• Journal of Microbiology and Biotechnology
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• v.1 no.3
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• pp.188-196
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• 1991

The ${\beta}-glucosidase$ was purified to homogeneity from the culture filtrate of P. verruculosum by column chromatography. The enzyme was a glycoprotein with a relative size of approximately 220 kDa with an isoelectric point of 4.8, which was composed of dimeric protein of 105 kDa. The enzyme was stable up to $60^{\circ}C$ and the presence of glycerol significantly increased its thermostability. The enzyme was found to hydrolyze both ${\beta}-aryl$ and ${\beta}-alkyl-glucosides$ in addition to ${\beta}-glucosyl$ glucose and catalyzed glucosyl transfer to cellobiose. The enzyme attacked laminarin in an exotype-like fashion. The apparent Km's of the enzyme toward cellobiose, laminaribiose, laminarin were 0.53 mM, 0.35 mM and 1.11 mM, respectively. Glucose and glucono-${\delta}-lactone$ were competitive inhibitors for the enzyme. Copper ($Cu^{2+}$), mercury ($Hg^{2+}$) and p-chloromercuribenzoate were strong inhibitors of the enzyme. The immunoblotting result revealed that one form of ${\beta}-glucosidase$ was biosynthesized, irrespective of carbon sources used. Polyacrylamide gel electrophoresis analysis of the in vitro translated product of total RNA from avicel grown mycelium established that the P. verruculosum ${\beta}-glucosidase$ precursor was approximately 95 kDa in size. The amino acid composition and N-terminal amino acid sequence are given.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.50 no.3
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• pp.243-249
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• 2017

Crabs are a popular seafood item. However, they can harbor many microorganisms, heavy metals, radioactivity, and benzo(a)pyrene, which are potential health risks to humans. The objective of this study was to assess the potential of swimming crabs for use in foods such as Ganjang-gejang, by measuring their sanitary biological and chemical properties. Viable microbial cell counts in swimming crab samples were $3.4{\times}10^2-6.7{\times}10^4CFU/g$, but no coliform, Escherichia coli, or pathogenic bacteria, such as Vibrio parahaemolyticus, Enterohemorrhagic E. coli, Listeria monocytogenes, Staphylococcus aureus, or Salmonella spp., were detected. Heavy metal concentrations in swimming crab samples were non-detectable to 0.112 mg/kg for total mercury, non-detectable to 0.435 mg/kg for lead, and 0.115-0.836 mg/kg for cadmium. Benzo(a)pyrene concentrations ranged from $0.025-0.060{\mu}g/kg$, and the volatile basic nitrogen content ranged from 8.7-15.6 mg/100 g. No radioactivity was detected in samples. These results suggest that swimming crabs are viable for use in seafood products.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.50 no.2
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• pp.120-129
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• 2017

This study assessed the safety of raw oysters Crassostrea gigas for consumption during processing in a processing plant. Bacterial contamination (e.g., viable cell counts, coliform groups, Escherichia. coli and pathogenic bacteria) and chemical contamination (e.g., heavy metals and shellfish toxins) were measured on raw oysters, a processing equipment, employees and work areas. No total mercury, lead, paralytic shellfish poison, diarrheic shellfish poison or norovirus was detected in any post-harvested oyster samples. However, the cadmium level ranged from 0.1-0.2 mg/kg. The viable cell count, E. coli and coliform group levels in post-harvested oysters ranged from 4.00-4.54 log CFU/g, ND-210 MPN/100 g and 110-410 MPN/100 g, respectively. The viable contaminating cell counts on employees, equipment and work areas were in the range of $0.90-3.46log\;CFU/100cm^2$. Airborne bacteria in the work areas ranged from 0.60 to 1.81 log CFU/plate/15 min. Thus, no significant health risks were detected in the processing plant.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.50 no.2
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• pp.130-138
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• 2017

This study examined chemical characterization in commercial dark-fleshed fish (mackerel Scomber japonicus, Japanese Spanish mackerel Scomberomorus niphonius, and Pacific herring Clupea pallasii) to determine their suitability for use as raw materials for seafood products. The volatile basic nitrogen (VBN), heavy metal, radioactivity, polychlorinated biphenyl (PCBs), benzo[a]pyrene, and histamine concentrations were measured. The VBN in all of the dark-fleshed fish was less than 20 mg/100 g, which is the limit for raw materials for seafood processing. Except for mackerel based on the lead (Pb) standards of the European Union (EU), Taiwan, and CODEX, and all fish based on the cadmium (Cd) standards for China and the EU, the commercial dark-fleshed fish were free from total mercury (Hg), Pb, and Cd based on domestic and foreign standards. The radioactivity, polychlorinated biphenyl (PCB), benzo[a]pyrene, and histamine concentrations of the commercial dark-fleshed fish all adhered to the domestic and foreign standards. The commercial dark-fleshed fish tested could all be used as raw materials for seafood products, except for some exported products.

