SK 목장 원유의 유질 개선 시범연구

강국희,전태욱,정충일 성균관대학교 생명과학자원연구소 1996 生命資源科學硏究 Vol.3 No.1

A case study was conducted on decrease of bacteria and somatic cell count in the raw milk for the raw milk quality improvement. This study was carried on SK dairy farm in Suwon city that had 4 dairy milking cows. The experiment was tested on 2 cows each for control group and treatment group respectively. Criteria of evaluation on raw milk quality were number of total bacteria, Psychrotrophic bacteria, thermophilic bacteria, coli group and somatic cells. All the cows were applied the same feeding system for 86 days (Mar, 14∼Jane, 7) The results obtained were as follows : Milk contents were fat 3.1%∼4.19% for control group and 3.21%∼4.76% for treatment group; protein 2.65%∼4% for control and 3.04%∼4.37% for treatment; carbohydrate 4.09%∼4.86% for control and 4%∼4.94% for treatment. SNF 7.78%∼9.45% for control and 8.05%∼9.7% for treatment. There was no significant difference in milk contents between control group and treatment. The number of total bacteria was about 8.0×10 exp(5)/ml for control group and 1.0 × 10 exp(5)/ml for treatment group. Psychorotophic bacteria were distributed from 1.79 × l0P/ml to 9.55×10 exp(5) /ml for control group and 5.4×10 exp(3)/ml to 8.95×10 exp(5)/ml for treatment group. Thermophilic bacteria indicated from 6.0×10 exp(3)/ml to 8.95×10 exp(5)/ml for control group, and 5.5×10 exp(2)/ml to 1.1×10 exp(4)/ml for treatment group. The coli group indicated about from 1.6×10 exp(3)/ml to 2.3×10 exp(4)/ml for control group and 1.0×10 exp(2)/ml to 2.9×10 exp(4)/ml for treatment group. The number of somatic cells were 1,534,000(±234,012) for cow No. 2; 197,000 (±59,681) for cow No. 4; 4,240,000 (±1,094,459) for cow No. 9; 951,000 (±784,990) for cow No. 13 respectivley during the experiment period. The somatic cell count did not decrease by the sanitary handling on cows and the tools during experiment period.

GOS가 장내 Bifidobacteria의 생육촉진에 미치는 영향에 관한 연구

강국희,문지웅,강대중,이재영 成均館大學校 科學技術硏究所 1993 論文集 Vol.44 No.2

We investigated the growth effect of various sugars on the principal intestinal microorganisms which were Bifidobacteria, Lactobacilli, Streptococci, Clostridia, Escherichia, Eubacteria, and Staphylococci. Those microorganisms were cultivated on media containing various sugars. The sugars were grouped into A, B, and C. Group A consisted of sugars extracted by water, 5%, 15%, 30%, and 40%, EtOH, respectively. Group B were galactooligosaccharide(GOS), fructooligosaccharide(FOS), isomaltooligosaccharide(IMO), and xylooligosaccharide( XOS). Group C were LOS, SOS, and LSOS. Bif. adolescentis, Bif. bifidum, Bif. infantis, Bif. longum, and Str. faecalis grew well on the media containing sugars of each A, B, and C group, while C. butyricurm, S. aureus, Eu. limosum, and E. coli did not. The results indicated that oligosaccharides of A, B, and C group were consumed effectively by Bifidobacterium spp. but not utilized by other intestinal microorganisms. Oligosaccharides of each A, B, and C group promoted selectively the growth of Bif. infantis and Bif. longum in the human intestinal microflora.

