• Journal of Food Hygiene and Safety
• /
• v.22 no.3
• /
• pp.151-158
• /
• 2007

Among 68 strains of lactic acid bacteria (LAB) isolated from Dongchimi, a strain K11 was selected due to its bactericidal activity against Escherichia coli O157 The strain K11 was identified as Lactobacillus plantarum, based on physiological and biochemical characteristics. In the late exponential phase, La. plantarum K11 showed maximum bacteriocin activity (12,800 BU/mL) and maintained until the early stationary phase. The bacteriocin activity was completely inactivated by all the proteolytic enzymes such as pepsin, protease, proteinase K, papain, chymotrypsin, and trypsin, but the activity was not affected by catalase, a-amylase, lysozyme, and lipase, suggesting proteinaceous nature of the bacteriocin. Additionally, this activity was not affected in the pH range from 3.0 to 9.0 and under storage conditions like 30 days at -20,4, or $25^{\circ}C$. Although the bacteriocin activity was absolutely lost after 15 min treatment at 121, it was relatively stable at $70^{\circ}C$ for 60 min or $100^{\circ}C$ for 30 min. The activity was disappeared by treatment with acetone, benzene, ethanol, or methanol, but it was not affected by treatment with chloroform or hexane. The antibacterial activity of the bacteriocin was good against some LAB including Lactobacillus spp., Enterococcus spp., and Streptococcus spp., but not against food-borne pathogens such as Bacillus spp., Listeria spp., and Staphylococcus spp. as well as yeasts and molds. Especially, some intestinal bacteria such as Enterobacter aerogenes and E. coli were significantly affected by the bacteriocin of La, plantarum K11. Furthermore, the addition of 640 BU/mL resulted in the complete clearance of E. coli O157 after 10 hr.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.33 no.10
• /
• pp.1709-1714
• /
• 2004

The changes of microflora and enzyme activities in Alaska pollack sikhae were evaluated in 3 different temperature conditions, 5$^{\circ}C$, 2$0^{\circ}C$ and alternating temperature (stored at 5$^{\circ}C$ after 10 days of fermentation at 2$0^{\circ}C$), respectively. The number of proteolytic bacteria and 2 lactic acid bacteria including Lactobacillus sp. and Pediococcus sp. increased rapidly up to 10 days and composed major portion of total viable cell (TVC) in sikhae fermented at 2$0^{\circ}C$, whereas those of TVC were occupied by Lactobacillus sp., Pediococcus sp. and yeast after 10 days of fermentation. The major species of microflora in sikhae fermented at alternating temperature were, composed of Lactobacillus, Pediococcus and Streptococcus after 10 days of fermentation. Especially, Leuconostoc sp. was kept up to 27 days at 5$^{\circ}C$ than other temperature conditions (16 days). The activities of protease and lipase in acidic region (pH 3.0) were higher at 2$0^{\circ}C$ than at 5$^{\circ}C$ due to sensitivity of temperature, although those of protease and lipase in neutral region (pH 7.0) were not found any differences in both temperatures. Changing temperature condition from 2$0^{\circ}C$ to 5$^{\circ}C$ in alternating temperature inactivated protease activity, whereas lipase activity was still maintained during fermentation.

• Journal of Dairy Science and Biotechnology
• /
• v.38 no.2
• /
• pp.89-98
• /
• 2020

The purpose of this study was to investigate the probiotic properties of lactic acid bacteria (LAB) isolated from a Korean traditional food kimchi. Gram staining was performed by Macrogen (Macrogen, Inc.) for identification of the LAB. Five strains of LAB were identified, including DKGF9 (Lactobacillus plantarum), DKGF1 (L. paracasei ), DKGF8 (L. casei ), DK207 (L. casei ), and DK211 (L. casei ). The biological activities of the isolated strains were assessed. The results showed that heat resistance of the strains was similar to or higher than the commercial strain L. acidophilus LA-5. Indirect testing of the ability of the strains to attach to the mucin layer revealed that DKGF9, DKGF1, and DKGF8 have high binding affinities for the mucous layer. All strains showed antimicrobial activity similar to or higher than the commercial strain LA-5. In proteolysis experiments, the diameters of proteolysis zones of the five strains increased in the period of 24-72 h, with DKGF1 exhibiting the largest zone diameter. Three strains were selected based on their antioxidant activities. Among the five isolated strains, L. paracasei DKGF1 showed potential probiotic activity, and thus, it may be useful for the development of health-promoting products.

