Displaying publications 201 - 220 of 942 in total

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  1. A study of heavy metals and their fate in the composting of tannery sludge
    Haroun M, Idris A, Syed Omar SR
    Waste Manag, 2007;27(11):1541-50.
    PMID: 17113767
    Tannery waste is categorized as toxic and hazardous in Malaysia due to its high content of Cr (in excess of 500 mg/kg) and other heavy metals. Heavy metals, when in high enough concentrations, have the potential to be both phytotoxic and zootoxic. Heavy metals are found as contaminants in tannery sludge. This investigation aimed to identify the fate of chromium, cadmium, copper, lead, and zinc concentrations in tannery sludge throughout a 50-day composting cycle. The results of this study showed a general increase in the removal of Cr, Cd, Pb, and to a much smaller extent Zn and Cu, manifested by a decrease in their overall concentrations within the solid fraction of the final product (the decreases were likely the result of leaching). Furthermore, in using a sequential extraction method for sludge composting at different phases of treatment, a large proportion of the heavy metals were found to be associated to the residual fraction (70-80%) and fractions more resistant to extraction, X-NaOH, X-EDTA, X-HNO3 (12-29%). Less than 2% of the metals were bound to bioavailable fractions X-(KNO3+H2O).
    Matched MeSH terms: Bacteria/metabolism
  2. Studies on water quality and pathogenic bacteria in coastal water Langkawi, Malaysia
    Jalal KC, Faizul HN, Naim MA, John BA, Kamaruzzaman BY
    J Environ Biol, 2012 Jul;33(4):831-5.
    PMID: 23360015
    A study on physico-chemical parameters and pathogenic bacterial community was carried out at the coastal waters of Pulau Tuba island, Langkawi. The physico-chemical parameters such as temperature (27.43-28.88 degrees C), dissolved oxygen (3.79-6.49 mg l(-1)), pH (7.72-8.20), salinity (33.10-33.96 ppt), total dissolved solids (32.27-32.77 g l(-1)) and specific conductivity (49.83-51.63 mS cm(-1)) were observed. Station 3 and station 4 showed highest amount of nitrates (26.93 and 14.61 microg at N l(-1)) than station 1 (2.04 microg at N l(-1)) and station 2 (4.18 microg at N l(-1)). The highest concentration (12.4 +/- microg l(-1)) of chlorophyll a was observed in station 4 in October 2005. High phosphorus content (561 microg P l(-1)) was found in the station 2. Thirteen bacterial isolates were successfully identified using API 20E system. The highest amount of bacteria was observed at Station 4 (3400 CFU ml(-1)) and the lowest numberwas at Station 2 (890 CFU ml(-1)). Out of identified 13 Gram-negative bacterial isolates dominant species were Aeromonas hydrophila, Klebsiella oxytoca, Pseudomonas baumannii, Vibrio vulnificus, Proteus mirabilis, Providencia alcalifaciens and Serratia liquefaciens. Apart from this, oil biodegrading Pseudomonas putida were also identified. The study reveals the existing status of water quality is still conducive and the reasonably diverse with Gram-negative bacteria along the Pulau Tuba Langkawi.
    Matched MeSH terms: Gram-Negative Bacteria/isolation & purification*
  3. Implementation of the semi-aerobic landfill system (Fukuoka method) in developing countries: a Malaysia cost analysis
    Chong TL, Matsufuji Y, Hassan MN
    Waste Manag, 2005;25(7):702-11.
    PMID: 16009304
    Most of the existing solid waste landfill sites in developing countries are practicing either open dumping or controlled dumping. Proper sanitary landfill concepts are not fully implemented due to technological and financial constraints. Implementation of a fully engineered sanitary landfill is necessary and a more economically feasible landfill design is crucial, particularly for developing countries. This study was carried out by focusing on the economics from the development of a new landfill site within a natural clay area with no cost of synthetic liner up to 10 years after its closure by using the Fukuoka method semi-aerobic landfill system. The findings of the study show that for the development of a 15-ha landfill site in Malaysia with an estimated volume of 2,000,000 m(3), the capital investment required was about US 1,312,895 dollars, or about US 0.84 dollars/tonne of waste. Assuming that the lifespan of the landfill is 20 years, the total cost of operation was about US 11,132,536 dollars or US 7.15 dollars/tonne of waste. The closure cost of the landfill was estimated to be US 1,385,526 dollars or US 0.89 dollars/tonne of waste. Therefore, the total cost required to dispose of a tonne of waste at the semi-aerobic landfill was estimated to be US 8.89 dollars. By considering an average tipping fee of about US 7.89 dollars/tonne of waste in Malaysia in the first year, and an annual increase of 3% to about US 13.84 dollars in year-20, the overall system recorded a positive revenue of US 1,734,749 dollars. This is important information for the effort of privatisation of landfill sites in Malaysia, as well as in other developing countries, in order to secure efficient and effective landfill development and management.
