• Journal of Microbiology and Biotechnology
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• 제27권3호
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• pp.471-479
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• 2017

White spot syndrome virus (WSSV) is a major threat to the shrimp farming industry and so far there is no effective therapy for it, and thus early diagnostic of WSSV is of great importance. However, at the early stage of infection, the extremely low-abundance of WSSV DNA challenges the detection sensitivity and accuracy of PCR. To effectively detect low-abundance WSSV, here we developed a pre-amplification PCR (pre-amp PCR) method to amplify trace amounts of WSSV DNA from massive background genomic DNA. Combining with normal specific PCR, 10 copies of target WSSV genes were detected from ${\sim}10^{10}$ magnitude of backgrounds. In particular, multiple target genes were able to be balanced amplified with similar efficiency due to the usage of the universal primer. The efficiency of the pre-amp PCR was validated by nested-PCR and quantitative PCR, and pre-amp PCR showed higher efficiency than nested-PCR when multiple targets were detected. The developed method is particularly suitable for the super early diagnosis of WSSV, and has potential to be applied in other low-abundance sample detection cases.

• 환경생물
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• 제21권4호
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• pp.342-351
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• 2003

The southern rough shrimp Trachysalambria curvirostris (Stimpson) was monthly sampled from the coastal area of Yeosu, Korea from June 2000 to May 2001 and its stomach contents were investigated. Mysids and amphipods were the most dominant prey, comprising >40% of the diet in both % occurrence and % abundance. In particular, mysids were most important food without regard to seasons, size classes, or sexes. The abundance and occurrence composition of food items showed a seasonal fluctuation: mysids and amphipods were the predominant prey items in spring (33.8%), summer (41.1%), autumn (43.9%), and winter (49.2%). For small-sized shrimps (＞25 mm CL), mysids and amphipods consist of more than 45% of its food in both % abundance and % occurrence. For large-sized shrimps (>25 mm CL), these were clearly dominant. The quantities and items of food did not differ in both genders, which mainly fed on mysids and amphipods. The trophic diversity and equality of diet varied with seasons and size classes. The diet diversity for smaller shrimps was highest in spring, while that for the larger shrimp lowest in winter. Also, the mandibular structure of Trachysalambria curvirostris indicates that the species is carnivorous.

• Ocean and Polar Research
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• 제32권1호
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• pp.41-52
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• 2010

Daily samples were collected during summer in order to analyse changes in the mesozooplankton community and to identify the major environmental factors that may influence mesozooplankton abundance in Jangmok Bay. A single site in the bay was sampled 47 times from July to September 2003. Mesozooplankton community, hydrographic (watertemperature, salinity, dissolvedoxygen) and biological (chlorophyll-a, ciliates densities, Noctiluca scintillans densities) factors were determined. The mesozooplankton abundance varied remarkably from 954 to $14,816\;inds.\;m^{-3}$. The six taxa of Evadne tergestina, barnacle nauplii and cypris, Paracalanus parvus s.1., Acartia omorii, Penilia avirostris and Sagitta crassa dominated numerically, contributing 86% of total mesozooplankton abundance. Stepwise multiple linear regression analysis was applied to find correlation between environmental factors and fluctuation in the abundance of dominant species and mesozooplankton. A. omorii was significantly correlated with temperature and N. scintillans densities. E. tergestina was correlated with temperature, salinity, and ciliate densities, whereas P. avirostris was correlated with temperature and dissolved oxygen. Among the environmental factors, mesozooplankton abundance correlated most strongly with N. scintillans densities. Accordingly, N. scintillans may be a key player in controlling the fluctuation of mesozooplankton abundance as a strong competitor for same food resources.

• 해양환경안전학회지
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• 제20권3호
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• pp.259-269
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• 2014

The objectives of this study to determine seasonal changes in species composition and abundance of fish and decapod assemblage, and the relationships between environmental factors and their abundance in an eelgrass bed of Jindong Bay. A total of 26 fish species and 29 decapod species were collected by a small beam trawl from an eelgrass bed in Jindong Bay in 2002. The dominant fish species were Hexagrammos otakii, Pholis neulosa and P. fangi and these accounted for 48.4 % in the total number of individuals. Dominant decapod taxa were Palaemon macrodactylus, Charybdis japonica, Pagurus minutus and C. bimaculata. These were primarily small species or early juveniles of larger species. Species composition and abundance varied greatly showing a peak in the number of individuals in April and May, and peak biomass in fish in July and decapods in August. Catch rate was low in winter months both in fish and in decapod. Seasonal changes in the abundance of fishes and decapods corresponded with eelgrass biomass and abundance of food organisms indirectly.

• Journal of Microbiology and Biotechnology
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• 제33권2호
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• pp.219-227
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• 2023

Lettuce is one of the most consumed vegetables worldwide. However, it has potential risks associated with pathogenic bacterial contamination because it is usually consumed raw. In this study, we investigated the changes in the bacterial community on lettuce (Lactuca sativa L.) in Chungcheong-do, South Korea, and the prevalence of foodborne pathogens on lettuce in different seasons using 16S rRNA gene-based sequencing. Our data revealed that the Shannon diversity index showed the same tendency in term of the number of OTUs, with the index being greatest for summer samples in comparison to other seasons. Moreover, the microbial communities were significantly different between the four seasons. The relative abundance of Actinobacteriota varied according to the season. Family Micrococcaceae was most dominant in all samples except summer, and Rhizobiaceae was predominant in the microbiome of the summer sample. At the genus level, the relative abundance of Bacillus was greatest in spring samples, whereas Pseudomonas was greatest in winter samples. Potential pathogens, such as Staphylococcus and Clostridium, were detected with low relative abundance in all lettuce samples. We also performed metagenome shotgun sequencing analysis on the selected summer and winter samples, which were expected to be contaminated with foodborne pathogens, to support 16S rRNA gene-based sequencing dataset. Moreover, we could detect seasonal biomarkers and microbial association networks of microbiota on lettuce samples. Our results suggest that seasonal characteristics of lettuce microbial communities, which include diverse potential pathogens, can be used as basic data for food safety management to predict and prevent future outbreaks.

• Ocean and Polar Research
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• 제35권3호
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• pp.205-217
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• 2013

We investigated the population dynamics of Aurelia aurita in Sihwa Lake from April to October in 2009. Salinity ranged from 5.9 to 30.7 psu at the surface. Abundance of mesozooplankton ranged from 3 to 111,874 indiv. $m^{-3}$. Ephyrae occurred from April to May with the peak in abundance occurring on 17 April. Maximum density of ephyrae was observed near the power transmission towers that are known to be habitats of polyps. Mortality of ephyrae was lower than in other areas because of the abundant prey concentration and the absence of predators. Young medusae occurred from April to July with the peak in abundance occurring on 8 May. Adult medusae occurred from May to July with the peak in abundance on 25 June and they disappeared before the rainy season. Planula occurred only in May and June with the peak in abundance on 25 June. Growth rates of Aurelia aurita ranged from -0.06 to 0.34 $d^{-1}$, and decreased rapidly after May. The period in which adult medusa occurred was restricted, compared with those in other area in Korea (e.g., Masan Bay) and Japan (e.g., Tokyo Bay). In the period of this study, the available food was limited in June and salinity decreased to ca. 20 psu in May because of the beginning of the wet season. We assumed that the exceptionally short period of occurrence of the medusa may be a response of adults to changes in temperature, salinity or food limitation which leads to the precocious maturation of young medusa and the release of planula and that the brief occurrence of medusa was caused by an abrupt decrease in activity after the release of planula.

