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การคัดแยกยีสต์ไขมันสูงและสภาวะที่เหมาะสมในการผลิตลิปิดโดยใช้กลีเซอรอลดิบเป็นแหล่งคาร์บอน
No full textThesis (Ph.D., Biotechnology)--Prince of Songkla University, 201
Screening of Oleaginous Yeasts and Optimization for Lipid Production Using Crude Glycerol as a Carbon Source
No full textAbstractEight hundreds and eighty nine yeast strains were isolated from soils and wastes of palm oil mill and biodiesel plant in southern region of Thailand using glucose or glycerol as carbon source and at acidic condition (pH 4.0) or neutral condition (pH 6.0) with 0.0001% chloramphenicol. By applying Sudan Black B tests, 23 strains were identified as potential lipid producer or oleaginous yeast. The lipid contents of these 23 strains were compared in crude glycerol based medium. It was found that BY4-523 accumulated highest lipid content up to 53.28% while JU4-57 grew fastest and gave comparable high lipid content 41.50%. They were identified as Kodamaea ohmeri and Trichosporonoides spathulata, respectively. Among organic nitrogen sources tested, a mixture of yeast extract and peptone (1:1) gave the best biomass (17.05g/L for T. spathulata and 11.1g/L for K. ohmeri) and the maximum lipid production (10.43g/L for T. spathulata and 4.53g/L for K. ohmeri). In the view point of economic strategy, the cheaper inorganic nitrogen sources were also tested. Among inorganic nitrogen sources tested, ammonium sulfate was selected as a suitable nitrogen source. It gave the best biomass (9.17g/L for T. spathulata and 10.45g/L for K. ohmeri) and the maximum lipid production (3.85g/L for T. spathulata and 3.17g/L for K. ohmeri). The results showed that the newly isolated yeasts could grow and accumulate high lipid content in crude glycerol based medium supplemented with only ammonium sulfate. The optimal medium composition for both strains was 0.5% ammonium sulfate and 10% crude glycerol (C/N ratio of 17). Under this condition, the maximum biomass of 10.40g/L and lipid production of 4.45g/L were achieved for T. spathulata. Similarly, K. ohmeri also reached the maximum biomass of 10.50g/L and lipid production of 3.22g/L
Cyclodextrin glycosyltransferase from a newly isolated alkalophilic <i>Bacillus</i> sp. C26
No full textA cyclodextrin glycosyltransferase (CGTase) producing bacterium was isolated from a farm soil sample and identified as Bacillus sp. C26. The highest CGTase production by Bacillus sp. C26 was achieved using 1% (w/v) sago starch and 1%(w/v) yeast extract as carbon source and nitrogen source, respectively with an initial pH of 10 and a temperature of 37oC. Other carbon sources such as soluble starch and rice starch were almost as good as sago starch but tapioca and corn were poor substrates for CGTase production. There was very little difference between the various N-sources tested i.e. peptone, tryptone and yeast extract. Under the optimal conditions, the specific growth rate and CGTase production rate of Bacillus sp.C26 were 0.193 h-1 and 5.94 U mg-1 h-1, respectively. The partially purified CGTase from Bacillus sp. C26 exhibited 2 peaks of optimum pH at 6.0 and 8.5 and had an optimum temperature of 65oC. The enzyme was stable from pH 7.0 to 9.0 and retained its high activity up to 50oC
Kinetic characteristics of β-cyclodextrin production by cyclodextrin glycosyltransferase from newly isolated Bacillus sp. C26
No full textThe kinetic characteristics of β-cyclodextrin production by a cyclodextrin glycosyltransferase (CGTase) produced by Bacillus sp. C26, a new isolate from a soil sample was investigated. Considering highest yield and initial production rate of β-cyclodextrin, among the starches examined, soluble starch, tapioca starch, sago starch, corn starch and rice starch, tapioca starch was the best substrate for this CGTase. The optimum temperature for tapioca starch gelatinization prior to its use as a substrate for β-cyclodextrin production was 65ºC. The yield and initial production rate of β-cyclodextrin increased with increasing starch concentration up to 6% and an enzyme concentration up to 48 U/g-starch. The kinetic parameters of Vmax and Km of β-cyclodextrin production from tapioca starch by CGTase were 1.59 mg/mL/h and 22.3 mg/mL, respectively. Considering high initial production rate and high yield of β-cyclodextrin, the optimum reaction temperature was at 50ºC. This study provided the necessary kinetic information that may be useful to define the most suitable condition for industrialized production ofβ-cyclodextrin with the high yield and productivity
Effect of substrate concentration and temperature on the kinetics and thermal stability of cyclodextrin glycosyltransferase for the production of β-cyclodextrin: Experimental results vs. mathematical model
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Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Kinetic characteristics of β-cyclodextrin production by cyclodextrin glycosyltransferase from newly isolated Bacillus sp. C26
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