• Korean Journal of Soil Science and Fertilizer
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• v.49 no.5
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• pp.524-530
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• 2016

Agricultural soils near or around industrial complexes can contain a certain amount of heavy metals that readily enter the food chain and negatively affect human health. Therefore, we conducted the study to investigate the distribution of selected heavy metals, including arsenic (As), cadmium (Cd), chromium (Cr), nickel (Ni), lead (Pb), mercury (Hg), and zinc (Zn), in farm-land soils around fifteen industrial complexes in the southwestern provinces, Korea. The concentrations of heavy metals in the soil samples were determined by the pseudo-total aqua regia (3 HCl : $1HNO_3$) digestion procedure. The heavy metal concentrations in most soils examined did not exceed the levels of Soil Contamination Warning Standard (SCWS) for agricultural lands (Region 1) presented in Soil Environment Conservation Law (SECL) established by Ministry of Environment (MOE), Korea. However, only one sampling site showed higher As amount ($27.1mg\;kg^{-1}$) than the SCWS level of As ($25mg\;kg^{-1}$). Pollution index (PI) for heavy metals did not exceed 1.0. The PI values were significantly positively correlated (p < 0.01) with the heavy metal concentrations. In particular, the values of correlation coefficient between the Cd and Pb concentrations and the PI values were higher than those estimated from other combinations, and thus the amounts of Cd and Pb in the agricultural soils highly affected the PI values for the heavy metals.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.50 no.4
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• pp.335-342
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• 2017

Oysters Crassostrea gigas are a globally popular shellfish for human consumption. As filter-feeding bivalve mollusks, oysters may harbor many microorganisms and chemicals that could pose potential human health risks. The objective of this study was to investigate the suitability of cultured oysters for raw consumption or use in seafood products by measuring concentrations of harmful microorganisms and chemicals in their flesh. Microbial concentrations in cultured oysters were found to be: $1.0{\times}10^2-6.0{\times}10^4CFU/g$ (viable cell counts), not detected $(ND)-5.4{\times}10^3CFU/g$ (coliform bacteria), $ND-1.3{\times}10^2CFU/g$ (E. coli), and $ND-4.6{\times}10^3CFU/g$ (Vibrio parahaemolyticus). Other pathogenic bacteria, including Enterohemorrhagic E. coli (EHEC), Listeria monocytogenes, Staphylococcus aureus, and Salmonella spp., were not detected in any samples. Heavy metal concentrations of cultured oysters were ND-0.239 mg/kg (total mercury), ND-1.091 mg/kg (lead), ND-0.968 mg/kg (cadmium). The concentrations of benzo(a)pyrene ranged from $0.280-0.880{\mu}g/kg$. Paralytic shellfish poison ranged from ND-0.58 mg/kg, while diarrhetic shellfish poison was not detected. No radioactivity was detected. These results suggest that oysters intended for raw consumption or use in seafood products should be subjected to chemical and biological controls.

• Journal of Food Hygiene and Safety
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• v.25 no.4
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• pp.310-319
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• 2010

This survey was conducted to monitor the food additives, heavy metals, and microbial contamination of the dried marine products like squids, pollacks, and shrimps, including jerked beef. They were purchased from supermarkets and traditional markets in Gwangju from February to December 2009. A total of 101 samples were tested. Sorbic acid, one of the additives, was detected in 29 samples of them (32.2%) and the contents were from 21.4 to 244.2 mg/kg. Among heavy metals, lead was detected, ranging from 0.000 to 0.594 mg/kg and cadmium, from 0.000 to 0.679 mg/kg and mercury, from 0.001 to 0.947 mg/kg. Sodium was detected, ranging from 0.6 to 1.7%. Aerobic bacteria were detected from 81 samples (80.2%), coliform bacteria, from 10 samples (9.9%) and Bacillus cereus, causing food poisoning, was isolated from 3 samples (3.0%).

• Safety and Health at Work
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• v.3 no.4
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• pp.257-267
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• 2012

Occupational neurotoxic diseases have become increasingly common in Taiwan due to industrialization. Over the past 40 years, Taiwan has transformed from an agricultural society to an industrial society. The most common neurotoxic diseases also changed from organophosphate poisoning to heavy metal intoxication, and then to organic solvent and semiconductor agent poisoning. The nervous system is particularly vulnerable to toxic agents because of its high metabolic rate. Neurological manifestations may be transient or permanent, and may range from cognitive dysfunction, cerebellar ataxia, Parkinsonism, sensorimotor neuropathy and autonomic dysfunction to neuromuscular junction disorders. This study attempts to provide a review of the major outbreaks of occupational neurotoxins from 1968 to 2012. A total of 16 occupational neurotoxins, including organophosphates, toxic gases, heavy metals, organic solvents, and other toxic chemicals, were reviewed. Peer-reviewed articles related to the electrophysiology, neuroimaging, treatment and long-term follow up of these neurotoxic diseases were also obtained. The heavy metals involved consisted of lead, manganese, organic tin, mercury, arsenic, and thallium. The organic solvents included n-hexane, toluene, mixed solvents and carbon disulfide. Toxic gases such as carbon monoxide, and hydrogen sulfide were also included, along with toxic chemicals including polychlorinated biphenyls, tetramethylammonium hydroxide, organophosphates, and dimethylamine borane. In addition we attempted to correlate these events to the timeline of industrial development in Taiwan. By researching this topic, the hope is that it may help other developing countries to improve industrial hygiene and promote occupational safety and health care during the process of industrialization.

• Advances in concrete construction
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• v.4 no.2
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• pp.71-88
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• 2016

Metakaolin, a dehydroxylated product of the mineral kaolinite, is one of the most valuable admixtures for high-performance concrete applications, including constructing reinforced concrete bridges and impact- and fire-resistant structures. Concretes produced using metakaolin become more homogeneous and denser compared to normal-strength concrete. Yet, these changes cause a change of volume throughout hardening, and increase the brittleness of hardened concrete significantly. In order to examine how the use of metakaolin affects the fracture and mechanical behavior of high-performance concrete we produced concretes using a range of water to binder ratio (0.42, 0.35 and 0.28) at three different weight fractions of metakaolin replacement (8%, 16% and 24%). The results showed that the rigidity of concretes increased with using 8% and 16% metakaolin, while it decreased in all series with 24% of metakaolin replacement. Similar effect has also been observed for other mechanical properties. While the peak loads in load-displacement curves of concretes decreased significantly with increasing water to binder ratio, this effect have been found to be diminished by using metakaolin. Pore structure analysis through mercury intrusion porosimetry test showed that the addition of metakaolin decreased the critical pore size of paste phases of concrete, and increasing the amount of metakaolin reduced the total porosity for the specimens with low water to binder ratios in particular. To determine the optimal values of water to binder ratio and metakaolin content in producing high-strength and high-performance concrete we applied a multi-objective optimization, where several responses were simultaneously assessed to find the best solution for each parameter.

• The Korean Journal of Ecology
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• v.11 no.1
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• pp.29-36
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• 1988

This present study has been carried out to examine the correlation between the distribution of the coliform bacterial plasmids and the viability test against heavy metals in the upper stream of Han river(Gapyung; clean water) and the its basin (Anyang Cheon; polluted water). And the distribution of plasmids were examined to be used as trophic indicator for analysis between the clean and polluted waters. 1. A total of 110 isolates were analyzed for the presence of plasmids by means of the boiling method and agarose gel techniques. Plasmids were significantly more frequent in the strains which had been isolated from the clean water (14.3%). Also, there were much higher multiplicity of plasmids at the polluted water(41.0%), compared with the clean water (33.0%). By the comparision between molecular weight of bacterial plasmids in the clean water and those of polluted water, there were no significant differences of the clean water from the polluted water, to such extent as 30.0%, 28.6%, respectively, in frequency for occurrence of high molecular weight plasmids iver 35.8% Mdal. 2. Each isolate was carried out the resistance test for mercury(10-5M), nickel(10-3M) and arsenic (0.1%). At the polluted site, the survival ability of the plasmid-carrying straings(Hg, 31.0%l Ni, 5.7%; As, 65.7%) was higher than that of the non plasmid-carrying strains(Hg, 12.1%; Ni, 3.0%; As, 54.6%). This trend was more remarkable in the clean site (plasmid-carrying strains: 16.7%,-,-). As a result it is suggested that plasmids could be used as an indicator of a certain types of water pollution. In addition, heavy metals might have inflyenced, some extent, to the distribution of plasmids in the environment which has been surveyed in the present study.