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Bioremediation of Toxic Metals for Protecting Human Health and the Ecosystem
University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre. Örebro University. (Bioteknik, Biotechnology)ORCID iD: 0000-0002-8162-8945
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Heavy metal pollutants, discharged into the ecosystem as waste by anthropogenic activities, contaminate drinking water for millions of people and animals in many regions of the world. Long term exposure to these metals, leads to several lethal diseases like cancer, keratosis, gangrene, diabetes, cardio- vascular disorders, etc. