1,720,965 research outputs found
Prevalence of Vibrio spp. Infection in Shrimp and Bio-control Using Bacteriophages Isolated from Shrimp Farms in Kuching
Get PDFShrimp farming, a highly profitable sector in global aquaculture, has seen remarkable growth in recent years, with global shrimp consumption projected to reach US$ 74 billion by 2032. This increasing demand and the expansion of farming operations, including in Sarawak, Malaysia, highlight the sector's potential. However, the industry faces significant challenges, particularly the prevalence of vibriosis, a bacterial infection caused by Vibrio species. Contamination of food products has also increased the risk of vibriosis in humans. The widespread use of antibiotics to combat this disease has led to the rapid emergence of antimicrobial resistance (AMR) bacteria. This study presents a comprehensive investigation into the surveillance profiles and bio-control of Vibrio spp. isolated from a shrimp farm in Sarawak, Malaysia. A total of 48 (n=48) samples, including water, sediment, shrimp, and effluent, were collected from two ponds throughout the production cycle. The prevalence and quantification of Vibrio species were assessed by implementing the MPN-multiplex polymerase chain reaction (PCR) method. The findings revealed high prevalence rates, with Vibrio parahaemolyticus being the most prevalent species (97.92%), followed by Vibrio cholerae (47.92%) and Vibrio alginolyticus (25.0%). The MPN values of V. parahaemolyticus were as high as >1,100 MPN/mL or MPN/g in the water, sediment, and shrimp samples of both ponds, which are the highest among the three Vibrio species. The MPN values of V. cholerae and V. alginolyticus remained less than 1,100 MPN/mL or MPN/g in water, sediment, and shrimp samples towards the end sampling period despite starting high initially. Notably, V. parahaemolyticus exhibited an increasing trend from stocking to harvesting periods, whereas V. cholerae and V. alginolyticus showed a decreasing trend. Further analysis involved antibiotic susceptibility testing of 30 (n=30) Vibrio spp. isolates by using 18 antibiotics, revealing resistance to at least two antibiotics. Antibiotics Ceftazidime, Meropenem, Gentamicin, Tetracycline, Nalidixic acid, Norfloxacin, Ciprofloxacin, and Chloramphenicol were 100% effective against all isolates of V. parahaemolyticus, V. cholerae, and V. alginolyticus. Meanwhile, 100% of V. parahaemolyticus and V. alginolyticus isolates were completely resistant to Penicillin G and Bacitracin, whereas 100% of V. cholerae isolates exhibited resistance to Penicillin G. The MAR indices of the isolates ranged from 0.11 to 0.39. In response to the escalating antibiotic resistance, bacteriophages emerged as promising alternatives. Two novel myophages, EniLVP01 and EniLVP02, targeting V. parahaemolyticus were isolated, characterised, and found to exhibit narrow host ranges and large burst sizes of 110 and 144 phages per infected cells, respectively. Notably, they effectively prevented and reduced bacterial biofilms. In the biofilm prevention, the absorbances were reduced from 0.592 ± 0.055 to 0.218 ± 0.039 for EniLVP01 and to 0.204 ± 0.016 for EniLVP02. Meanwhile, in the biofilm destruction assay, the mixture treated with the phage lysate of EniLVP01 and EniLVP02 showed an absorbance of 0.139 ± 0.009 and 0.174 ± 0.026, respectively, compared to the untreated samples with an absorbance of 0.843 ± 0.0029. Both phages also demonstrated promising efficacy in reducing V. parahaemolyticus counts on retail shrimp matrices, with a bacterial reduction of 98% achieved using a cocktail both phages. Phage EniLVP01 and EniLVP02 exhibited stability across a wide range of pH (pH 4.0 – 9.0) and temperature (28 °C - 65 °C) conditions. Genomic sequencing revealed high similarity between EniLVP01 and EniLVP02, suggesting they may belong to the same species in the Caudovirales order or are very closely related despite originating from different sources. Importantly, the absence of lysogeny-related, antibiotic, and virulence genes in their genomes supports their safety for therapeutic use. These findings represent a significant advancement in understanding the potential of phage therapy in the battle against bacterial infections and antibiotic resistance issues within Malaysia generally, and within Sarawak specifically
Screening and Biodegradation of Polycyclic Aromatic Hydrocarbons by Indigenous Endophytic Fungi