    Matched MeSH terms: Bacteria/metabolism
  4. A Review of Gene Knockout Strategies for Microbial Cells
    Tang PW, Chua PS, Chong SK, Mohamad MS, Choon YW, Deris S, et al.
    Recent Pat Biotechnol, 2015;9(3):176-97.
    PMID: 27185502
    BACKGROUND: Predicting the effects of genetic modification is difficult due to the complexity of metabolic net- works. Various gene knockout strategies have been utilised to deactivate specific genes in order to determine the effects of these genes on the function of microbes. Deactivation of genes can lead to deletion of certain proteins and functions. Through these strategies, the associated function of a deleted gene can be identified from the metabolic networks.

    METHODS: The main aim of this paper is to review the available techniques in gene knockout strategies for microbial cells. The review is done in terms of their methodology, recent applications in microbial cells. In addition, the advantages and disadvantages of the techniques are compared and discuss and the related patents are also listed as well.

    RESULTS: Traditionally, gene knockout is done through wet lab (in vivo) techniques, which were conducted through laboratory experiments. However, these techniques are costly and time consuming. Hence, various dry lab (in silico) techniques, where are conducted using computational approaches, have been developed to surmount these problem.

    CONCLUSION: The development of numerous techniques for gene knockout in microbial cells has brought many advancements in the study of gene functions. Based on the literatures, we found that the gene knockout strategies currently used are sensibly implemented with regard to their benefits.

    Matched MeSH terms: Bacteria/genetics*
  5. Fulltext Synthesis, spectroscopic investigations (X-ray, NMR and TD-DFT), antimicrobial activity and molecular docking of 2,6-bis(hydroxy(phenyl)methyl)cyclohexanone
    Barakat A, Ghabbour HA, Al-Majid AM, Soliman SM, Ali M, Mabkhot YN, et al.
    Molecules, 2015;20(7):13240-63.
    PMID: 26197312 DOI: 10.3390/molecules200713240
    The synthesis of 2,6-bis(hydroxy(phenyl)methyl)cyclohexanone 1 is described. The molecular structure of the title compound 1 was confirmed by NMR, FT-IR, MS, CHN microanalysis, and X-ray crystallography. The molecular structure was also investigated by a set of computational studies and found to be in good agreement with the experimental data obtained from the various spectrophotometric techniques. The antimicrobial activity and molecular docking of the synthesized compound was investigated.
    Matched MeSH terms: Bacteria/growth & development*; Bacterial Proteins/chemistry*
  6. Pathogenic microbes of the oral environment
    Park AW, Yaacob HB
    J Nihon Univ Sch Dent, 1994 Mar;36(1):1-33.
    PMID: 8207501
    Matched MeSH terms: Bacteria/pathogenicity; Bacterial Adhesion
  7. Fulltext Disinfection and the control of nosocomial infection
    Lim VKE
    Med J Malaysia, 1995 Dec;50(4):289-90.
    PMID: 8668044
    Matched MeSH terms: Bacteria/isolation & purification
  8. Screening for antibacterial agents in three species of sea cucumbers from coastal areas of Sabah
    Ridzwan BH, Kaswandi MA, Azman Y, Fuad M
    Gen. Pharmacol., 1995 Nov;26(7):1539-43.
