| 1. |
- Sharker, Bishal, et al.
(författare)
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Characterization of lignin and hemicellulose degrading bacteria isolated from cow rumen and forest soil : Unveiling a novel enzymatic model for rice straw deconstruction
- 2023
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 904
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Tidskriftsartikel (refereegranskat)abstract
- Application of greener pretreatment technology using robust ligninolytic bacteria for short duration to deconstruct rice straw and enhance bioethanol production is currently lacking. The objective of this study is to characterize three bacterial strains isolated from the milieux of cow rumen and forest soil and explore their capabilities of breaking down lignocellulose – an essential process in bioethanol production. Using biochemical and genomic analyses these strains were identified as Bacillus sp. HSTU-bmb18, Bacillus sp. HSTU-bmb19, and Citrobacter sp. HSTU-bmb20. Genomic analysis of the strains unveiled validated model hemicellulases, multicopper oxidases, and pectate lyases. These enzymes exhibited interactions with distinct lignocellulose substrates, further affirmed by their stability in molecular dynamic simulations. A comprehensive expression of ligninolytic pathways, including β-ketoadipate, phenyl acetate, and benzoate, was observed within the HSTU-bmb20 genome. The strains secreted approximately 75–82 U/mL of cellulase, xylase, pectinase, and lignin peroxidase. FT-IR analysis of the bacterial treated rice straw fibers revealed that the intensity of lignin-related peaks decreased, while cellulose-related peaks sharpened. The values of crystallinity index for the untreated control and the treated rice straw with either HSTU-bmb18, or HSTU-bmb19, or HSTU-bmb20 were recorded to be 34.48, 28.49, 29.36, 31.75, respectively, which are much higher than that of 13.53 noted for those treated with the bacterial consortium. The ratio of fermentable cellulose in rice straw increased by 1.25-, 1.79-, 1.93- and 2.17-fold following treatments with HSTU-bmb18, HSTU-bmb20, HSTU-bmb19, and a mixed consortium of these three strains, respectively. These aggregative results suggested a novel model for rice straw deconstruction utilizing hydrolytic enzymes of the consortium, revealing superior efficacy compared to individual strains, and advancing cost-effective, affordable, and sustainable green technology.
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| 2. |
- Ali, Nurshad, et al.
(författare)
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Association between arsenic exposure and plasma cholinesterase activity : a population based study in Bangladesh
- 2010
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Ingår i: Environmental Health. - : BioMed Central (BMC). - 1476-069X. ; 9:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: Arsenic is a potent pollutant that has caused an environmental catastrophe in certain parts of the world including Bangladesh where millions of people are presently at risk due to drinking water contaminated by arsenic. Chronic arsenic exposure has been scientifically shown as a cause for liver damage, cancers, neurological disorders and several other ailments. The relationship between plasma cholinesterase (PChE) activity and arsenic exposure has not yet been clearly documented. However, decreased PChE activity has been found in patients suffering liver dysfunction, heart attack, cancer metastasis and neurotoxicity. Therefore, in this study, we evaluated the PChE activity in individuals exposed to arsenic via drinking water in Bangladesh.Methods: A total of 141 Bangladeshi residents living in arsenic endemic areas with the mean arsenic exposure of 14.10 ± 3.27 years were selected as study subjects and split into tertile groups based on three water arsenic concentrations: low (< 129 μg/L), medium (130-264 μg/L) and high (> 265 μg/L). Study subjects were further sub-divided into two groups (≤50 μg/L and > 50 μg/L) based on the recommended upper limit of water arsenic concentration (50 μg/L) in Bangladesh. Blood samples were collected from the study subjects by venipuncture and arsenic concentrations in drinking water, hair and nail samples were measured by Inductively Coupled Plasma Mass Spectroscopy (ICP-MS). PChE activity was assayed by spectrophotometer.Results: Arsenic concentrations in hair and nails were positively correlated with the arsenic levels in drinking water. Significant decreases in PChE activity were observed with increasing concentrations of arsenic in water, hair and nails. The average levels of PChE activity in low, medium and high arsenic exposure groups were also significantly different between each group. Lower levels of PChE activity were also observed in the > 50 μg/L group compared to the ≤50 μg/L group. Moreover, PChE activity was significantly decreased in the skin (+) symptoms group compared to those without (-).Conclusions: We found a significant inverse relationship between arsenic exposure and PChE activity in a human population in Bangladesh. This research demonstrates a novel exposure-response relationship between arsenic and PChE activity which may explain one of the biological mechanisms through which arsenic exerts its neuro-and hepatotoxicity in humans.
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| 3. |
- Islam, Md Shofikul, et al.
