April - June 2007 - Kasetsart University

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330 3. C/N ratio Lipid accumulation in oleaginous microorganisms can be enhanced by providing excess carbon while limiting nitrogen (Ratledge, 2004). Figure 4 showed that optimum C/N ratio at 15:1 was suitable for S. limacinum BR2.1.2 in terms of growth and DHA production of 2,416.7 mg/l. Although, the cell concentration was improved (27.6 g/l) the highest biomass of 38.0 g/l was achieved in medium with C/N ratio of 20:1. CDW (g/l); DHA (% of TFA)) 60 50 40 30 20 10 0 <strong>Kasetsart</strong> J. (Nat. Sci.) 41(2) 0:1 10:1 15:1 20:1 25:1 30:1 C/N ratio CDW (g/l) DHA (% of TFA) DHA Production (mg/l) 4. Salinity Seawater was used as the source of salinity in this study. It should be noted that although S. limacinum BR2.1.2 was isolated from marine environment, it could grow and produced DHA at all levels of salinity (Figure 5). The results coincided with Yokochi et al. (1998) who reported that S. limacinum SR21 could grow in condition at zero salinity or without salt. However, a salinity equivalent to 25% of natural sea water appeared Figure 4 Effect of C:N ratio on growth and DHA production in S. limacinum BR2.1.2 cultivated at room temperature in shaker 140 rpm. CDW (g/l); DHA (% of TFA)) 45 40 35 30 25 20 15 10 5 0 0 25 50 75 100 150 200 Salinity (as % of seawater) CDW (g/l) DHA (% of TFA) DHA Production (mg/l) Figure 5 Effect of salinity (as % of seawater) on growth and DHA production in S. limacinum BR2.1.2 cultivated at room temperature in shaker 140 rpm. 3000 2500 2000 1500 1000 500 0 1200 1000 800 600 400 200 0 DHA Production (mg/l)) DHA Production (mg/l))
optimal for S. limacinum BR2.1.2 for DHA production (975.4 mg/l , 41.1% of TFA). At the highest salinity (200%), the organism showed good growth but DHA production was lowest at 277.5 mg/l This contrasts to T. aureum which fails to grow at zero salinity and also completely inhibited at 200% salinity of sea water (Iida et al., 1996). 5. Effect of temperature In this study cultures were grown in Lshaped tubes containing 10 ml medium and incubated in a temperature gradient incubator. S. limacinum BR2.1.2 grow well and produced fairly constant DHA levels at a wide range of temperature between 20-30°C. Growth of culture varied from 8.7-10.3 g/l, and DHA contents were 220-236 mg/l (Figure 6). Improvement of astaxanthin content by mutation Although, culture of S. limacinum BR2.1.2 in liquid GPY medium was creamy white color, it developed orange colonies on agar plate after several weeks of incubation. This might be explained by an accumulation of carotenoid pigments. Preliminary analysis of the pigments CDW (g/l); DHA (% of TFA)) 60 50 40 30 20 10 0 <strong>Kasetsart</strong> J. (Nat. Sci.) 41(2) 331 15 20 25 30 35 Temperature (C) CDW (g/l) DHA (% of TFA) DHA Production (mg/l) by TLC and HPLC confirmed that it was astaxanthin. Hence, it was considered to be appropriate to improve the content of this pigment in S. limacinum BR2.1.2 by mutation. If successful this organism would provide two important nutrients, i.e., DHA and astaxanthin making it suitable for animal and human consumption 1. Isolation of S. limacinum BR2.1.2 mutants From an initial S. limacinum BR2.1.2 concentration of 8.75×10 6 cells/ml, the culture was treated with NTG for 20 minutes which yielded a 0.05% cell survival rate. The treated culture was then plated on GYP medium but only one colony showed a distinctive red color. After sub-culturing for several times the deep red color persisted which showed that it was stably expressed. The mutant was then used for further investigation. The mutant grew rapidly for the first 2 days with cell concentration of 7.8 g/l. Maximum cells mass was obtained on the 6 th days at 10.8 g/l and declined gradually (Figure 7). Astaxanthin contents in cell mass increased corresponding with growth and reached highest value at 8.9 µg/ml and remained relatively constant towards the end of fermentation. This result coincided with Marvelisa Figure 6 Effect of temperature on growth and DHA production in S. limacinum BR2.1.2 cultivated in L-shaped tubes. 250 200 150 100 50 0 DHA Production (mg/l))
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April - June 2007 Volume 41 Number
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KASETSART JOURNAL NATURAL SCIENCE T
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Kasetsart J. (Nat. Sci.) 41 : 205 -
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harvesting time which started from
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y Chen and Paull (2000). Figure 1 a
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pineapple fruit allowed the accumul
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Kasetsart J. (Nat. Sci.) 41(2) 215
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Cluster analysis Cluster analysis u
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Table 3 (Continued) 1 2 3 4 5 6 7 8
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CONCLUSION AFLP markers classified
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difference of soil texture used in
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under wet soil condition planting.
