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Publications (2)5.34 Total impact

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    ABSTRACT: 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.
    Journal of Industrial Microbiology 05/2009; 36(7):961-70. · 1.80 Impact Factor
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    ABSTRACT: Gibberellins are ent-kaurene-derived diterpenoid phytohormones produced by plants, fungi, and bacteria. The distinct gibberellin biosynthetic pathways in plants and fungi are known, but not that in bacteria. Plants typically use two diterpene synthases to form ent-kaurene, while fungi use only a single bifunctional diterpene synthase. We demonstrate here that Bradyrhizobium japonicum encodes separate ent-copalyl diphosphate and ent-kaurene synthases. These are found in an operon whose enzymatic composition indicates that gibberellin biosynthesis in bacteria represents a third independently assembled pathway relative to plants and fungi. Nevertheless, sequence comparisons also suggest potential homology between diterpene synthases from bacteria, plants, and fungi.
    FEBS letters 01/2009; 583(2):475-80. · 3.54 Impact Factor