159 research outputs found

    Antimicrobial activities of some marine actinonycetes isolated from Malaysians waters

    Get PDF
    Marine actinobacteria were isolated from sediment and water samples from Malaysian waters using starch-yeast extract agar with seawater and marine agar (Difco) as a selective medium to isolate the actinomycetes. Ten isolates were selected from a collection of 300 isolates for further investigations based on colony morphology and pigment production. Genomic DNA from these isolates were extracted and subjected to polymerase chain reaction (PCR) to detect the presence of polyketide synthase type I (PKS-I) and non-ribosomal peptide syntethases (NRPS) [1]. Molecular identification was also performed using 16S rRNA gene partial sequencing. A phylogenetic tree based on 16S rRNA gene sequences was constructed using MEGA version 4 [2]. Scanning electron microscopy (SEM) was also performed on these isolates. Evaluation of antimicrobial activity was performed for isolates that exhibited the presence of both PKS-I and NRPS genes, and NRPS gene only. These isolates were challenged against of 5 Gram negative bacteria - E.coli, P. vulgaris, P. aeruginosa, P. mirabilis and S. marcescens; 3 Gram positive bacteria – Methicillin-resistant S. aureus (MRSA), B.subtilis and S. aureus; and 3 fungi - Candida parapsilosis, A. niger and Candida albican. The antimicrobial test was conducted by placing the isolates on trypticase soy agar (TSA) which had been inoculated with the test organisms. The antimicrobial activity was determined as a clear zone of inhibition surrounding the isolate. Eight isolates exhibited the presence of both PKS-I and NRPS genes of which 5 isolates belong to the genus Streptomyces, while another 2 isolates displayed only NRPS gene. Five isolates, mostly Streptomyces species demonstrated high antimicrobial activity against most of the test organisms which could be related to the presence of PKS-I and NRPS genes. Streptomycetes produce approximately 75% of commercially and medically useful antibiotics worldwide [3] therefore, it was anticipated that the Streptomycetes isolates in this study would display high antimicrobial activities. However, 2 isolates displayed no antimicrobial activity at all even though both genes were detected in them. Based on 16S rRNA gene sequencing, these isolates were presumed to belong to the genus Rhodococcus and Pseudonocardia. The presence PKS-I and NRPS genes might not necessarily result in antimicrobial activities since the function of polyketides is not confined to antimicrobial activities but may have other useful properties such as antihelmintics, anticancer or immunosuppressive agents [4].Nevertheless, early evaluation of these isolates based on the presence of both genes would allow to focus the screening of isolates that possessed high metabolic potential. In conclusion, Malaysian waters have the potential as important natural resources for exploration of marine actinomycetes that possess the ability to produce a relatively high rate of new antimicrobial bioactive agents

    Canopy Temperature Depression as an Effective Physiological Trait for Drought Screening

    Get PDF
    Water stress is a major production constraint in agriculture worldwide. Efforts to breed for drought tolerance are invariably hampered by the amount of time required to phenotype a large number of individuals and poor or inconsistent correlations and multiple mechanisms involved. Canopy temperature depression has emerged as a potential surrogate in view of substantial natural variation in crops as well as its correlation with yield. Based on the experimental findings two types of ideotype models based on CTD have been proposed as isohydric (“water saving”) and anisohydric (“water spending”). The isohydrics have advantage in the harsher environments, whereas the anisohydrics perform better under moderate/mild drought situations. Water savers have a shallow root system with intermediate root growth and thin roots. They are early and have high water use efficiency, reduced transpiration and limited leaf area and canopy biomass development and superior photosynthate remobilization to pod and grain. Contrary to this, water spenders have a vigorous and deep rooting system with rapid root growth and a thicker root system. Such genotypes are early and have highly effective water use, moderate transpiration and fast leaf area and canopy biomass development, moderate sink strength and superior photosynthate remobilization to pod and grain formation

    Image-based atmosphere correction using dark pixel subtraction technique in Penang Island, Malaysia / Wan Noni Afida Ab Manan, Arnis Asmat and Noordin Ahmad