• Food Science of Animal Resources
• /
• v.31 no.6
• /
• pp.952-959
• /
• 2011

A new bacteriocin-producing lactic acid bacteria (LAB) which has been isolated from kimchi was identified as Pediococcus damnosus by use of API kit and 16S rDNA sequencing, and designated as P. damnosus JNU 534. The bacteriocin produced by P. damnosus JNU 534 markedly inhibited the growth of some of LAB and Listeria monocytogenes, whereas other pathogens including Gram negative bacteria were not susceptible. The production of bacteriocin started at the beginning of exponential phase and reached maximum activity at the early stationary phase. The bacteriocin was stable on the wide pH range of 2-9 and heat treatment up to $100^{\circ}C$ for 15 min. The antimicrobial compound was inactivated by treatments of proteolytic enzymes indicating its proteinaceous in nature. The bacteriocin was purified by 30% ammonium sulfate precipitation followed by hydrophobic interaction column and $C_{18}$ column chromatography. The estimated molecular weight of the bacteriocin using tricine SDS-PAGE was approximately 3.4 kDa and the identified N-terminal amino acid sequence was $NH_2$-ILLEELNV.

• Asian-Australasian Journal of Animal Sciences
• /
• v.26 no.6
• /
• pp.820-826
• /
• 2013

The objective of this study was to determine the effect of rain tree pod meal with palm oil supplementation on feed intake, digestibility, microbial protein synthesis and microbial populations in dairy cows. Four, multiparous early-lactation Holstein-Friesian crossbred (75%) lactating dairy cows with an initial body weight (BW) of $405{\pm}40$ kg and $36{\pm}8$ DIM were randomly assigned to receive dietary treatments according to a $4{\times}4$ Latin square design. The four dietary treatments were un-supplementation (control), supplementation with rain tree pod meal (RPM) at 60 g/kg, supplementation with palm oil (PO) at 20 g/kg, and supplementation with RPM at 60 g/kg and PO at 20 g/kg (RPO), of total dry matter intake. The cows were offered concentrates, at a ratio of concentrate to milk production of 1:2, and chopped 30 g/kg of urea treated rice straw was fed ad libitum. The RPM contained condensed tannins and crude saponins at 88 and 141 g/kg of DM, respectively. It was found that supplementation with RPM and/or PO to dairy cows diets did not show negative effects on feed intake and ruminal pH and BUN at any times of sampling (p>0.05). However, RPM supplementation resulted in lower crude protein digestibility, $NH_3$-N concentration and number of proteolytic bacteria. It resulted in greater allantoin absorption and microbial crude protein (p<0.05). In addition, dairy cows showed a higher efficiency of microbial N supply (EMNS) in both RPM and RPO treatments. Moreover, NDF digestibility and cellulolytic bacteria numbers were highest in RPO supplementation (p<0.05) while, supplementation with RPM and/or PO decreased the protozoa population in dairy cows. Based on this study, supplementation with RPM and/or PO in diets could improve fiber digestibility, microbial protein synthesis in terms of quantity and efficiency and microbial populations in dairy cows.

• Microbiology and Biotechnology Letters
• /
• v.41 no.1
• /
• pp.119-127
• /
• 2013

Twenty-three strains of Leuconostoc species and 45 strains of Weissella species inhibiting the growth of Lactobacillus sakei, one of the most populous lactic acid bacteria in over-ripened kimchi, were isolated from kimchi in our previous study. Among these hetero-fermentative 68 strains, Leuconostoc mesenteroides CK0128, Weissella cibaria CK0633, and W. cibaria KK0797 exhibited a relatively high survival rate in MRS medium, which was adjusted to pH 4.3 using an acid mixture consisting of acetic and lactic acids, and produced a large amount of exopolysaccharides. The culture supernatants of 3 strains were fractionated by a molecular weight cutter and lyophilized. The fractions with a molecular weight smaller than 3,000 Da showed antagonistic activity against Staphylococcus aureus and Lb. sakei. The anti-bacterial substances were very stable to heat treatments ($121^{\circ}C$, 15 min) and active at acidic conditions below pH 5. ${\alpha}$-Amylase, lipase, and proteolytic enzymes (proteinase K and pepsin) did not affect their activities. These non-proteinaceous anti-bacterial substances inhibited the growth of several food pathogens.

