• Journal of Microbiology and Biotechnology
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• v.16 no.10
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• pp.1537-1543
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• 2006

A bacterial strain named HY-3 that produces a highly active extracellular protease was isolated from the digestive tract of a spider, Nephila clavata. The bacterium was a Gram-negative, oxidase-negative, catalase-positive, nonhalophilic, nitrate-reducing, facultative anaerobe. Transmission and scanning electron microscopies demonstrated that the isolate was non-spare-forming, straight, rod-shaped, and motile by peritrichous flagella. The G+C content of the DNA was 57.0 mol%. The isoprenoid quinone type was ubiquinone with 8 isoprene units (Q-8). The morphological and biochemical characteristics including the predominant fatty acid and phospholipids profiles placed the isolate HY-3 in the family Enterobacteriaceae. Further biochemical characterization and phylogenetic studies including determination of an almost complete 16S ribosomal DNA sequence suggested that the bacterium was closely related to the genus Serratia. DNA-DNA hybridization analysis revealed that this extracellular protease-producing strain belongs to Serratia proteamaculans, which is also known far its association with insects.

• International Journal of Industrial Entomology and Biomaterials
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• v.30 no.2
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• pp.40-44
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• 2015

To investigate whether Serratia marcescens (Enterobacteriales: Enterobacteriaceae) isolated from Protaetia brevitarsis seulensis (Coleoptera: Cetoniidae) acts as an opportunistic bacterium in peroral infection, the primary entomopathogenic bacteria Bacillus thuringiensis (Bacillales: Bacillaceae) and Paenibacillus popilliae (Eubacteriales: Bacillaceae) were added to sawdust to perform a bioassay experiment. We found that peroral infection caused by S. marcescens could be fatal beyond a concentration of $4{\times}10^8pfu/mL$ in $2^{nd}$ stage P. b. seulensis larvae and at $6{\times}10^8pfu/mL$ in $3^{rd}$ stage P. b. seulensis larvae. In particular, mortality resulting from a combination of P. popilliae and S. marcescens was markedly increased in $2^{nd}$ stage P. b. seulensis larvae. Therefore, we confirmed that mortality was increased when S. marcescens was infected together with other entomopathogenic bacteria, and that peroral infection itself can be fatal beyond certain concentrations.

• BMB Reports
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• v.28 no.2
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• pp.118-123
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• 1995

Biodegradative threonine dehydratase was purified to homogeneity from Serratia marcescens ATCC 25419 by streptomycin sulfate treatment, Sephadex G-200 gel filtration chromatography followed by AMP-Sepharose 4B affinity chromatography. The molecular weight of the purified enzyme was 118,000 by fast protein liquid chromatography using superose 6-HR. The enzyme was determined to be a homotetrameric protein with subunit molecular weights of 30,000 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The enzyme was inhibited by ${\alpha}-Keto$ acids and their derivatives such as ${\alpha}-ketobutyrate$, pyruvate, glyoxlyate, and phosphoenol pyruvate, but not by ${\alpha}-aminobutyrate$ and ${\alpha}-hydroxybutyrate$. The inhibition of the enzyme by pyruvate and glyoxylate was observed in the presence of AMP. The inhibitory effect of glyoxylate was decreased at high enzyme concentration, whereas the inhibition by pyruvate was independent of the enzyme concentration. The kinetics of inhibition of the enzyme by pyruvate and glyoxylate revealed a noncompetitive and mixed-type inhibition by the two inhibitors with respect to L-threonine and AMP, respectively.