    Get PDF
    Lack of study has found in emphasizing the appropriate chosen of atmospheric models with specific atmospheric condition. This study is attempting to answer whether selection of atmospheric models is based on regional atmospheric condition or geographic location. The proposed method is a combination of the radiative transfer equation and dark target subtraction technique. Two important atmospheric parameters in the radiative transfer equation which are visibility and aerosol loading are estimated from the image itself to be as an input in atmospheric modelling. ATCOR-2 was used to perform different atmospheric models (maritime and urban) which can represent regional climatic condition in Penang Island, Malaysia. By relating the determined aerosol optical thickness with visibility values, urban model at the visible (blue band) on image 2005 showed a high correlation coefficient which is r2 = 0.8896. It has been shown that determined the aerosol is highly correlated to the visibility range from 10 to 50 km. Study also found that optical satellite remotely sensed image data (Landsat TM blue band) can be used to determine the visibility value through the darkest pixel atmospheric correction algorithms

    Validation of the Enterococci indicator for bacteriological quality monitoring of beaches in Malaysia using a multivariate approach

    Get PDF
    There is currently no established bacteriological beach quality monitoring (BQM) program in place in Malaysia. To initiate cost-effective, sustainable bacteriological BQM schemes for the ultimate goal of protecting public health, policy decision makers need to be provided robust, indigenous empirical findings that validate appropriate water quality parameters for inclusion in such monitoring programs. This is the first study that assesses the validity of enterococci as an ideal indicator for bacteriological BQM in Malaysia using a multivariate approach. Beach water and sand samples from 7 beach locations were analyzed for a total of twenty-one microbial and non-microbial water quality parameters. A multivariate approach incorporating cluster analyses (CA), principal component analyses (PCA), and factor analysis (FA) was also adopted. Apart from the weak correlations of Staphylococcus aureus with concentrations of Vibro species (r = 0.302, p = 0.037) and total coliforms (r = 0.392, p = 0.006) in seawater, no correlation existed between S. aureus concentration and other parameters. Faecal coliforms failed to correlate with any of the tested parameters. Enterococci also correlated with more quality parameters than faecal coliforms or any other indicator. Multiple linear regressions highlighted a significant, best fit model that could predict enterococci concentrations in relation to other parameters with a maximum predictive success of 69.64%. PCA/FA clearly delineated enterococci and faecal coliforms as parameters that weighed strongly for BQM while Staphylococcus aureus, faecal coliforms and enterococci weighed strongly for beach sand quality monitoring. On the whole, higher correlations of enterococci levels with other parameters than was observed for faecal coliforms suggest that the former be considered a preferred parameter of choice for BQM in Malaysia. Our findings provide meaningful evidence particularly as it relates to the correlation of Enterococci with pathogens and other non-microbial parameters. It also provides empirical data to validate the applicability of the enterococci indicator paradigm for bacteriological beach quality monitoring in Malaysia. The current study thus provides policy decision makers evidenced based approach to parameter streamlining for optimized beach sampling and sustainable bacteriological quality monitoring

    Marine streptomyces SP. UKMCC_PT15 producing undecylprodigiosin with algicidal activity

    Get PDF
    Marine actinomycetes are now in demand as they are capable of producing unique and novel compounds with wide biological activities. Marine Streptomyces sp. UKMCC_PT15 previously isolated from seawater collected in Pulau Tinggi, Johor was used in this study. Molecular identification showed high similarity of Streptomyces sp. UKMCC_PT15 with Streptomyces fradiae and S. diastaticus subsp. ardesiacus based on partial sequence of 16S rRNA gene. Further characterisations of this bacterium include spore morphology using SEM, growth on various media, salt tolerance test and carbon utilisation profile. This bacterium had straight spore chain with smooth-surfaced spores and was able to tolerate up to 11% NaCl with capabilities of utilising >40 carbon sources. Undecylprodigiosin (C25H35N3O) was successfully purified through succession of column chromatography and finally using HPLC. Structure elucidation was confirmed through NMR spectroscopy, MS and comparison with established data. This compound demonstrated strong antibacterial activities against S. aureus, B. subtilis and C. albicans but weak antibacterial activities against E. coli, P. aeruginosa and Methicillin-resistant S. aureus (MRSA), Interestingly, undecylprodigiosin also demonstrated algicidal activity when tested against toxic dinoflagellates, A. minutum and P. bahamense, both of which are responsible for harmful algal blooms (HABs). Undecylprodiogiosin with concentration of 10-100 μg/ml gave ~100% algicidal activity against both dinoflagellates. Further testing with undecylprodigiosin concentration < 10 µg/ml showed that undecylprodigision was capable of killing significantly high numbers of both dinoflagellates, giving a high algicidal activity. Findings from this study suggested the potential use of undecylprodigiosin as algicidal agent which could be used for the mitigation of HABs