Get PDFPhenanthrene is a type of polycyclic aromatic hydrocarbon (PAH). It is an organic pollutant that exists persistently in the environment, resulting mainly from anthropogenic activities. Out of the 24 different fungi that had been successfully isolated from water hyacinth (Eicchornia crassipes), 5 fungal isolates showed the ability to degrade phenanthrene. Isolates EC08 and EC22, showed higher rate of phenanthrene degradation as compared to isolates EC04, EC13, and EC18. Percentage of phenanthrene degradation of EC08 and EC22 after 7 days was shown to be 8.26% and 14.19%, respectively. All five isolates showed the presence of manganese peroxidase (MnP), lignin peroxidase (LiP), and laccase (Lacc) activities in the presence of phenanthrene. The magnitude of the enzyme activities did not correlate with the percentage of phenanthrene degradation by the fungi. This suggests that other enzymes apart from the ligninolytic enzymes might be involved in the degradation pathways, and that the phenanthrene degradation involves a complex multienzymatic system. The physical and chemical parameters that can affect the growth of fungi and the rate of phenanthrene degradation were studied. It was observed that, each of the isolate showed different preferences in the pH of the growth media, the supplemental carbon, as well as the supplemental nitrogen. Identification of the five isolates was done based on their morphology as well as through molecular analysis. Through the analysis, isolates EC04, EC08, and EC22 were identified as Phlebia acanthocystis, Penicillium pinophilum, and Aspergillus versicolor respectively, while isolates EC13 and EC18 were identified as Inonotus pachyphyleous T61 and Inonotus pachyphloeus RS1, respectively.
Keywords: Phenanthrene, degradation, ligninolytic enzymes, manganese peroxidase, lignin peroxidase, laccas
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Isolation, characterization, and application of a novel Vibrio parahaemolyticus bacteriophage from retail shrimp in Sarawak, Malaysia
No full textShrimp farming, a highly profitable sector in global aquaculture, has seen remarkable growth in recent years.
This increasing demand and the expansion of farming operations, including in Sarawak, Malaysia, highlight the
sector’s potential. However, the industry faces significant challenges, particularly the prevalence of vibriosis, a
bacterial infection caused by Vibrio species. Contamination of food products has also increased the risk of
vibriosis in humans. The widespread use of antibiotics to combat this disease has led to the rapid emergence of
antimicrobial resistance (AMR) bacteria. This study specifically focuses on the isolation and characterization of
phage EniLVP02, a novel bacteriophage with the potential to combat V. parahaemolyticus infections. EniLVP02
was successfully isolated from shrimp purchased at a retail market and exhibited strong lytic activity against
V. parahaemolyticus strains. Structural analysis categorized EniLVP02 within the Straboviridae family, belonging
to the class Caudoviricetes. The phage displayed a narrow host range and lytic nature only towards
V. parahaemolyticus strains isolated from the Telaga Air shrimp farm. Phage EniLVP02 exhibited long latent
period of 120 min and large burst size of 144 phages per infected cells. Stability studies revealed EniLVP02’s
resilience across various pH (pH 4.0–9.0) and temperature (28 ◦C–65 ◦C) conditions, particularly at physiological
temperatures. Comparative genome analyses indicated its distinct evolutionary relationship and low homology
with other Vibriophages, suggesting its novelty. EniLVP02 demonstrated significant potential in biofilm prevention and destruction, with absorbance (OD600 nm) reduction from 0.592 ± 0.055 to 0.204± 0.016 and from
0.843± 0.003 to 0.174± 0.026 respectively. Moreover, in the treatment of V. parahaemolyticus-contaminated
shrimp meat, EniLVP02 effectively inhibit bacterial concentrations by 75.2 % at room temperature and 16.2 % at
4 ◦C after 24 h. Genomic sequencing revealed low similarity between EniLVP02 with other phages, suggesting its
novelty. Importantly, the absence of lysogeny-related, antibiotic resistance, and virulence genes in its genome
supports EniLVP02’s safety for therapeutic use. This study underscores the importance of exploring phages from
retail food products for therapeutic applications and highlights the promising attributes of phage EniLVP02 in
combating V. parahaemolyticus infections in aquaculture. Further investigations on its compatibility with other
phages and application in diverse food matrices are warranted to assess its full potential
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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