• BMB Reports
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• v.28 no.2
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• pp.124-128
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• 1995

Biodegradative threonine dehydratase purified from Serratia marcescens ATCC 25419 was inactivated by the arginine specific modification reagent, phenylglyoxal (PGO) and the lysine modification reagent, pyridoxal 5'-phosphate (PLP). The inactivation by PGO was protected by L-threonine and L-serine. The second order rate constant for the inactivation of the enzyme by PGO was calculated to be 136 $M^{-1}min^{-1}$. The reaction order with respect to PGO was 0.83. The inactivation of the enzyme by PGO was reversed upon addition of excess hydroxylamine. The inactivation of the enzyme by PLP was protected by L-threonine, L-serine, and a-aminobutyrate. The second order rate constant for the inactivation of the enzyme by PLP was 157 $M^{-1}min^{-1}$ and the order of reaction with respect to PLP was 1.0. The inactivation of the enzyme by PLP was reversed upon addition of excess acetic anhydride. Other chemical modification reagents such as N-ethylmaleimide, 5,5'-dithiobis (2-nitrobenzoate), iodoacetamide, sodium azide, phenylmethyl sulfonylfluoride and diethylpyrocarbonate had no effect on the enzyme activity. These results suggest that essential arginine and lysine residues may be located at or near the active site.

• BMB Reports
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• v.34 no.3
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• pp.244-249
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• 2001

The anabolic acetolactate synthase III was purified to homogeneity from Serratia marcescens using DEAE-Sepharose, Phenyl-Sepharose, and hydroxylapatite column chromatography The native molecular weight of the enzyme was approximately 165 kDa. The enzyme is composed of two large and two small subunits with molecular weights of 64 and 15 kDa, respectively. The N-terminal sequence of the large and small subunit of the enzyme was Ser-Ala-Thr-Pro-Gln-Pro-Ser-Thr-Arg-Phe-Thr-Cys-Ala-Gln-Leu-Ile-Ala-His-Leu and Met-Leu-Gln-Pro-Gln-Asp-Lys-Pro-Gln-Val-Ile-Leu-Glu-Leu-Ala-Val-Arg-Asn-His-Pro-Gly-Val-Met-Ser-His-Val, respectively. The optimum pH and pI value were 7.5 and 5.5, respectively The $IC_{50}$ values were $20\;{\mu}M$ and $14\;{\mu}M$ for valine and herbicide SU7, respectively. The substrate specificity ratio, R value, was determined to be approximately 40, which suggests that this enzyme prefers the formation of $\alpha$-aceto-$\alpha$-hydroxybutyrate leading to the synthesis of isoleucine.

• Journal of Life Science
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• v.9 no.1
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• pp.54-57
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• 1999

We have got several clones from Serratia marcescens which stimulated the cells to use maltose as a carbon source in E. coli TP2139 (${\Delta}$lac, ${\Delta}$crp). One of the cloned genes, pCKB13, was further analyzed. In order to find whether the increased expression of the gene under the direction of maltose metabolism, we constructed several recombinant subclones. We have confirmed that the clone, pCKB13 codes Coenzyme A transferase gene by partial nucleotide sequencing in the terminal region. The enzyme activity of Coenzyme A transferase increased after introduction of the multicopy of the cloned gene in E. coli. The recombinant proteins expressed by multicopy and induction with IPTG, two polypeptide of 26-and 28-kDa, were confirmed by SDS-PAGE. Southern hybridization analysis confirmed that the cloned DNA fragment was originated from S. marcescens chromosomal DNA.

• Journal of Microbiology and Biotechnology
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• v.17 no.1
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• pp.74-80
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• 2007

An enantioselective lipase gene (esf) for the kinetic resolution of optically active (S)-flurbiprofen was cloned from the new strain Serratia marcescens ES-2. The esf gene was composed of a 1,845-bp open reading frame encoding 614 amino acid residues with a calculated molecular mass of 64,978 Da. The lipase expressed in E. coli was purified by a three-step procedure, and it showed preferential substrate specificity toward the medium-chain-length fatty acids. The esf gene encoding the enantioselective lipase was reintroduced into the parent strain S. marcescens ES-2 for secretory overexpression. The transformant S. marcescens BESF secreted up to 217kU/ml of the enantioselective lipase, about 54-fold more than the parent strain, after supplementing 3.0% Triton X-207. The kinetic resolution of (S)-flurbiprofen was carried out even at an extremely high (R,S)-flurbiprofen ethyl ester [(R,S)-FEE] concentration of 500 mM, 130 kU of the S. marcescens ES-2 lipase per mmol of (R,S)-FEE, and 1,000 mM of succinyl ${\beta}-cyclodextrin$ as the dispenser at $37^{\circ}C$ for 12h, achieving the high enantiomeric excess and conversion yield of 98% and 48%, respectively.

