• Fisheries and Aquatic Sciences
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• v.2 no.1
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• pp.44-51
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• 1999

Proteolytic bacteria isolated from fermented anchovy jeotkal were immobilized in capsule type with $0.8\%$ sodium alginate and $CaCl_2/carboxymethyl$ cellulose (CMC). For making the immobilized capsule, the optimal concentration of both $CaCl_2$ and CMC, with respect to the membrane hardness and the growth of proteolytic bacteria in capsule, were $2.0\%$ at following conditions: flow rate of $CaCl_2/CMC$ solution and cell suspension were respectively 3.54 ml/min and 0.15 ml/min when inside diameter of inner and outer capillary tube in immobilizing apparatus were 0.32mm, 0.74mm, respectively. The density of proteolytic bacteria in capsule reached maximum, i.e. $10^8-10^9cells$/capsule during culture under optimal conditions in TPY broth, and these were $10^2-10^4$ times higher than these of before culture. During culture of proteolytic bacteria immobilized in capsule type (PBImC) for 72hrs, few growing cells were lost in the outer medium.

• Fisheries and Aquatic Sciences
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• v.2 no.1
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• pp.36-43
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• 1999

A study on the hydrolysis of anchovy using proteolytic bacteria isolated from anchovy jeotkal (a salt-fermented fish) was carried out to develop a rapid process of liquefied anchovy jeotkal. Five kinds of proteolytic bacteria, such as Staphylococcus sp.-l, Photobacterium sp., Volcaniella sp., Staphylococcus sp.-2 and Bacillus sp., were isolated from the anchovy jeotka1 that fermented with $20\%$ NaCl at room temperature for 2 months. Those grew well at $40^{\circ}C$, pH 7.0 on TPY broth with $2.0\%$ NaCl. The optimal hydrolysis temperature, pH, time and proteolytic bacteria densities for hydrolysis of minced anchovy were$40^{\circ}C$, 7.0, 6 hours and $1.8\times10^8$ cells/g raw anchovy, respectively.

• Journal of Microbiology
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• v.41 no.2
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• pp.73-77
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• 2003

Four proteolytic bacteria were isolated and identified from a rotating biological contactor based on Bacillus. The four isolates, Ni 26, 36, 39 and 49 were identified as B. vallismortis, B. subtilis, Aeromonas hydrophila and B. amyioliquefaciens, respectively, based on their biochemical properties and 16S rDNA sequence analyses. The optimal proteolytic activity was observed in the temperature and pH ranges of 40-70$^{\circ}C$ and 8.0-8.5, respectively. The proteolytic activities of all the isolates were partially inhibited by phenylmethylsulfonylfluoride (PMSF), and the isolates Ni 26, Ni 39 and Ni 49 were inhibited by the metalloprotease inhibitor, 1,10-phenanthroline. Zymographic analyses of the culture supernatants revealed the presence of at least two pretenses in all isolates.

• Journal of Dairy Science and Biotechnology
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• v.40 no.2
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• pp.86-91
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• 2022

Chryseobacterium mulctrae KACC 21234^T is a novel species isolated from raw bovine milk. Psychrotrophic bacteria are considered contaminants and are hypothesized to originate from the environment. In this investigation, the C. mulctrae KACC 21234^T genome was determined to be 4,868,651 bp long and assembled into four contigs with a G+C ratio of 33.8%. In silico genomic analyses revealed the presence of genes encoding proteases (endopeptidase Clp, oligopeptidase b, carboxypeptidase) and lipases (phospholipase A(2), phospholipase C, acylglycerol lipase) that can catalyze the degradation of the proteins and lipids in milk, causing its quality to deteriorate. Additionally, antimicrobial resistance and putative bacteriocin genes were detected, potentially intensifying the pathogenicity of the strain. The genomic evidence presented highlights the need for improved screening protocols to minimize the potential contamination of milk by proteolytic and lipolytic psychrotrophic bacteria.

• Asian-Australasian Journal of Animal Sciences
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• v.33 no.1
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• pp.100-110
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• 2020

Objective: The objective of this study was to isolate proteolytic microorganisms and evaluate their effects on proteolysis in total mixed ration (TMR) silages of soybean curd residue. Methods: TMRs were formulated with soybean curd residue, alfalfa or Leymus chinensis hay, corn meal, soybean meal, a vitamin-mineral supplement, and salt in a ratio of 25.0: 40.0:30.0:4.0:0.5:0.5, respectively, on a basis of dry matter. The microbial proteinases during ensiling were characterized, the dominate strains associated with proteolysis were identified, and their enzymatic characterization were evaluated in alfalfa (A-TMR) and Leymus chinensis (L-TMR) TMR silages containing soybean curd residue. Results: Both A-TMR and L-TMR silages were well preserved, with low pH and high lactic acid concentrations. The aerobic bacteria and yeast counts in both TMR silages decreased to about 10⁵ cfu/g fresh matter (FM) and below the detection limit, respectively. The lactic acid bacteria count increased to 10⁹ cfu/g FM. The total microbial proteinases activities reached their maximums during the early ensiling stage and then reduced in both TMR silages with fermentation prolonged. Metalloproteinase was the main proteinase when the total proteinases activities reached their maximums, and when ensiling terminated, metallo and serine proteinases played equally important parts in proteolysis in both TMR silages. Strains in the genera Curtobacterium and Paenibacillus were identified as the most dominant proteolytic bacteria in A-TMR and L-TMR, respectively, and both their proteinases were mainly with metalloproteinase characteristics. In the latter ensiling phase, Enterococcus faecium strains became the major sources of proteolytic enzymes in both TMR silages. Their proteinases were mainly of metallo and serine proteinases classes in this experiment. Conclusion: Proteolytic aerobic bacteria were substituted by proteolytic lactic acid bacteria during ensiling, and the microbial serine and metallo proteinases in these strains played leading roles in proteolysis in TMR silages.

• Food Science of Animal Resources
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• v.30 no.3
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• pp.443-448
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• 2010

Casein phosphopeptide (CPP) enhances calcium absorption in humans. Lactic acid bacteria (LAB) are capable of synthesis of cell-surface proteinase, which can hydrolyze milk protein and release several types of peptides in the medium. This study was conducted to characterize proteinase of LAB and to evaluate the CPP production from bovine milk. The content of CPP of milk produced by cell-free extract of LAB was determined based on the quantity of decomposed peptide from casein using the O-phthaldialdehyde (OPA) method. The proteolytic activity of LAB was assayed using fluorescein isothiocyanate (FITC)-labeled casein. Casein appeared to be a better substrate than whey proteins for extracellular proteinases of LAB. During fermentation, milk proteins were hydrolyzed by extracellular proteinase of LAB, resulting in an increase in the amount of free $NH_3$ groups. Overall, the results presented here indicate that CPP produced by LAB may be a promising material for novel applications in the dairy industry.

• Restorative Dentistry and Endodontics
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• v.22 no.1
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• pp.76-92
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• 1997

Porpilyromonas endodontalis is specifically involved in endodontic infections. The bacterium can be isolated almost exclusively only from infected rool canals. P. gingivalis also has been implicated in endodontic infection. Pathogemcity of P. gingival is is attributed to a variety of virulence factors, especially proteases, produced by the bacterium. Importance of P. endodontalis in endodontic infection has been revealed. However, the pathogenic property of P. endodontalis has not been extensively studied. The present study was undertaken to characterize the proteolytic activity of P. endodontalis and compare the activity with that of P. gingivalis which has the most potent and diverse proteases among oral bacteria. For this purpose, culture supematants(SUP) and cell extracts(CE) were obtained from these two bacteria and were subjected to zymography using 15% polyacrylamide gel copolymerized with gelatin, type I, IV collagens or albumin. Hydrolysis of the collagens was further investigated by the cleavage assay using native type I and IV collagens in solution-phase. The results were as follows: 1. P. endodontalis apparently has a proteolytic activity that is comparable with that of P. gingivalis. 2. SUP and CE obtained from P. endodontalis and P. gingival is showed the strongest activity for gelatin, followed by type I and IV collagens, and albumin. 3. In the zymography, no noticeable difference in proteolytic activity for gelatin and albumin between the SUP and CE was observed, but in the cleavage assay using native collagens, the SUP showed a stronger collagenolytic activity than the CE. 4. The gelatinolytic activity of both the SUP and CE from these two bacteria was diminished in the presence of $CaCl_2$ or reducing agents such as ${\beta}$-mercaptoethanol and dithiothreitol(DTT). 5. Type I(calf skin and human placenta) collagenolytic activity of P. endodontalis and P. gingivalis was reduced by DTT but not affected by $CaCl_2$. The inhibitory effect of DTT, however, was reduced to some extent by $CaCl_2$. 6. Type IV collagenolytic activity of these two bacteria was not affected by $CaCl_2$ but increased to some extent in association with the reducing agents. 7. Hydrolysis of albumin by P. endodontalis and P. gingivalis was demonstrated only in the presence of the reducing agents. The overall results indicate that with respect to proteolytic activity, P. endodontalis appears to be as potent as P. gingivalis, or maybe more, and its proteolytic characteristic is similar to that of P. gingivalis. This suggests that P. endodontalis has so potent proteolytic activity that can participate by itself in endodontic infections and apical periodontitis, causing tissue destruction.