    PMID: 8690242
    1. Three species of sea cucumbers found in the Sabah coastal areas were screened for the presence of antibacterial activity using three methods of extraction. Tests were conducted in vitro using the agar absorption method. 2. Both the lipid extract and the methanol-solvent extract from Holothuria atra, Holothuria scabra and Bohadshia argus were found to show no antibacterial activity. 3. Phosphate-buffered saline (PBS) from H. atra and B. argus, however, inhibited the growth of all gram-positive and gram-negative bacteria. 4. Comparisons were also made between extracts from the outer layer of H. atra and its inner part, and it was found that the extract from the outer layer showed less bacterial growth inhibition property. 5. The bacterial growth inhibition property of the PBS extract from H. atra, however, is dependent on the extract's concentration. Bacterial growth inhibition was apparent after 48 hr incubation.
    Matched MeSH terms: Anti-Bacterial Agents/analysis*; Bacteria/drug effects*
  9. A comparative study of the in-vitro activity of cefepime and other cephalosporins
    Lim VK, Halijah MY
    Malays J Pathol, 1993 Jun;15(1):65-8.
    PMID: 8277793
    Cefepime is a new cephalosporin antibiotic which is highly active against both Gram-positive and Gram-negative organisms. The purpose of this study was to establish the in-vitro activity of cefepime and three other cephalosporins against recent clinical isolates from patients at the General Hospital Kuala Lumpur. A total of 334 strains comprising Enterobacteriaceae, non-fermentative Gram-negative bacilli and Staphylococcus aureus were tested for their sensitivity to cefepime, cefotaxime, ceftriaxone and ceftazidime. Minimum inhibitory concentrations of the antibiotics were established using an agar dilution method. With the exception of some strains of Flavobacterium meningosepticum, Xanthomonas maltophilia and other non-fermentative Gram-negative bacilli, cefepime was found to be active against a wide range of Gram-negative organisms. Cefepime was as or more active than the other cephalosporins against Acinetobacter, Enterobacteriaceae and methicillin-sensitive Staphylococcus aureus. Strains of Klebsiella and Salmonella that were resistant to the third generation cephalosporins were sensitive to cefepime. Cefepime could be a valuable alternative for the treatment of nosocomial infections due to multiply resistant organisms.
    Matched MeSH terms: Gram-Negative Bacteria/drug effects
  10. Use of pre-reduced swabs in bacteriology of chronic suppurative otitis media
    Indudharan R, Haq JA
    J Laryngol Otol, 1996 Oct;110(10):950-1.
    PMID: 8977860
    A simple, safe and effective procedure for improving the bacterial isolation in chronic suppurative otitis media (CSOM) is described. It is most useful for the isolation of aerobes as well as anaerobes from the middle ear.
    Matched MeSH terms: Bacteria, Anaerobic/isolation & purification
  11. Fulltext Bacteriology of healthy conjunctivae in Malaysians
    Singh M, Lim VKE
    Med J Malaysia, 1987 Mar;42(1):50-2.
    PMID: 3431502
    The eye harbours bacteria from the time of birth throughout life. Owing to its antibacterial properties, the normal conjunctival flora plays a significant role in the defence against superficial ocular infections. In view of its protective action as well as its probable role in causing ocular disease under certain circumstances, the study of the normal flora and its pattern of antibiotic susceptibility could provide useful information in the prevention and treatment of post-surgical infections. While several such surveys have been reported from various parts of the world, no data is available for the Malaysian population. This survey seeks to establish the pattern of bacterial flora in healthy conjunctivae of Malaysians. In addition, the bacterial flora of a nondiabetic population was compared to that of a diabetic population to see if there were any differences.
    Matched MeSH terms: Bacteria/isolation & purification
  12. Inactivation of insecticides by bacteria isolated from polluted waters where the mosquito larva bred in large number
    Hirakoso S, Kitago I, Harinasuta C
    Med J Malaya, 1968 Mar;22(3):249.
    PMID: 4386490
    Matched MeSH terms: Bacteria/metabolism*
  13. Dose-response analysis of toxic effect from palm oil mill effluent (POME) by-products on biohydrogen producing bacteria - A preliminary study on microbial density and determination of EC50
    Arisht SN, Abdul PM, Jasni J, Mohd Yasin NH, Lin SK, Wu SY, et al.
    Ecotoxicol Environ Saf, 2020 Oct 15;203:110991.
