A. N. M. Fakhruddin

Recent advances in the development of biosensor for phenol: a review

Phenol and its derivatives are widespread contaminants whose sources are both natural and industrial. Phenol is massively produced and used as a starting material for synthetic polymers and fibers. Although phenolic compounds play important biochemical and physiological roles in living systems, their accumulation in the environment as a result of intensive human activity may result in drastic ecological problem. Various analytical techniques are available for the detection of phenol in environmental samples. But they need complex sample pre-treatment so as are time consuming, costly and use heavy devices. On the other hand a biosensor is a device that gives rapid detection, cost effective and easy. A review study was carried out to accumulate the possible biosensors for the detection of phenolic compounds in environmental samples. A number of biological components including microorganisms, enzymes, antibodies, antigens, nucleic acids etc. can be used for the construction of biosensors that was found to detect phenolic compounds. Of all type of biological components microorganisms and enzymes are mostly used. The microorganisms are Pseudomonas, Moraxella, Arthrobacter, Rhodococcus, and Trichosporon. The most used enzymes are tyrosinase, peroxidase, laccase, glucose dehydrogenase, cellobiose dehydrogenase etc. Antibody sensors can detect a very trace level. The biorecognition of DNA biosensors occur by hybridization of DNA. Biosensors are found to work well when the biological sensing element is immobilized. A variety of immobilization techniques were found to use as adsorption, covalent binding, entrapment, cross-linking etc. For immobilization the matrices used was polyvinyl alcohol, Osmium complex, nafion/sol–gel silicate, chitosan, silica gel etc.

Impacts of shrimp farming on the coastal environment of Bangladesh and approach for management

The frozen food export sector, next to readymade garments sector, is the second largest export earner of Bangladesh. Shrimp, main item of frozen food, is a major contributor in the national economy of Bangladesh since mid 1980s. Although it provides millions of employment and earns more than US

Reduction of Turbidity of Water Using Locally Available Natural Coagulants

445 million annually, it has been facing a host of challenges. Shrimp farming has been associated with a number of negative environmental and social impacts which hinder the sustainable development of this blooming sector. This paper aim to focus on how the shrimp culture in Bangladesh is affecting the adjacent environment as well as society and management approach for it’s sustain ability by means of reviewing the available scientific literatures. It finds the grave socioeconomic impacts including traditional livelihood displacement, loss of land security, food insecurity, marginalization, rural unemployment, social unrest and conflicts in the wake of shrimp culture development in Bangladesh. Similarly, environmental impacts such as mangrove degradation, loss of biodiversity, sedimentation, saltwater intrusion, and pollution and disease outbreaks are found to be the main obstacles for the development of sustainable shrimp farming. Inappropriate management practices and inadequate plans regarding water quality, seed supply, irrigation facilities and fishery resources are the main reasons for these impacts of shrimp farming. The effective management measures to mitigate the adverse environmental impact of shrimp farming development have now become urgent requirement.

Degradation of Phenol by Mixed Culture of Locally Isolated Pseudomonas Species

Turbidity imparts a great problem in water treatment. Moringa oleifera, Cicer arietinum, and Dolichos lablab were used as locally available natural coagulants in this study to reduce turbidity of synthetic water. The tests were carried out, using artificial turbid water with conventional jar test apparatus. Optimum mixing intensity and duration were determined. After dosing water-soluble extracts of Moringa oleifera, Cicer arietinum, and Dolichos lablab reduced turbidity to 5.9, 3.9, and 11.1 nephelometric turbidity unit (NTU), respectively, from 100 NTU and 5, 3.3, and 9.5, NTU, respectively, after dosing and filtration. Natural coagulants worked better with high, turbid, water compare to medium, or low, turbid, water. Highest turbidity reduction efficiency (95.89%) was found with Cicer arietinum. About 89 to 96% total coliform reduction were also found with natural coagulant treatment of turbid water. Using locally available natural coagulants, suitable, easier, and environment friendly options for water treatment were observed.