• Journal of Ecology and Environment
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• 제36권1호
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• pp.11-17
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• 2013

The life cycle of butterflies is closely related to the growth of food plants and, through a prolonged coevolutionary process, has undergone an ecological adaptation. So, it is important that control the egg-laying number and place to secure enough food plant by female adult to guarantee the survival of the larvae. To study whether oviposition control of the Luehdorfia puziloi takes into greater consideration food plant leaf biomass or leaf abundance, correlation among the egg cluster size, the leaf size, and the number of leaves around egg clusters was investigated. According to the results, the egg clusters size exhibited positive correlation with the leaf size of food plants on which eggs had been laid but did not do so with the number of surrounding leaves. In addition, the number of egg clusters laid exhibited positive correlation with the number of surrounding food plant leaves but not with the leaf size on which eggs had been laid. Consequently, for the Luehdorfia puziloi, the females' recognition of the leaf size seems to be the most important factor in the egg cluster size, and the number of egg clusters had positive correlation with food plant density per unit area.

• Journal of Ecology and Environment
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• 제32권3호
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• pp.183-189
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• 2009

This research focused on the effects of fragmentation on moth diversity in an agricultural land-scape by comparing moth species richness and abundance between hillocks and young secondary forests. We examined five sites from the southwestern part of South Korea: three sites from hillock forest and two from secondary forest. We collected moths bi-weekly from April to October for a 2-year period (2006-2007) with a UV light trap that usually attracts moths within 30 meters. Tree species richness and abundance in $20m{\times}20m$ plots at each moth sampling site showed a substantial difference in tree diversity between the two types of forest habitats. The total abundance and richness of moth species were higher in secondary forests (541 species with 4,998 individuals) than in hillock forests (423 species with 3,913 individuals), irrespective of the distance among the sites. An ordination analysis with NMDS showed that habitat is the most important factor of grouping sites. The food preferences of the dominant moth species i,n each habitat were closely related to the habitat type.

• 한국해양학회지
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• 제19권1호
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• pp.1-10
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• 1984

1975年 12月에서 1976年 5月 사이에 濠洲 Cronulla近海에서 實施한 가다랭이 漁業試驗時 採集한 浮游生物과 가다랭이 胃內容物의 造成 및 量的 相互關係性을 分析硏究 하였다. 가다랭이의 먹이생물의 造成과 豊度는 富裕生物의 그것들과 잘 一致하였으며 그 主要먹이 생물로서는 Nyctiphanes australis, brachyura幼生, 정어리種漁 및 Copepoda등임을 밝혔다. 가장 많은 가다랭이 漁獲은 富裕生物組成上 N. australis와 brachyura유생이 가장 豊富했던 1月과 2月에 있었다. 特히 Copepoda중의 Undinula vulgaris는 가다랭이의 먹이생물中 선택적 기호성먹이로서 가치가 큰 것으로 나타났다.

• Journal of Microbiology and Biotechnology
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• 제28권7호
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• pp.1168-1177
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• 2018

The aim of this study was to investigate the microbial community of three tannery wastewater treatment plants (WWTPs) involved in nitrification by Illumina MiSeq sequencing. The results showed that highly diverse communities were present in tannery wastewater. A total of six phyla, including Proteobacteria (37-41%), Bacteroidetes (6.04-16.80), Planctomycetes (3.65-16.55), Chloroflexi (2.51-11.48), Actinobacteria (1.91-9.21), and Acidobacteria (3.04-6.20), were identified as the main phyla, and Proteobacteria dominated in all the samples. Within Proteobacteria, Beta-proteobacteria was the most abundant class, with the sequence percentages ranging from 9.66% to 17.44%. Analysis of the community at the genus level suggested that Thauera, Gp4, Ignavibacterium, Phycisphaera, and Arenimonas were the core genera shared by at least two tannery WWTPs. A detailed analysis of the abundance of ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) indicated that Nitrosospira, Nitrosomonas, and Nitrospira were the main AOB and NOB in tannery wastewater, respectively, which exhibited relatively high abundance in all samples. In addition, real-time quantitative PCR was conducted to validate the results by quantifying the abundance of the AOB and total bacteria, and similar results were obtained. Overall, the results presented in this study may provide new insights into our understanding of key microorganisms and the entire community of tannery wastewater and contribute to improving the nitrogen removal efficiency.