(författare)
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Elevated concentrations of serum matrix metalloproteinase-2 and -9 and their associations with circulating markers of cardiovascular diseases in chronic arsenic-exposed individuals
- 2015
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Ingår i: Environmental Health. - : BioMed Central (BMC). - 1476-069X. ; 14:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: Cardiovascular diseases (CVDs) and cancers are the major causes of chronic arsenic exposure-related morbidity and mortality. Matrix metalloproteinase-2 (MMP-2) and −9 (MMP-9) are deeply involved in the pathogenesis of CVDs and cancers. This study has been designed to evaluate the interactions of arsenic exposure with serum MMP-2 and MMP-9 concentrations especially in relation to the circulating biomarkers of CVDs.Methods: A total of 373 human subjects, 265 from arsenic-endemic and 108 from non-endemic areas in Bangladesh were recruited for this study. Arsenic concentrations in the specimens were measured by inductively coupled plasma mass spectroscopy (ICP-MS) and serum MMPs were quantified by immunoassay kits.Results: Serum MMP-2 and MMP-9 concentrations in arsenic-endemic population were significantly (p < 0.001) higher than those in non-endemic population. Both MMPs showed significant positive interactions with drinking water (rs = 0.208, p < 0.001 for MMP-2; rs = 0.163, p <0.01 for MMP-9), hair (rs= 0.163, p < 0.01 for MMP-2; rs = 0.173, p < 0.01 for MMP-9) and nail (rs= 0.160, p < 0.01 for MMP-2; rs = 0.182, p < 0.001 for MMP-9) arsenic of the study subjects. MMP-2 concentrations were 1.02, 1.03 and 1.05 times, and MMP-9 concentrations were 1.03, 1.06 and 1.07 times greater for 1 unit increase in log-transformed water, hair and nail arsenic concentrations, respectively, after adjusting for covariates (age, sex, BMI, smoking habit and hypertension). Furthermore, both MMPs were increased dose-dependently when the study subjects were split into three (≤10, 10.1-50 and > 50 μg/L) groups based on the regulatory upper limit of water arsenic concentration set by WHO and Bangladesh Government. MMPs were also found to be significantly (p < 0.05) associated with each other. Finally, the concentrations of both MMPs were correlated with several circulating markers related to CVDs.Conclusions: This study showed the significant positive associations and dose–response relationships of arsenic exposure with serum MMP-2 and MMP-9 concentrations. This study also showed the interactions of MMP-2 and MMP-9 concentrations with the circulating markers of CVDs suggesting the MMP-2 and MMP-9 -mediated mechanism of arsenic-induced CVDs.
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| 4. |
- Paul, Sudip Kumar, et al.
(författare)
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Higher risk of hyperglycemia with greater susceptibility in females in chronic arsenic-exposed individuals in Bangladesh
- 2019
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Ingår i: Science of the Total Environment. - : Elsevier. - 0048-9697 .- 1879-1026. ; 668, s. 1004-1012
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Tidskriftsartikel (refereegranskat)abstract
- Arsenic (As) toxicity and diabetes mellitus (DM) are emerging public health concerns worldwide. Although exposure to high levels of As has been associated with DM, whether there is also an association between low and moderate As exposure and DM remains unclear. We explored the dose-dependent association between As exposure levels and hyperglycemia, with special consideration of the impact of demographic variables, in 641 subjects from rural Bangladesh. The total study participants were divided into three groups depending on their levels of exposure to As in drinking water (low, moderate and high exposure groups). Prevalence of hyperglycemia, including impaired glucose tolerance (IGT) and DM was significantly associated with the subjects’ drinking water arsenic levels. Almost all exposure metrics (As levels in the subjects’ drinking water, hair and nails) showed dose-dependent associations with the risk of hyperglycemia, IGT and DM. Among the variables considered, sex, age, and BMI were found to be associated with higher risk of hyperglycemia, IGT and DM. In sex-stratified analyses, As exposure showed a clearer pattern of dose-dependent risk for hyperglycemia in females than males. Finally, drinking water containing low-to-moderate levels of As (50.01–150 μg/L) was found to confer a greater risk of hyperglycemia than safe drinking water (As ≤10 μg/L). Thus the results suggested that As exposure was dose-dependently associated with hyperglycemia, especially in females. © 2019 Elsevier B.V.
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| 5. |
- Rahman, Md Aminur, et al.
(författare)
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Arsenic
- 2023
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Ingår i: Inorganic Contaminants and Radionuclides. - : Elsevier. ; , s. 13-40
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Arsenic (As) is a poisonous metalloid and recognized as a Group I human carcinogen by the International Agency for Research on Cancer (IARC). Arsenic often exists in groundwater and surface water, oceanic and inland deposits, rocks, soils, and biota at variable concentrations. Over the last few decades, As contamination has been augmented noticeably due to both natural and anthropogenic sources. Arsenic contamination in groundwater is currently a major global environmental catastrophe, which affects over 200 million people in 107 countries and causes various health complications including cancer. Therefore, updated information regarding the sources, chemical form, bioavailability, extent and severity, food safety and regulation, remediation, and management of As is essential. In this chapter, we accumulated the detailed sources of As, including point and diffuse sources, various inorganic and organic As species, and their toxicity in the environment. Moreover, the fate of As in the environment, economic implications of As-contaminated food and food products, and the bioavailability and bio-accessibility of As in environmental media are also briefly summarized. Remediation technologies for As-contaminated soil with the latest case study and regulatory limits of As in soil are also presented in this chapter. Overall, this chapter incorporates the past and contemporary knowledge of As, which will be useful for better management of As in the near future.
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