    PMID: 32888602 DOI: 10.1016/j.ecoenv.2020.110991
    The stimulant and toxicity effects of reported organic (acetic acid, propionic acid, butyric acid, formic acid, oil & grease) and inorganic (copper) by-products presented in palm oil mill effluent on anaerobic bacterial population were examined in this paper. The toxicity test had shown that acetic, propionic and butyric acids tend to stimulate the bacterial density level (survival rate more than 50%), while formic acid, copper, oil and grease were shown to have suppressed the density level (survival rate less than 50%). The highest biomass recorded was 1.66 mg/L for the concentration of acetic acid at 216 mg/L and lowest biomass concentration, 0.90 mg/L for copper at 1.40 mg/L. Biohydrogen-producing bacteria have a favourable growth rate around pH 5.5. The comparison of half maximal effective concentration (EC50) values between two test duration on the effects of organic and inorganic by-products postulate that bacteria had a higher tolerance towards volatile fatty acids. While acetic, butyric and propionic acids had exhibited higher tolerance EC50 values for bacteria, but the opposite trend was observed for formic acid, copper and oil & grease.
    Matched MeSH terms: Bacteria, Anaerobic/drug effects*
  14. Production of biogas from solid organic wastes through anaerobic digestion: a review
    Muhammad Nasir I, Mohd Ghazi TI, Omar R
    Appl Microbiol Biotechnol, 2012 Jul;95(2):321-9.
    PMID: 22622840 DOI: 10.1007/s00253-012-4152-7
    Anaerobic digestion treatments have often been used for biological stabilization of solid wastes. These treatment processes generate biogas which can be used as a renewable energy sources. Recently, anaerobic digestion of solid wastes has attracted more interest because of current environmental problems, most especially those concerned with global warming. Thus, laboratory-scale research on this area has increased significantly. In this review paper, the summary of the most recent research activities covering production of biogas from solid wastes according to its origin via various anaerobic technologies was presented.
    Matched MeSH terms: Bacteria, Anaerobic/metabolism*
  15. Characterization of the Aedes albopictus (Diptera: Culicidae) holobiome: bacterial composition across land use type and mosquito sex in Malaysia
    Lee JM, Yek SH, Wilson RF, Rahman S
    Acta Trop, 2020 Dec;212:105683.
    PMID: 32888935 DOI: 10.1016/j.actatropica.2020.105683
    Understanding the diversity and dynamics of the microbiota within the mosquito holobiome is of great importance to apprehend how the microbiota modulates various complex processes and interactions. This study examined the bacterial composition of Aedes albopictus across land use type and mosquito sex in the state of Selangor, Malaysia using 16S rRNA sequencing. The bacterial community structure in mosquitoes was found to be influenced by land use type and mosquito sex, with the environment and mosquito diet respectively identified to be the most likely sources of microbes. We found that approximately 70% of the microbiota samples were dominated by Wolbachia and removing Wolbachia from analyses revealed the relatively even composition of the remaining bacterial microbiota. Furthermore, microbial interaction network analysis highlighted the prevalence of co-exclusionary patterns in all networks regardless of land use and mosquito sex, with Wolbachia exhibiting co-exclusionary interactions with other residential bacteria such as Xanthomonas, Xenophilus and Zymobacter.
    Matched MeSH terms: Bacteria/isolation & purification*
  16. Fulltext Microbial Diversity and Community Variation in the Intestines of Layer Chickens
    Xiao SS, Mi JD, Mei L, Liang J, Feng KX, Wu YB, et al.
    Animals (Basel), 2021 Mar 16;11(3).
