Dextran is a generic term for a bacterial exopolysaccharide synthesized from sucrose and composed of chains of D-glucose units connected by α-1,6-linkages by using dextransucrases. Dextran could be used as vicosifying, stabilizing, emulsifying, gelling, bulking, dietary fiber, prebiotics, and water holding agents. We isolated new strain capable of producing dextran from Korean traditional kimchi and identified as Leuconostoc sp. strain JYY4. Batch fermentation was conducted in bioreactor with a working volume of 3 L. The media was MMY and 15% (w/v) sucrose. Mineral medium consisted of 3.0 g KH2PO4, 0.01 g FeSO4, H2O, 0.01 g MnSO4, 4H2O, 0.2 g MgSO4 7H2O, 0.01 g NaCl, 0.05 g CaCl2 per 1 liter deionized water. The pH of media was initially adjusted to 6.0. The inoculation rate was 1.0% (v/v) of the working volume. Temperature was maintained at 28oC. The agitation rate was 100 rpm. The production pattern of dextran was associated with the cell growth. After 24 hr dextran reached its highest concentration of 59.4 g/L. The sucrose was consumed completely after 40 hr. Growth reached stationery phase when sucrose became limiting, regardless of the presence of fructose or mannitol. When the specific growth rate was 0.54 hr-1, utilization averaged 5.8 g/L-hr. The yield and productivity of dextran were 80% and 2.0 g/L-hr, respectively. Dextrans produced by were separated to two different size by an alcohol fraction method. The size of high molecular weight dextran (45% alcohol, v/v), less soluble dextran, was between MW 500,000 and 2,000,000. Soluble dextran (55% alcohol, v/v) was between 70,000 and 150,000. The molecular weight average of total dextran (70% alcohol, v/v) was between 150,000 to 500,000. The enzymatic hydrolyzates of total dextran of ATCC 13146 showed branched dextrans by Penicillium dextranase contained of glucose, isomaltose, isomaltotriose, and isomaltooligosaccharides greater than DP4 (degree of polymerization) that had branch points. Compounds greater than DP4 were branched isomaltooligosaacharides. Hydrolysates by the Lipomyces dextranase produced the same composition of oligosaccharides as those by Penicillin dextranase.

The prediction of male fertility is of paramount importance for breeding animal herds when artificial insemination is applied. While the male fertility assays provide valuable quantitative data, they yield limited information concerning the functional competence of the spermatozoa. The objective of this study was to standardize a method for predicting in vivo fertility in bulls using the capacitation status that was assessed by chlortetracycline (CTC) staining. To optimize the capacitation process, sperm were treated with various concentrations of heparin (0, 10, 20, 50, and 100 μg/mL) and incubated for 10, 20, and 30 min each at 39℃ in 5% CO2. We found that maximum capacitation condition obtained from 10 μg /mL heparin treated sperm cells for 20 min (p<0.05). Optimized methods were used to determine the fertility of 17 batches of frozen bull semen representing a wide range of field fertility levels as indicated by non-return rates (NRR) (35.29% 93.18%). There was no significant correlation between NRR and the percentage of capacitated spermatozoa (B type) and non-capacitated spermatozoa (F type). However, acrosome reacted spermatozoa (AR type) was significantly correlated with NRR (p<0.01). To determine the normal range for the AR type, lower limits of the AR (%) were established as 23% for low fertility (NRR < 75%) using receiver operating characteristic curve. The overall accuracy of the assay was 88.24% for low fertility, sensitivity and specificity were 81.82 and 100%, respectively. These results indicate that capacitation status as measure by CTC staining is a useful predictor of male fertility. Therefore, low and high fertility bulls can be identified primarily by the functional capacitation status.