• Preventive Nutrition and Food Science
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• v.5 no.3
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• pp.153-159
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• 2000

A 4.4 kb DNA fragment encompassing lacA (galactoside acetyltransferase) and lacZ($\beta$-galactosidase) genes from Lactococus lactis ssp. lactis ATCC 7962 (L. lactis 7962) was introduced ito a Lac strain, Lactococcus lactis ssp. lactis MG1363 (L. lactis MG1363) by using a lactococcal expression vector, pMG36e and expression level of lacZ was examined. Growth rates and $\beta$-galactosidase ($\beta$-gal) activities of MG1363 cells carrying recombinant plasmid, pMLZ3, on M17 broth containing different carbon sources (1%, w/v) were examined. Contrary to the expectations, MG1363 [pMLZ3] grown on lactose showed the lowest enzyme activity (17 units) and cells grown on galactose had the highest $\beta$-gal activity (41 units). Cells grown on glucose had intermediate activity (33 units). These activities are about one tenth of the values observed in L. lactis 7962 where lacZ is present as a single-copy gene in the chromosome. When the cellular concentrations of lacZ transcript were examined using slot blot hybridization, it was found that MG1363[pMLZ3] produced sufficient amounts of transcript. These results indicate that either proteolytic degradation of $\beta$-gal or other regulatory mechanism prevent the translation or accumulation of $\beta$-gal in L. lactis MG1363 cells. In regard to regulation, the presence of the ccpA gene in L. lactis MG1363 was confirmed by Southern blot.

• Korean Journal of Microbiology
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• v.27 no.3
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• pp.181-187
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• 1989

Plasmid DNA was isolated from Lactobacillus casei SW-M1($Lac^{+}$strain). The curing frequencies of pPLac plasmid from L. casei SW-M1 showed 43% for acriflavin treatment and 53% for ethidium bromide treatment after 3 times transfer. On the charaterization of pPLac plasmid, it was found that the plasmid contained gene encoding phospho-$\beta$-galactosidase for lactose utilization. Lactose-PTS(phosphotransferase system)was involved in membrane transport system in $Lac^{+}$ strain. Induction of phospho-$\beta$-galactosidase was specially effective by galactose, lower effect with lactose and glucose but not by IPTG(isopropyl-$\beta$-D-thiogalactoside). This result showed that induction of phospho-$\beta$-galactosidase by IPTG did not appeared. The catabolite repression of phospho-$\beta$-galactosidase synthesis by glucose was not found in L. casei.

• Microbiology and Biotechnology Letters
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• v.19 no.2
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• pp.147-152
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• 1991

In order to study effect of the phage ${\phi}$ FSV on the growth of lactic acid bacteria, Lactobacillus casei YIT 9018(wild type strain with prophage) or L. casei HYM 1213 (prophage cured strain) was infected with various concentrations of phage ${\phi}$ FSV (called Lac S21) or wild type virulent phage (called Lac J-1). When L. casei YIT 9018 was infected with Lac S21 under the concentration of $6.0{\times}10^6$ pfu/ml, the growth and lactic acid production of the strain were normal and the number of phages decreased. But L. casei HYM 1213 was susceptible to Lac S21. Regardless of the concentration of the phage infection, the number of phages increased rapidly into $10^9$ to $10^{10}$ pfu/ml at 2 day cultures and was maintained $10^7$ to $10^9$pfu/ml phage until 6 day cultures. The lactic acid production of L. casei HYM 1213 infected with Lac S21 was abnormal. Therefore, phage ${\phi}$ FSV had an evil effect on growth of L. casei HYM 1213, but not L. casei YIT 9018. On the other hand Lac J-1 caused abnormal fermentation to either L. casei YIT 9018 or L. casei HYM 1213.