Bifidobacterium angulatum으로부터 α-galactosidase의 정제 및 특성

강대중,민해기,강국희 成均館大學校 科學技術硏究所 1993 論文集 Vol.44 No.1

α-galactosidase는 (α-D-galactoside galactohydrolase: EC 3.2.1.22)는 다당류나 올리고당인 melibiose, raffinose, stachyose와 guar gum 등의 α-galactosidic 결합을 하고 있는 당을 분해하는 효소이다. 장내세균중 우익균이며 우세균주인 Bifidobacteria로부터 α-galactosidase의 효소학적 특성을 알아보기 위하여 배양여액으로부터 ammonium sulfate분획, 핵산의 제거, Sephadex G-200 gel filtration 및 DEAE-Sephadex A-50 ion exchange chromatography 등의 4단계 정제과정을 거쳐 정제한 결과 약 8배로 정제되어 단일 단백질로 분리하였다. 또한, 효소분해산물을 알아보기 위하여 TLC에 의하여 당분해 및 올리고당의 생성을 알아보았다. 정제효소의 활성 최적온도는 37℃, 최적 pH는 7.0이었다. 효소활성이 K^+, Zn^2+과 같은 금속이온과 8-Hydroxyquinoline, Sodium Bisulfite 등에 의해선 그다지 저해되지 않았으나, Hg^+, Cu^2+과 p-Chloromercuribenzoic acid에 의해선 저해되었다. 효소의 분자량이 301, 995, 합성기질인 PNPG에 대한 K_m은 0.069mM, V_max는 347.22μmol/min.mg protein이었다. To elucidate enzymatic properties of α-galactosidase (EC 3.2.1.22) from Bif.angulatum. α-galactosidase was purified to homogeneity by ammonium sulfate fractionation, protamine sulfate precipitation, sephadex G-200 gel filtration, and DEAE-sephadex A-50 ion exchange chromatography. The purified α-galactosidase was found tobbe homogeneous by SDSpolyacrylamide gel electrophoresis. The molecular weight of this enzyme, estimated by sepadex G-200 gel filtration, was about 301,995. The optimum conditions for the enzyme reaction was pH 6.5 to 7.0 at 37℃. The purified enzyme was stable at 45℃ or below and in buffer at pH 6 to 7.0. The activity was inhibited by mercury, copper ion, and p-chloromercuribenzoic acid. The kinetics of this enzyme, with p-nitrophenyl-α-D-galactoside as substrate, was determined : K_m was about 0.069mM and V_mas was 347.22 μmoles/min mg protein.

Semiconductor Gas Sensor를 이용한 유산발효중 휘발성 화합물의 측정

강국희 성균관대학교 생명과학자원연구소 1997 生命資源科學硏究 Vol.4 No.2

The measuring instrument using gas sensor was developed to determine the changes of components in lactic culture during fermentation. The gas sensor was installed in the waterbath to protect from effect of external temperature and the temperature of the waterbath was maintained as 37℃. Volatile flavor components from lactic fermentation moved to semiconductor gas sensor by carrier gas and the sensor responsed as different signal. The different signal of the sensor produced by electric pressure. The changes of the signal showed a similar tendency with those of acidity and the concentration of volatile flavor components during fermentation. The sensitivity of the sensor was highest when the velocity of the carrier gas was 30m1/min. Therefore, the gas sensor can be used to monitor and control the fermentation process.

한국성인의 腸內細菌分布에 관한 연구

姜國熙,朴勇河 成均館大學校 科學技術硏究所 1984 論文集 Vol.35 No.2

Quantitative and qualitative examination of the fecal flora of 17 clinically healthy Korean adults were carried out by using anaerobic jar culture technique. Bacteroidaceae, Bifidobacterium, Eubacterium, and Peptococcaceae were the predominant organisms approximating 10^10-10^11 in number per gram dry weight. Enterobacteriaceae, Streptococcus, Lactobacillus, and Clostridium were present in number of 10^7-10^9 per gram dry weight material, while Corynebacterium, Veillonella, and Bacillus were present in lower numbers. The human adult fecal flora was predominantly anaerobic. The aerobes are significantly less than the anaerobes and their numbers varied among specimens.

乳酸菌에 의한 돼지설사 원인균의 生育沮害

姜國熙,成文喜,李仁善,申鉉靖 成均館大學校 科學技術硏究所 1984 論文集 Vol.35 No.1

E. coli A_2 and G_7 occurring bacterial diarrhea of pigs were inoculated with 10^5/ml into thioglycollate medium without indicator-135C, and then Str. faecium and Str. faecalis var. liquefaciens were inoculated with 10^5/ml and 10^7/ml into previous inoculated samples of E. coli A_2 and G_7. Inoculated samples cultured at 37℃, were tested to determine changes in viable numbers of organisms and pH. The experimental results are summerized as follows: 1. In the mixed culture medium of 10^5/ml E. coli and 10^5/ml Streptococci, E. coli decreased after 8 hours from incubation, and finally decreased to 10^1/ml after 48 hours. 2. In the mixed culture medium of 10^5/ml E. coli and 10^7/ml Streptococci, E. coli drastically decreased, were not disappeared after 36 hours. 3. The pH value of the pure culture of E. coli was 5.30 and in the mixed culture of E. coli and Streptococci the pH value was 4.49-4.80 after 8 hours from incubation.

