Human activities in a large array of industrial and agricultural sectors produce chemical contaminants which are chiefly hydrocarbons of various types that are potentially toxic and carcinogenic to aquatic and terrestrial organisms. Globally, millions of tons of these pollutants are generated annually, and in some areas, they are released indiscriminately to the environment. In order to overcome this problem, microbiological decontamination or bioremediation has been suggested. Bioremediation has been argued to be an efficient, economic, and adaptable alternative to physicochemical remediation. However, to date, such claims of successful bioremediation are often not supported by evidence from toxicity studies. In this regard, luminescent bacteria have been employed in some hydrocarbon remediation experiments to denote reduction in toxicity. In this review, the utilization of luminescence bacteria as toxicity monitoring agent for hydrocarbon remediation is discussed.
Exposure to types of asbestos such as chrysotile and crocidolite increases respiratory disease risks such as lung cancer, mesothelioma, and asbestosis. Nevertheless, asbestos products banning in Malaysia is only limited to crocidolite as per stated in OSHA (Prohibition of Use of Substance) Order 1999, though other types are highly suspected to be found in asbestos-containing materials (ACM) like brake pads and linings. This study ascertains the presence of asbestos fibres, particularly chrysotile, in brake pads and linings used in Malaysia's vehicle and heavy vehicle sector. Seven different brake pads; three from vehicle brands, and four from heavy vehicle brands were collected by bulk sampling approaches from the market and field. Dust fibres were extracted using slow grinding method and analysed under Polarized Light Microscope (PLM). The fibre characteristics such as colour, morphology, pleochroism, extinction, and dispersion staining technique were examined, referring the National Institute for Occupational Safety and Health (NIOSH) Manual of Analytical Methods (NMAM) 9002. Additionally, the observed samples also were verified by an accredited lab to support the authenticity of the outcome. From the analysis and lab results, chrysotile fibres were consistently detected in all brake pad samples, fulfilling the fibre characteristics and positive elongation signs.
Pollution in the environment is deteriorating the ecology due to human activities in a large array of industrial and agricultural sectors. Bioassay of polluted waters using bioluminescent bacterium has been touted as one of the most economical, rapid and sensitive tests. The growth of the bacterium on seawater medium exhibited a typical sigmoidal profile. To extract important growth parameters useful for further modelling exercise, various primary growth models were utilized in this study such as Modified Logistic, modified Gompertz, modified Richards, modified Schnute, Baranyi-Roberts, von Bertalanffy, Huang and the Buchanan three-phase model. The best performance was Huang model with the lowest value for RMSE, AICc and the highest value for adjusted R2. The AF and BF values were also excellent for the model with their values were the closest to 1.0. The Huang parameters, which include A or Y0 (bacterial growth lower asymptote), ïm (maximum specific bacterial growth rate), ï¬ (lag time) and Ymax (bacterial growth upper asymptote) were 7.866 (95% confidence interval of 7.850 to 7.883), 0.329 (95% confidence interval of 0.299 to 0.359), 1.543 (95% confidence interval of 1.303 to 1.784) and 8.511 (95% confidence interval of 0.299 to 0.359).
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