevibacillus sp. strain JXL was isolated from swine waste. Strain JXL can utilize a broad range of carbohydrates including: cellulose, carboxymethylcellulose (CMC), xylan, cellobiose, glucose, and xylose. In two different media supplemented with crystalline cellulose and CMC at 57 degrees C under aeration, strain JXL produced a basal level of cellulases as FPU of 0.02 IU/ml in the crude culture supernatant. When glucose or cellobiose was used besides cellulose, cellulase activities were enhanced ten times during the first 24 h, but with no significant difference between these two simple sugars. After that time, however, culture with glucose demonstrated higher cellulase activities compared with that from cellobiose. Similar trend and effect on cellulase activities were also obtained when glucose or cellobiose served as a single substrate. The optimal doses of cellobiose and glucose for cellulase induction were 0.5 and 1%. These inducing effects were further confirmed by scanning electron microscopy (SEM) images, which indicated the presence of extracellular protuberant structures. These cellulosome-resembling structures were most abundant in culture with glucose, followed by cellobiose and without sugar addition. With respect to cellulase activity assay, crude cellulases had an optimal temperature of 50 degrees C and a broad optimal pH range of 6-8. These cellulases also had high thermotolerance as evidenced by retaining more than 50% activity at 100 degrees C after 1 h. In summary, this is the first study to show that the genus Brevibacillus may have strains that can degrade cellulose.

A newly isolated Anoxybacillus sp. 527 was found to grow on crystalline cellulose as sole carbon and energy sources. Cellulases secreted by strain 527 were better induced by cellobiose, followed by glucose, lactose, sucrose, and cellulose. Cellulase secretion was enhanced by an optimized medium. Cellulase activity was increased by the addition of Ca(2+) and NH (4) (+) and achieved maximum as 7.0 FPU ml(-1) at 70 degrees C and pH 6.0. Even at 100 degrees C, the enzymes were still active, which implies their potential application in large-scale cellulose conversion process.

No abstract

No abstract

A unique thermophilic microbial community developed initially from swine waste was investigated in this study. Cellulase activities were observed when this community was inoculated to media containing either cellulose or carboxymethylcellulose at 57 degrees C. Through constructing a clone library for the 16S ribosomal DNA, it was revealed that this community was mainly composed of three genera: Thermobacillus, Brevibacillus, and Anoxybacillus. New findings regarding the thermo- and pH stability of crude cellulases secreted by Brevibacillus sp. JXL were presented. Recent study on the growth characteristics of Anoxybacillus sp. 527 was discussed.