보리를 원료로 한 유산균음료의 제조

姜國熙,沈翰燮 成均館大學校 科學技術硏究所 1985 論文集 Vol.36 No.2

An experiment on barley yoghurt, that is cultured lactic acid bacieria in malt sugar syrup, was carried out to find out its suitability to our taste and possibly to promote domestic barley consumption. The results obtained in this experiment were as follows; 1. When we compared the sugar fermentation of three kinds of lactic acid bacteria (Lactobacillus bulg aricus, Streptococcus thermophilus, Streptococcus lactis), Str. lactis was the most suitable one. 2. The growth of lactic acid bacteria was inhibited by the low pH of malt syrup. 3. In the sensory test of samples, no significant differences were noted between market yoghurt and barley yoghurt. 4. In the sensory test, barley yoghurt made of malt sugar syrup showed the best among others.

Streptococcus faecalis var. liquefaciens 의 Plasmid 와 변이주 형질의 연관성

姜國熙,李命基,金榮勳,李春花,朴淵姬 成均館大學校 科學技術硏究所 1986 論文集 Vol.37 No.2

Lac^- and Prt^- variants were selected from Str. faecalis var. liquefaciens SKD-1007 by acrifiavin treatment. Prt^- Lac^- variant was obtained from Prt^- vaiant by mitomycin C treatment. The plasmid of variants showed same pattern with parent strain. Plasmid cured variants(SKR1, SKR2, SKR3) were obtained from parent treated by novobiocin. SKR3 variant which lost pSK6 plasmid(2.1 Mdal) was sensitive to lincomycin and erythromycin. The results implied that pSK6 plasmid of test strain was associated with antibiotic resistance (L.M, EM).

Limulus Amoebocyte Lysate법에 의한 원유와 살균유의 세균수 측정

姜國熙,王智怨,朴興洙,李圭鍾,金敬民 成均館大學校 科學技術硏究所 1993 論文集 Vol.44 No.2

LAL method for the determination of Gram-negative bacterial Lipopolysaccharides(LPS) in milk is proposed and its value for bacteriological quality control is investigated. The relationship between the LPS contents and total colony count(cfu/ml), which covers the Gram-negative bacteria, was determined in raw milk samples. The coefficient of correlation between Gram-negative bacterial counts(cfu/ml) and LPS contents was r^2 =0.969. And, the correlation coefficient between total bacterial counts(cfu/ml) and LPS contents was r^2 =0. 914. It was also investigated how much the LPS contents were in UHT milks from l0 different dairy industrial companies in Korea. It varied from 92 ng LPS/ml to 938 ng LPS /ml.

Phage耐性突然變異菌의 生育에 관한 연구

姜國熙 成均館大學校 1982 論文集 Vol.32 No.-

A comparative study has been made of growth of L. casei YIT 9018 being used as the starter of fermented milk and the phage insensitive strains obtained by treating L. casei YIT 9018 with Nitrosoguanidine. The results of cultivation parent strain YIT 9018 and 8 strains of phage insensitive stain in skimmilk at 37 C for 30 days has shown that the variables of their viable cells are nearly identical. In order to determine whether these strains are safe against frozen storage their viable cells were counted during 60 day storage at 150C. The result of the study has shown that viable cells remained nearly identical with the level of their unfrozen state. The results of examining the mean generation time of YIT 9018 and pr 38 strain is as follows: the mean generation time of YIT 9018 was 67 minutes in MRT broth and that of YIT 9018 was 86 minutes in skimmilk, while that of PR 38 recorded 63 minutes and 77 minutes in MRT broth and skimmilk respectively.