ระดับปริญญาเอก(Doctoral Degree)

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https://updc.up.ac.th/handle/123456789/36

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Browsing ระดับปริญญาเอก(Doctoral Degree) by Subject "Agricultural wastes"

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    การกลายพันธุ์แบคทีเรียด้วยเทคนิคพลาสมาพลังงานต่ำเพื่อผลิตอาหารหมักในโคนม
    (มหาวิทยาลัยพะเยา, 2022) นิติพล พลสา
    The aim of this work was to induce three bacterial species, including Bacillus amyloliquefaciens (cellulase-producing bacteria), Bacillus subtilis (xylanase-producing bacteria) and Enterococcus faecium (lactic acid bacteria), by using a low-energy plasma technique. The mutant bacteria were screened by hydrolysis capacity (H.C.) on carboxymethyl cellulose substrate. Then, the investigation of molecular changes, enzyme mechanisms, and fermentation processing from agricultural wastes, such as durian peel, corn cob, pineapple peel, and pineapple cork, was observed. The results showed that lactic acid bacteria, E. faecium, showed a mutant with higher lactic acid activity than control, approximately 12% under argon plasma treatment at 1.5/1.5 min on MRS broth. B. amyloliquefaciens, a cellulase-producing bacteria, was treated by low-energy plasma immersion ion implantation (PIII) to enhance their cellulase activity. According to a protein modeling analysis, replacing K370 with glutamic acid was proposed to form a hydrogen bond to Y436 a shorter distance (2.6 Å) than the control (5.4 Å), which may allow the structure to be more compact and stable, contributing to higher catalytic efficiency. Moreover, xylanase-producing bacteria, B. subtilis, were bombarded by an atmospheric pressure plasma jet (APPJ) and higher catalytic activity was screened. Sequence analysis revealed only a single amino acid substitution from threonine to serine at position 162 (T162S) to be in the glycosyl hydrolase family (GH11). To reduce feed costs, agricultural wastes were an optional choice as raw material to feed under fermentation processing, which required bacteria. The quality of fermented feed after being fermented by mutant bacteria showed that the mutant bacteria produced protein at a higher level than the control, increasing 20– 30%. The pH decreased by 10–20%, indicating the quality of fermentation associated with lactic acid content increased by 10–20%. After that, the dairy cattle were fed for a month. The amount of milk and milk composition (fat, protein, lactose, and ash) were not different from the control, although the feed cost was decreased by 40%.