• Microbiology and Biotechnology Letters
• /
• v.13 no.4
• /
• pp.409-415
• /
• 1985

This study has been carried out in order to investigate the bacterial quality of fish meat paste products and the characteristics of isolated thermodurics from the products. Twenty samples of crab-flavored fish stick (Kematsal), 23 samples of plate fish meat paste (Panomuk, Kamaboko), 5 samples of fried fish meat paste (Tigimomuk), 2 samples of roasted fish meat paste (Puduromuk, Chikuwa), 20 samples of fish sausage were collected from processing plants and supermarkets in Pusan, Korea during the period from May to October in 1984. The results obtained are as follows. Amont the samples collected from supermarkets, roasted fish meat paste and fried fish meat paste marked hish counts in coliforms and fungi while very low in the samples of crab-flavored fish stick and plate fish meat paste. Salmonella was not detected in all the samples examined and Staphylococcus aureus was detected only in fried fish meat paste, Thermoduric bacteria were detected less than 10$^2$/g in the samples of crab-flavored fish stick and plate fish meat paste, which might come from subsidiary materials such as starch and seasonings. Among the isolated bacteria, distribution of the proteolytics were more than 87％ and the lipolytics were less than 20％. Gram positive bacteria was more than 70％ in crab-flavored fish stick and plate fish meat paste, 47.3％ in fried fish meat paste. And rod in shape was almost more than 90％ in all the samples. The most heat resistant bacterium isolated from the samples was identified as a Bacillus licheniformis(named B. licheniformis CR-11). The strain showed strong proteolytic activity and also grew well at above 2$0^{\circ}C$. The growth rate and generation time of CR-11 strain were 0.31 hr$^{-1}$ , 2.24 hr at 2$0^{\circ}C$, 0.64 hr$^{-1}$ , 1.09 hr at 3$0^{\circ}C$ and 0.78 hr$^{-1}$ , 0.89 hr at 35$^{\circ}C$. Heat resistance value of the spores of CR-11 strain suspended in phosphate buffer solution was D$_{85}$ $^{\circ}C$=41.9 min, D$_{90}$ $^{\circ}C$=27.9 min, D$_{95}$ $^{\circ}C$=10.2 min, D$_{100}$ $^{\circ}C$=4.3 min (Z=13.8$^{\circ}C$)

• Journal of Dairy Science and Biotechnology
• /
• v.37 no.2
• /
• pp.115-128
• /
• 2019

Lactic acid bacteria obtained from traditional Kimchi were selected on the basis of their caseinolytic activity and lactose usability and examined for availability as a starter in probiotic activity. Thirty-two strains were selected as lactic acid producing bacteria in BCP agar, and two strains (KC23 and KF26) with more than 90% resistance for both acid and bile salts were selected. The two strains were identified as L. plantarum (KC23) and L. paracasei (KF26) by API 50 CHL system and 16S rRNA sequence analysis. L. plantarum (KC23) was finally selected based on its biochemical characteristics for lactose and raffinose usability. Free tyrosine content increased rapidly in 10% skimmed milk medium, from $24.1{\mu}g/mL$ after 8 h to $43.9{\mu}g/mL$ after 16 h. Additionally, the caseinolytic clear zone of 12 mm of L. plantarum (KC23) was greater than the 9 mm zone of commercial L. acidophilus CSLA. The bacterium exhibited mesophilic growth and yielded $8.9{\times}10^8CFU/mL$ when incubated at $37^{\circ}C$ for 12 h at pH 4.25. Moreover, L. plantarum KC23 exhibited antibacterial activity as it formed a clear zone of 8-13 mm for the 5 pathogens. Adherent activity was 2.23 fold higher than that of LGG. The acidity of 10% skimmed milk fermented for 12 h was 0.74%.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.27 no.3
• /
• pp.223-231
• /
• 1994