• Korean Journal of Food Science and Technology
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• v.16 no.4
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• pp.443-450
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• 1984

Chemical and microbial changes during Kimchi (a group of Korean seasoned pickles) fermentation were carried out at various temperatures and salt concentrations. The time reaching optimum ripening of Kimchi varied depending upon fermentation temperature and salt concentration. At high temperature and low salt content Kimchi fermentation was faster than at low temperature and high salt content. The ratio of volatile to non-volatile acids reached its maximum at the optimum ripening time of Kimchi and decreased thereafter. Leu. mesenteroids, Lac. brevis, Lac. plantarum, Ped. cerevisiae, Str. faecalis and low acid producing Lactobacilli were isolated from Kimchi samples. However, the main microorganism responsible for Kimchi fermentation was Leu. mesenteroides and Lac. plantarum was the main acidifying organism. Total viable count increased rapidly in the beginning of fermentation and reached its maximum number at optimum ripening time and then decreased slowly as the acidity of Kimchi increased. While the total aerobic bacteria and fungi decreased during Kimchi fermentation, the yeast increased significantly at lower temperature.

• Microbiology and Biotechnology Letters
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• v.33 no.2
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• pp.106-111
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• 2005

To investigate the substrate variety of a putative non-metal dependent isomerase, the tagatose-6-phosphate isomerase (E.C. 5.3.1.26) structural genes (lacB; 510bp and lacA; 430bp) of Staphylococcus aureus were subcloned and co-expressed. Based on the substrate configuration, various aldoses were surveyed for substrate of ketose isomerization. Among the 10 aldoses tested, D-ribose and D-allose were isomerized by the enzyme. The subunit A and B showed more than $95\%$ activity for D-ribose and $75\%$ for D-allose in the presence of 1mM EDTA compared with non-EDTA conditions, which implying tagatose-6-phosphate isomerase is a non-metal dependent isomerase. Each of subunit A or subunit B alone showed no activity for any of the substrates tested. The affinity constant ($K_m$) of tagatose-6-phosphate isomerase against D-ribose and D-allose were 26 mM and 142 mM, respectively.

• The Korean Journal of Physiology and Pharmacology
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• v.15 no.5
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• pp.251-258
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• 2011

Here we have investigated how lactosylceramide (LacCer) modulates gene expression of adhesion molecules in TNF-${\alpha}$ and IFN ${\gamma}$ (CM)-stimulated astrocytes. We have observed that stimulation of astrocytes with CM increased the gene expression of ICAM-1 and VCAM-1. D-Threo-1-phenyl-2-decanoylamino-3-morpholino-1-propanol (PDMP) and N-butyldeoxynojirimycin (NBDNJ), inhibitors of glucosylceramide synthase (GLS) and LacCer synthase (galactosyltransferase, GalT-2), inhibited the gene expression of ICAM-1 and VCAM-1 and activation of their gene promoter induced by CM, which were reversed by exogenously supplied LacCer. Silencing of GalT-2 gene using its antisense oligonucleotides also attenuated CM-induced ICAM-1 and VCAM-1 expression, which were reversed by LacCer. PDMP treatment and silencing of GalT-2 gene significantly reduced CM-induced luciferase activities in NF-${\kappa}B$, AP-1, GAS, and STAT-3 luciferase vectors-transfected cells. In addition, LacCer reversed the inhibition of NF-${\kappa}B$ and STAT-1 luciferase activities by PDMP. Taken together, our results suggest that LacCer may play a crucial role in the expression of ICAM-1 and VCAM-1 via modulating transcription factors, such as NF-${\kappa}B$, AP-1, STAT-1, and STAT-3 in CM-stimulated astrocytes.

• Journal of Mushroom
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• v.19 no.1
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• pp.33-40
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• 2021

The genome sequence of various Flammulina species has recently been reported, thereby revealing a diverse genetic repertoire. In this study, we identified laccase genes and analyzed their structural characteristics in Flammulina elastica (F. elastica) genome. Through genome analysis and bioinformatics approaches, three laccase genes (Fe-lac1, -lac2, and -lac3) were identified, ranging from 1,548 to 1,602 bp in length. These genes contained a copper ion-binding region with ten histidine residues and one cysteine residue and a disulfide bond-forming region with four cysteine residues. Full-length cDNA sequencing analysis revealed that laccase genes contain 12 to 16 introns and signal peptides between 17 and 22 bp in the N-terminus. Structural characterization of the laccase genes identified in this study should help in better understanding the biomass decomposition of F. elastica.