• Journal of Microbiology and Biotechnology
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• v.21 no.4
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• pp.430-437
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• 2011

The effects of the agitation and aeration rates on the production of serratiopeptidase (SRP) in a 5-L fermentor (working volume 2-l) were systematically investigated using Serratia marcescens NRRL B-23112. The dissolved oxygen concentration, pH, biomass, SRP yield, and maltose utilization were all continuously measured during the course of the fermentation runs. The efficiencies of the aeration and agitation were evaluated based on the volumetric mass transfer coefficient ($K_La$). The maximum SRP production of 11,580 EU/ml with a specific SRP productivity of 78.8 EU/g/h was obtained with an agitation of 400 rpm and aeration of 0.075 vvm, which was 58% higher than the shake-flask level. The $K_La$ for the fermentation system supporting the maximum production (400 rpm, 0.075 vvm) was 11.3 $h^{-1}$. Under these fermentor optimized conditions, kinetic modeling was performed to understand the detailed course of the fermentation process. The resulting logistic and Luedeking-Piret models provided an effective description of the SRP fermentation, where the correlation coefficients for cell growth, SRP formation, and substrate consumption were 0.99, 0.94, and 0.84, respectively, revealing a good agreement between the model-predicted and experimental results. The kinetic analysis of the batch fermentation process for the production of SRP demonstrated the SRP production to be mixed growth associated.

• Journal of Microbiology and Biotechnology
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• v.2 no.4
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• pp.231-236
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• 1992

A 5.8 kb chromosomal DNA fragment of Serratia marcescens ATCC 27117 including an extracellular serine protease gene was cloned in Escherichia coli. The cloned gene(pSMP18) caused specific excretion of the protease into the extracellular medium through the outer membrane of E. coli host cells. The protease purified from E. coli harboring pSMP18 was inactivated not by 100 mM EDTA but by 10 mM phenyl methyl sulfonyl flouride (PMSF). The molecular weight of the purified serine protease was about 66, 000 in the SDS-PAGE and the isoelectric point was approximately 5.7 in IEFㆍGel electrophoresis. The optimal pH and temperature for reaction of the purified serine protease were 9.5 and $45^\circ{C}$, respectively.

• Journal of Microbiology and Biotechnology
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• v.17 no.10
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• pp.1622-1628
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• 2007

We characterized the efficacy of an electrostatic precipitator (ESP) air-cleaner in reducing the concentration of Serratia marcescens in an enclosed space. We used an experimental room ($4.5{\times}3{\times}2.9\;m$) in which electrostatic air-cleaners were located. Two air-cleaners enhanced the equivalent ventilation rates in the chamber by about 3.3 air changes per hour (ACH) over the 2 ACH provided by the mechanical ventilation system. Natural die-off of the organisms provided an additional equivalent of 3 ACH, so that the total ventilation rate with the ESP air-ccleaners was 8.3 ACH. We also examined whether the ESP air-cleaners altered the deposition of Serratia marcescens aerosols on the experimental room surfaces. We did not find any significant differences in the number of colony forming units recovered from surfaces with and without the air-cleaners. We installed UV lights inside the ESPs and determined if UV light, in addition to electrical fields, increased the efficacy of the ESPs. The presence of UV light inside the ESP reduced S. marcescens aerosols by approximately 2 ACH. Finally, a box model indicates that the efficiency of the air-cleaner increases for both biological and nonbiological particles at ventilation rates of 0.2-1, which are typical for residential settings.