    PMID: 33809729 DOI: 10.3390/ani11030840
    The intestinal microbiota is increasingly recognized as an important component of host health, metabolism and immunity. Early gut colonizers are pivotal in the establishment of microbial community structures affecting the health and growth performance of chickens. White Lohmann layer is a common commercial breed. Therefore, this breed was selected to study the pattern of changes of microbiota with age. In this study, the duodenum, caecum and colorectum contents of white Lohmann layer chickens from same environment control farm were collected and analyzed using 16S rRNA sequencing to explore the spatial and temporal variations in intestinal microbiota. The results showed that the diversity of the microbial community structure in the duodenum, caecum and colorectum increased with age and tended to be stable when the layer chickens reached 50 days of age and the distinct succession patterns of the intestinal microbiota between the duodenum and large intestine (caecum and colorectum). On day 0, the diversity of microbes in the duodenum was higher than that in the caecum and colorectum, but the compositions of intestinal microbes were relatively similar, with facultative anaerobic Proteobacteria as the main microbes. However, the relative abundance of facultative anaerobic bacteria (Escherichia) gradually decreased and was replaced by anaerobic bacteria (Bacteroides and Ruminococcaceae). By day 50, the structure of intestinal microbes had gradually become stable, and Lactobacillus was the dominant bacteria in the duodenum (41.1%). The compositions of dominant microbes in the caecum and colorectum were more complex, but there were certain similarities. Bacteroides, Odoribacter and Clostridiales vadin BB60 group were dominant. The results of this study provide evidence that time and spatial factors are important factors affecting the intestinal microbiota composition. This study provides new knowledge of the intestinal microbiota colonization pattern of layer chickens in early life to improve the intestinal health of layer chickens.
    Matched MeSH terms: Bacteria; Bacteria, Anaerobic; Proteobacteria
  17. Biomimetic amphiphilic chitosan nanoparticles: Synthesis, characterization and antimicrobial activity
    Ahmad N, Wee CE, Wai LK, Zin NM, Azmi F
    Carbohydr Polym, 2021 Feb 15;254:117299.
    PMID: 33357867 DOI: 10.1016/j.carbpol.2020.117299
    Naturally derived antimicrobial peptides (AMPs) are an attractive source of new antimicrobial agents. However, clinical application of AMPs is associated with poor bioavailability and toxicity. In this study, we address these limitations by designing a new series of chitosan derivatives to mimic the amphiphilic topology of AMPs. The synthesized chitosan derivatives were found to self-assemble into nanoparticles in the aqueous environment. Among the compounds, a chitosan derivative grafted with arginine and oleic acid (CH-Arg-OA) exhibited the most potent antimicrobial activity, especially against Gram-negative bacteria. It also caused minimal cell death when tested in HEK293 and HepG2 cell lines, thus confirming the role of cationicity and lipophilicity for selective bacteria targeting. CH-Arg-OA exhibited its antimicrobial activity by disrupting bacterial membranes and causing the leakage of cytoplasmic contents. Thus, amphiphilic chitosan nanoparticles offer a great promise as a new class of AMPs mimics that is effective against Gram-negative bacteria.
    Matched MeSH terms: Bacteria; Gram-Negative Bacteria
  18. Fulltext A Review and Bibliometric Analysis on Applications of Microbial Degradation of Hydrocarbon Contaminants in Arctic Marine Environment at Metagenomic and Enzymatic Levels
    Verasoundarapandian G, Wong CY, Shaharuddin NA, Gomez-Fuentes C, Zulkharnain A, Ahmad SA
    Int J Environ Res Public Health, 2021 02 09;18(4).
    PMID: 33572432 DOI: 10.3390/ijerph18041671
    The globe is presently reliant on natural resources, fossil fuels, and crude oil to support the world's energy requirements. Human exploration for oil resources is always associated with irreversible effects. Primary sources of hydrocarbon pollution are instigated through oil exploration, extraction, and transportation in the Arctic region. To address the state of pollution, it is necessary to understand the mechanisms and processes of the bioremediation of hydrocarbons. The application of various microbial communities originated from the Arctic can provide a better interpretation on the mechanisms of specific microbes in the biodegradation process. The composition of oil and consequences of hydrocarbon pollutants to the various marine environments are also discussed in this paper. An overview of emerging trends on literature or research publications published in the last decade was compiled via bibliometric analysis in relation to the topic of interest, which is the microbial community present in the Arctic and Antarctic marine environments. This review also presents the hydrocarbon-degrading microbial community present in the Arctic, biodegradation metabolic pathways (enzymatic level), and capacity of microbial degradation from the perspective of metagenomics. The limitations are stated and recommendations are proposed for future research prospects on biodegradation of oil contaminants by microbial community at the low temperature regions of the Arctic.