In order to develop the squid(Todarodes pacificus) sik-hae, the changes of TBA, fatty acids, free amino acids, and the number of microflora fermented at different fermentation temperatures and periods were determined. In addition, pretense from squid sik-hae was partially purified. The number of TBA was the highest after 5-day storage and decreased after that, and lipid oxidation was the highest at $10^{\circ}C$. The amounts of linoleic aid(18:2) and oleic acid (18:1) were about $60\%$ of fatty acid composition of squid sik-hae, and linolenic acid(18:3) and EPA(20:5) significantly decomposed with increasing fermentation periods and temperatures. Pro, His, Aeg, Leu, and Glu were composed mainly of amino acid and the composition ratios of Ser, His, and Arg decreased with increasing fermentation periods whereas, those of Glu, Ala, Val, and Tyr increased. The composition ratios of Glu, Val, and Met increased with increasing fermentation temperatures whereas, those of Ala, Cys, Thr, and Gly decreased. The number of microflora generally increased up to 15-days of storage and decreased after that. The rates of increass and decreass of the microbial number increased in proportion to fermentation temperatures. In addition, the bacteria producing proteases were identified as Bacillus spp. Proteases from $60{\sim}80\%$ ammonium sulfate concentration showed the highest activity and had about 15 binds with molecular weights between 20,000 and 40,000 Dalton by the SDS-PAGE.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.28 no.6
• /
• pp.812-813
• /
• 1995

Lactococcal cells are nutritionally fastidious and thus, generally cultured either in milk or M17 medium (Terzaghi and Sandine, 1975). In this study, Lactococcus cremoris wild-type (KH) and its less­proteolytic mutant (KHA1) cells were grown on the M17 medium or with modified M17 medium by replicated parallel experiments. The modified M17 medium had the same composition as M17 medium, except that lactose was replaced by glucose. Analyses of culture-broth samples, in which the M17 and the modified M17 media were used, were conducted by high-performance liquid chromatography (HPLC). But, working with these media created noisy problems in analyses of samples. Therefore, a new semi-synthetic medium was developed on the basis of nutritional requirements (Morishita et al., 1981). The composition of the semi-synthetic medium determined on the basis of the nutritional requirements and the composition of milk, is presented in Table 1. The composition of M17 medium is also presented and compared in the table. L. cremoris KH and KHA1 cells were grown again on the new synthetic medium containing glucose or lactose. The broth samples were then drawn and analyzed by HPLC. Clearer separations of fermented products were achieved from the new medium than those with the M17 and the modified M17 media. In comparison with the M17 or the modified M17 media, growth on the new medium was good (Kim et al, 1993). Additional fermentations were also carried out at a controlled pH of 7.0, where enhanced growth of lactococcal cells was obtained. In the fermentations, samples were also analyzed for the concentrations of sugar and lactic acid. The results showed that the new synthetic medium was as good as or better than the M 17 and the modified M 17 media. This is because casein hydrolysate in the synthetic medium provided a ready supply of amino acids and peptides for L. cremoris KH and KHA1 cells. Lactic acid bacteria (LAB) including Lactococcal cells have been known to be an effective means of preserving foods, at the same time as giving particular tastes in fields of dairy products. LAB also have always occupied an important place in the technology of sea products, and marine LAB have known to be present in traditional fermented products (Ohhira et al, 1988). To apply the new synthetic medium to marine LAB, two different LAB were isolated from pickled anchovy and pollacks caviar and were grown on the new media in which various concentrations of NaCl $(3, 5, 7 and 10\%)$ added. They were also grown on the medium solution in natural seawater $(35\%o\;salinity)$ and on the solution of natural seawater itself, too. As seen in Fig. 1, Marine LAB were grown best on the synthetic medium solution in natural seawater and the higher concentrations of NaCl were added to the medium, the longer lag-phase of growth profile appeared. Marine LAB in natural seawater were not grown well. From these results, the synthetic medium seems good to cultivate cells which are essential to get salted fish aged. In this study, it showed that the new synthetic medium provided adequate nutrition for L. cremoris KH and KHA1 cells, which have been used as cheese starters (Stadhouders et al, 1988). Using this new medium, the acid production capability of starter cultures could be also measured quantitatively. Thus, this new medium was inferior to the M17 or the modified M17 medium in culturing the cheese starters and in measuring fermentation characteristics of the starter cells. Moreover, this new medium found to be good for selected and well-identified marine LAB which are used in rapid fermentations of low-salted fish.