Measurement of the Growth of a Floc Forming Bacterium Pseudomonas putida CP1

Textile, pharmaceuticals and automobile waste most often contain phenolic wastes. An attempt was made to degrade phenol using locally isolated bacteria. Moreover, as in nature pure culture is rarely found rather than mixed culture, therefore, attempt was also made to improve the degradation using mixed culture of Pseudomonas species. All isolates could completely degrade phenol up to 600 ppm. Isolate Pseudomonas FA degraded 800 ppm phenol completely in 72 hours, but the isolates Pseudomonas SA, TK and KA degraded only 39.33, 43.83 and 33.16% of 800 ppm phenol respectively in 96 hours. Complete removal time was also shorter for the isolate Pseudomonas FA compares to the other isolates. Patterns of growth were similar for all of the isolates, but maximum growth was found with the isolate FA on 600 ppm phenol. Complete degradation time was decreased with mixed culture and removal rate of phenol was 25 ppm/h in mixed culture of all combinations and was higher than that of the single culture of the isolates. In mixed culture study, the growth of bacteria was also increased.

Spatial distribution and source identification of heavy metal pollution in roadside surface soil: a study of Dhaka Aricha highway, Bangladesh

Pseudomonas putida CP1 formed clumps of cells when grown on mono-chlorophenols but not on phenol or glucose. An increase in cell numbers for the organism grown on mono-chlorophenols was accompanied by a decrease in the dry weight. The change in shape of the bacterium from rod shape to coccus shape coupled with a reduction in cell size when the organism was grown under nutritional stress was found. This result together with cell aggregation affected the measurement of growth parameters in the system by conventional methods (optical density measurements, dry weight measurements and the plate count technique). Monitoring growth of Pseudomonas putida CP1 by a direct microscopic count technique was found to be more representative than conventional methods including optical density measurements, dry weight measurements and the plate count technique when grown on phenolics.

Antimicrobial Resistance of Pathogenic Bacteria Isolated from Tube Well Water of Costal Area of Sitakunda, Chittagong, Bangladesh

IntroductionIn this study, metal pollution and their sources in surface soils were evaluated by pollution indices and multivariate statistical techniques in association with a geographical information system (GIS).MethodsSurface soil samples were collected in dry season from different locations of Dhaka Aricha highway and analyzed by energy dispersive X-ray fluorescence (EDXRF).ResultsThirteen different metals were found in the tested samples. Pollution indices are determined by enrichment factor in an order of Zr > Sn > P > Mn > Zn > Rb > Fe > Ba > Sr > Ti > K > Ca > Al. The resulting geoaccumulation index (Igeo) value shows the following order: Sn > Zr > P > Mn > Zn > Rb > Fe > Ba > Ti > Sr > K > Ca > Al. Contamination factors (CFs) of the metals range from 1.422 to 3.979 (Fe); 0.213 to 1.089 (Al); 0.489 to 3.484 (Ca); 1.496 to 2.372 (K); 1.287 to 3.870 (Ti); 2.200 to 14.588 (Mn); 5.938 to 56.750 (Zr); 0.980 to 3.500 (Sr); 2.321 to 4.857 (Rb); 2.737 to 6.526 (Zn); 16.667 to 27.333 (Sn); 3.157 to 16.286 (P); and 0.741 to 3.328 (Ba). Pollution load index calculated from the CFs indicates that soils are strongly contaminated by Zr and Sn. Principal component analysis (PCA) of parameters exhibits three major components. R-mode cluster analysis reveals three distinct groups in both site and metal basis clustering that shows a similar pattern with the PCA.ConclusionsThese results might be helpful for future monitoring of further increase of heavy metal concentrations in surface soils along highways.

Detection of the residues of nineteen pesticides in fresh vegetable samples using gas chromatography–mass spectrometry

Groundwater is thought to be free of microbial contamination due to the natural filtering ability of the subsurface environment. The study is undertaken to investigate the presence pathogenic bacteria and their antimicrobial resistance pattern of groundwater of Sitakunda, Chittagong. In this study bacterial contamination in tube well water has been analyzed in terms of coliform, fecal coliform and vibrio. Qualitative analysis of bacteria is performed by spread plate technique and antibiotic susceptibility test is done by disk diffusion method. In bacteriological analysis total coliform, total fecal coliform, and total vibrio spp. count are ranged from 0.65⇥102 to 2.0⇥102 cfu/ml, 0.10⇥102 to 2.20⇥102cfu/ml and 0.0 to 0.55⇥102cfu/ml, respectively. All of the coliform isolates are resistant to ampicillin, all fecal coliform isolates to penicillin and sulphamethoxazole and vibrio spp. are resistance to erythromycin and azithromycine. The coliform isolates also display multidrug resistance. The resulting contamination of tube well water with pathogen and their resistivity to antibiotic is an alarming threat to public health, so tube well water of Sitakunda, Chittagong must be treated prior to drinks.