• KSBB Journal
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• v.10 no.1
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• pp.38-45
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• 1995

The expression of Aspergillus nidulans glyceraldehyde-3-phosphate dehydrogenase (gpdA) and trpC promoters in A. oryzae were compared using E. coli lacZ gents fusions. The specific activities of the expressed E. coli $\beta$-galactosidase in A. oryzae transformants containing the A. nidulans gpdA promoter were around 2,000 units per ug of protein. The specific activities of transformants containing the A. nidulans trpC promoter were very low, ranging from 10.5 to 52.3 units per ug of protein. These results showed that the expression of the A. nidulans gpdA promoter in A. oryzae was approximately 70 times greater than the A. nidulans trpC promoter. In western blot analysis, immunoreactive bands of a imlilar molecular weight as the E. coli $\beta$-galactosidase were observed in A. oryzae carrying the gpdA-lacZ fusion and to a lesser intensity in those carrying the tvpC-lacZ fusion. Southern analysis showed that the higher expression of the gpdA-lacZ fusion as compared to the trpC-lacZ fusion was not due a greater number of integrated plasmids.

• Korean Journal of Agricultural Science
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• v.48 no.4
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• pp.965-973
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• 2021

The intention of this research is to analyze the effects of lactulose (LAC) supplementation on the growth performance, nutrient digestibility, microbial shedding, and fecal noxious gas emissions on weaning pigs in a 42-day trial. Based on the initial body weight and sex, a total of 255 piglets (21 day old) were randomly allocated into one of three dietary treatments with 15 replications and five pigs (two female and three male) per pen. The dietary treatments were as follows: a corn-soybean meal-based basal diet (CON) supplemented with 0, 1, and 2 g·kg^-1 of LAC. During phase 1, significant (p < 0.05) increases in the average daily feed intake and average daily gain (ADG) were observed, whereas during phase 2 and overall experimental period, significant improvements (p < 0.05) in the body weight, ADG, and gain to feed ratio were observed in pigs fed a graded level of LAC compared to those fed the CON diet. Additionally, dietary LAC supplementation significantly improved (p < 0.05) the nutrient digestibility dry matter, nitrogen, and gross energy in both phase 1 and phase 2. Moreover, the inclusion of LAC supplementation significantly increased (p < 0.05) the fecal Lactobacillus counts and reduced (p > 0.05) the E. coli counts in pigs. Furthermore, LAC supplementation reduced (p > 0.05) fecal ammonia and hydrogen sulfide gas emissions during phase 2. The results here indicate that the addition of lactulose at 1 g·kg^-1 and/or 2 g·kg^-1 would be optimal to improve the performance outcomes of weaning piglets.

• Journal of Ginseng Research
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• v.30 no.2
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• pp.88-94
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• 2006

Ginseng as a raw material for production of probiotic ginseng product by lactic acid bacteria (LAB) was evaluated in this study. Either white ginseng (WG) or red ginseng (RG) (1% or 5%, w/v) were directly inoculated with a 24 hold seed culture of twenty seven substrains of four different LAB ($1.0{\times}10^6CFU/ml$); Lactobacillus spp., Streptococcus/Enterococcus spp., Leuconostoc/Lactococcus spp. and Bifidobacterium spp., and incubated at $37^{\circ}C$ for 24 or 48 h. Among 27 kinds of LAB, seven substrains of Lactobacillus (MG208, MG311, MG315, MG501, MG501C, MG505, MG590) and one Bifidobacterium (MG723) were selected based on their dose dependent stimulation of the growth of LAB in the presence of ginseng and changes in pH, acidity and viable cell counts during fermentation were examined. Lactobacillus MG208 specifically was found to show the best growth on 5% RG and reached nearly $14.0{\times}10^8CFU/ml$ after 48 h of fermentation and produced the titratable acidity as $0.84{\pm}0.02%$, whereas the pH was significantly lowered from $6.80{\pm}0.01\;to\;3.42{\pm}0.02$. These results indicated that ginseng can be an appropriate material to prepare the fermentation product by several strains of LAB. Therefore we should further check whether probiotic ginseng product may have synergistic health benefits of both probiotics and ginseng to serve for vegetarians and lactose-allergic consumers.