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tropics. Following the expansion, w
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sealed in a plastic box with 1 cm w
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moisture content increment after so
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Frequency Frequency 30 20 10 0 20.0
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School, Kasetsart University. The a
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for combining ability of lines (Lam
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selective mass sibbing within indiv
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Although most of S 2-interfamily hy
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composite sets as used in this stud
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days. The numbers of calli producin
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the report of Ching (1982) showing
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clearly amplified bands generated b
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caused by either the recombination
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Kuhlmann, V. and B. Foroughi-Wehr.
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Xanthomonas fuscans subsp. aurantif
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was collected and washed with 70% e
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expected size was amplified with 35
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eaction technique has been used for
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Schaad, N.W., D. Opgenorth and P. G
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MATERIALS AND METHODS Model descrip
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Page 79 and 80: calculated TF value calculated TF v
Page 81 and 82: sincere gratitude and deep apprecia
Page 83 and 84: 1989). In monogastrics, the inclusi
Page 85 and 86: of all LLS samples in this study we
Page 87 and 88: Melbourne, Parkville, Victoria. Goe
Page 89 and 90: considered responsible for low prod
Page 91 and 92: Kasetsart J. (Nat. Sci.) 41(2) 291
Page 93 and 94: mineral supplementation suggested b
Page 95 and 96: Body weight chane (kg/head) 32 30 2
Page 97 and 98: CONCLUSION AND RECOMMENDATION With
Page 99 and 100: SAS. (Statistical Analysis System).
Page 101 and 102: genes covering a variety of desirab
Page 103 and 104: mg/l NAA and 0.5 mg/l zeatin) incub
Page 105 and 106: 5. Purification by various sucrose
Page 107 and 108: as the culture period increased. So
Page 109 and 110: culture, pp. 1-20. In L.C. Fowke an
Page 111 and 112: Kasetsart J. (Nat. Sci.) 41 : 311 -
Page 113 and 114: GC. Analytical methods Total carboh
Page 115 and 116: ash. The crude hot water polysaccha
Page 117 and 118: spirulan (H-SP), and a desulfated c
Page 121 and 122: cells often displayed an increased
Page 123 and 124: LITERATURE CITED Bell, T.A. and D.V
Page 125 and 126: for alternative sources of supply.
Page 127 and 128: BR2.1.2 formed the same clade with
Page 129: supplement with glutamate (Iida et
Page 133 and 134: fluorescent lamp at 1.5 kLux develo
Page 137 and 138: Wisconsin, USA). Total extracted RN
Page 139 and 140: RESULTS Cloning and sequencing of m
Page 141 and 142: Expression of rmIL-2 and purificati
Page 143 and 144: other strains of mice have differen
Page 145 and 146: dose interleukin-2 therapy promotes
Page 147 and 148: The chitosano-oligosaccharides are
Page 149 and 150: enzyme and cells were maximized by
Page 151 and 152: of crude chitosanases. Fortunately,
Page 153 and 154: Relative activity (%) 100 80 60 40
Page 155 and 156: Uchida, K. Tateishi, O. Shida and K
Page 157 and 158: MATERIALS AND METHODS 1. Materials
Page 159 and 160: without coating and coated with pec
Page 161 and 162: in Table 5-7. It was found that the
Page 165 and 166: the cultures at 10,200 × g for 15
Page 167 and 168: incubation and reached the final pH
Page 169 and 170: y lysine- and tyrosine-decarboxylas
Page 171 and 172: during the stages of ripening as su
Page 175 and 176: As the 25 companies were divided in
Page 177 and 178: All the data comes up with informat
Page 179 and 180: as piece “A” or straight as pie
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et al. (1998); Zeng (2000); and Tal
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p 1, i * Kasetsart J. (Nat. Sci.) 4
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c ≤ c2 jq2 j n q p k p * 2, j , ,
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algorithm would consider RM 5, prio
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the maximum deviation of about 10%.
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Stock Quantities Using Heuristic Op
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which dynamically and automatically
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2. Framework architecture and compo
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Risk (VaR) calculation which was im
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Throughput (job/sec) 7 6 5 4 3 2 1
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Speed up 40 35 30 25 20 15 10 5 0 F
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and discovery, resource selection a
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April - June 2007 - Kasetsart University

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