• Nuclear Engineering and Technology
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• v.1 no.1
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• pp.17-22
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• 1969

English sole (Parophrvs vetulus) fillets packaged in polymylar bags were irradiated at 500 Krad, using a Cobalt-60 irradiator and the accumulation of spoilage indices substances and bacterial growth in the irradiated and unirradiated samples were measured during 36 days of storage at 0-2$^{\circ}C$. A casein agar plate technique was developed for a direct enumeration of proteolytic bacterial population, thus enabling the determination of relative proportion of proteolytic bacteria in the total microflora at each storage interval. Irradiation at 500 Krad resulted in a ten fold reduction of microflora and throughout the storage period the level of microflora lagged behind that of the unirradiated, by as much as one thousand fold. This was accompanied by a remarkable suppression of TVB and TMA accumulation in the irradiated, never reaching a spoliage level. Proteolytic bacterial population also was reduced to below one per cent of the total viable count and remained so throughout the storage period, while proteolytic bacteria in the unirradiated increased proportionately with the storage, comprising 85.5% of the total microflora by the twenty-second day. This selective removal of proteolytic bacteria must account for the reduced rate of proteolysis occurred in the irradiated during the storage.

• Journal of Microbiology and Biotechnology
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• v.4 no.4
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• pp.305-315
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• 1994

Nineteen strains of bacteriocin-producing lactic acid bacteria were isolated from 432 Kimchi samples, and identified by the comprehensive biochemical and morphological tests verifying their cellular fatty acid composition. Using partially purified bacteriocins from these isolates, their inhibitory activities against other lactic acid bacteria and some pathogens, and sensitivity to enzyme and heat treatments were tested. The isolates were identified as Lactobacillus plantarum (2 strains), L curvatus (2 starins), L brevis (2 strains), Enterococcus faecium (6 strains), Leuconostoc mesenteroides subsp. mesenteroides (1 strain) and Lactobacillus sp. (6 strains). The bacteriocins produced by E. faecium strains provided the broadest spectrum of inhibition, affecting against other Gram-positive bacteria including lactic acid bacteria and health-threatening bacteria such as Clostridium perfringens and Listeria monocytogenes. The bacteriocins of Lactobacillus sp., L plantarum and L brevis strains were capable of inhibiting many strains of the lactic acid bacteria, whereas those of L curvatus and L mesenteroides subsp. mesenteroides strains were only inhibitory to a few strains. Generally, the inhibitory activities of both E. faecium and Lactobacillus sp. strains were greater than those of other producer strains. The bacteriocins from the isolates were sensitive to several proteolytic enzymes, and those of L curvatus and L mesenteroides subsp. mesenteroides were also sensitive to lipase and $\alpha$-amylase as well as to proteolytic enzymes. The bacteriocins from the strains of Lactobacillus sp. and a strain of L. brevis were resistant to autoclaving.

• Journal of Dairy Science and Biotechnology
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• v.30 no.2
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• pp.119-129
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• 2012

Lactic acid bacteria (LAB) have been used as starter cultures in the manufacturing processes of fermented dairy products such as cheese and yogurt. LAB have a proteolytic system to use the nitrogen source from milk for their growth. The proteolytic system involved in casein utilization provides cells with essential amino acids during growth in milk and is also of industrial importance, because of its contribution to the development of the organoleptic properties such as flavor of fermented milk products. In the most extensively studied LAB, Lactococcus lactis, the main features of the proteolytic system comprise 3 groups. The first is proteinase, which initially cleaves the milk protein to peptides. The second group consists of transport systems for the internalization of oligopeptides, which are involved in the cellular uptake of small peptides and amino acids. The third group, peptidases in the cell, cleaves peptides into smaller peptides and amino acids. This review is to provide the information about the proteolytic system of LAB.