    Matched MeSH terms: Bacteria/genetics
  19. Fulltext Clinical and bacteriological profile of diabetic foot infections in a tertiary care
    Goh TC, Bajuri MY, C Nadarajah S, Abdul Rashid AH, Baharuddin S, Zamri KS
    J Foot Ankle Res, 2020 Jun 16;13(1):36.
    PMID: 32546270 DOI: 10.1186/s13047-020-00406-y
    BACKGROUND: Diabetic foot infection is a worldwide health problem is commonly encountered in daily practice. This study was conducted to identify the microbiological profile and antibiotic sensitivity patterns of causative agents identified from diabetic foot infections (DFIs). In addition, the assessment included probable risk factors contributing to infection of ulcers that harbour multidrug-resistant organisms (MDROs) and their outcomes.

    METHODS: We carried out a prospective analysis based on the DFI samples collected from 2016 till 2018. Specimens were cultured with optimal techniques in addition to antibiotic susceptibility based on recommendations from The Clinical and Laboratory Standards Institute (CLSI). A total of 1040 pathogens were isolated with an average of 1.9 pathogens per lesion in 550 patients who were identified with having DFIs during this interval.

    RESULTS: A higher percentage of Gram-negative pathogens (54%) were identified as compared with Gram-positive pathogens (33%) or anaerobes (12%). A total of 85% of the patients were found to have polymicrobial infections. Pseudomonas aeruginosa (19%), Staphylococcus aureus (11%) and Bacteroides species (8%) appeared to be the predominant organisms isolated. In the management of Gram-positive bacteria, the most efficacious treatment was seen with the use of Vancomycin, while Imipenem and Amikacin proved to be effective in the treatment of Gram-negative bacteria.

    CONCLUSION: DFI's are common among Malaysians with diabetes, with a majority of cases displaying polymicrobial aetiology with multi-drug resistant isolates. The data obtained from this study will be valuable in aiding future empirical treatment guidelines in the treatment of DFIs. This study investigated the microbiology of DFIs and their resistance to antibiotics in patients with DFIs that were managed at a Tertiary Care Centre in Malaysia.

    Matched MeSH terms: Gram-Negative Bacteria/classification*; Gram-Negative Bacteria/drug effects; Gram-Negative Bacteria/isolation & purification; Gram-Positive Bacteria/classification*; Gram-Positive Bacteria/drug effects; Gram-Positive Bacteria/isolation & purification
  20. Characterization and biocompatibility evaluation of bacterial cellulose-based wound dressing hydrogel: effect of electron beam irradiation doses and concentration of acrylic acid
    Mohamad N, Buang F, Mat Lazim A, Ahmad N, Martin C, Mohd Amin MCI
    J Biomed Mater Res B Appl Biomater, 2017 Nov;105(8):2553-2564.
    PMID: 27690276 DOI: 10.1002/jbm.b.33776
    The use of bacterial cellulose (BC)-based hydrogel has been gaining attention owing to its biocompatibility and biodegradability. This study was designed to investigate the effect of radiation doses and acrylic acid (AA) composition on in vitro and in vivo biocompatibility of BC/AA as wound dressing materials. Physical properties of the hydrogel, that is, thickness, adhesiveness, rate of water vapor transmission, and swelling were measured. Moreover, the effect of these parameters on skin irritation and sensitization, blood compatibility, and cytotoxicity was studied. Increased AA content and irradiation doses increased the thickness, crosslinking density, and improved the mechanical properties of the hydrogel, but reduced its adhesiveness. The swelling capacity of the hydrogel increased significantly with a decrease in the AA composition in simulated wound fluid. The water vapor permeability of polymeric hydrogels was in the range of 2035-2666 [g/(m-2  day-1 )]. Dermal irritation and sensitization test demonstrated that the hydrogel was nonirritant and nonallergic. The BC/AA hydrogel was found to be nontoxic to primary human dermal fibroblast skin cells with viability >88% and was found to be biocompatible with blood with a low hemolytic index (0.80-1.30%). Collectively, these results indicate that these hydrogels have the potential to be used as wound dressings. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 2553-2564, 2017.
    Matched MeSH terms: Bacteria/chemistry*
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