    Climate Smart Interventions of Small-Holder Farming Systems

    Get PDF
    Agriculture is very vulnerable to temperature and drought in semi-arid and arid regions. Farming communities are especially vulnerable to the potential impact of climate change on crop and livestock. For Pakistan, a potential increase of 2.8°C for the maximum day temperature and 2.2°C decrease in night temperature by the mid-century has been reported. The goal of this chapter is to introduce climate-smart interventions as mitigation and adaptation strategies coupled with crop diversification through the introduction of climate resilient crops in existing cropping systems. Firstly, it describes the impacts of climate change in context to current food security situation in Pakistan and, secondly, potential climate smart interventions to combat changes in the country. Crop models, their application for developing adaptations, modeling technique and its integration with breeding, remote sensing and its application, policy interventions and resource smart interventions in context to changing climate are imperative means to favor the farming community in future farming. Introducing climate resilient crops can be rescued and recognized in dry and hot areas of Pakistan using climate smart interventions and resource use efficiency may be determined with the aid of computer and decision support IT tools in resource inefficient areas

    Climate Change Impacts and Adaptation Strategies for Agronomic Crops

    Get PDF
    Climate change is a serious threat to agriculture and food security. Extreme weather conditions and changing patterns of precipitation lead to a decrease in the crop productivity. High temperatures and uncertain rainfall decrease the grain yield of crops by reducing the length of growing period. Future projections show that temperature would be increased by 2.5°C up to 2050. The projected rise in temperature would cause the high frequent and prolong heat waves that can decline the crop production. The rise in temperature results in huge reduction in yield of agronomic crops. Sustaining the crop production under changing climate is a key challenge. Therefore, adaptation measures are required to reduce the climate vulnerabilities. The adverse effect of climate change can be mitigated by developing heat tolerant cultivars and some modification in current production technologies. The development of adaptation strategies in context of changing climate provides the useful information for the stakeholders such as researchers, academia, and farmers in mitigating the negative effects of climate change

    Penentuan Cepat Toksisitas Logam Perak Menggunakan Bioluminesen Bakteri Laut Aliivibrio fischeri, Beijerinck, 1889 (Gammaproteobacteria: Vibrionaceae)

    Get PDF
    Rapid determination of toxicity based on changes in the bioluminescent signal of marine bacterium Aliivibrio fischeri (A. fischeri) to evaluate toxicity of Ag(I) has been successfully developed. Assessment of toxicity was designed using inhibition of bioluminescent signal from A. fischeri bacteria, which was exposed with toxic material of Ag(I). This metal ion was utilized as a model of toxic material to evaluate the effects of cytotoxicity on bacteria cell. Measurement of bioluminescent were taken based on differences in bacterial cell signals before and after exposure to Ag(I) ion at an emission wavelength of 488±2 nm. The concentration of bacterial cell was used to assess the toxicity of Ag(I) at optical density (OD600 nm) of 0.78 Abs. The results found that the linear response of Ag toxicity was in the range of 0.05–10 mg/L, with EC50% of 8.42 mg/L for 4 minutes. The repeatability value within the relative standard deviation (RSD) was 2.5-4.7% (n=8).  The results demonstrated that the marine bacteria of A. fischeri have good potential to evaluate toxicity of toxic material in environmental samples. Penentuan cepat toksisitas berdasarkan perubahan sinyal bioluminesen bakteri laut Aliivibrio fischeri (A. fischeri) untuk mengevaluasi toksisitas logam perak (Ag(I)) telah sukses dikembangkan. Penilaian toksisitas didesain berdasarkan penghambatan sinyal bioluminesen bakteri A. fischeri oleh bahan toksik. Ion logam Ag(I) digunakan sebagai model bahan toksik untuk menilai efek sitotiksisitas pada sel bakteri. Pengukuran bioluminesen diambil berdasarkan perbedaan sinyal sel bakteri sebelum dan sesudah diekspos pada ion logam Ag(I) pada panjang gelombang emisi 488±2 nm. Konsentrasi sel bakteri yang digunakan untuk menilai toksisitas Ag(I) pada optikal densitas 600 (OD 600 nm) = 0.78 Abs.  Hasil kajian ditemukan bahwa respons linear toksisitas Ag(I) pada rentang 0.05–10 mg/L, dengan nilai EC50% sebesar 8.42 mg/L pada waktu respons 4 menit dan nilai repeatibilitas toksisitas diperoleh sebesar 2.5-4.7 % RSD (relatif standar deviasi, n=8). Hasil ini menunjukkan bahwa bakteri laut A. fischeri memiliki potensi yang baik untuk menilai toksisitas bahan toksik dalam sampel lingkungan
    corecore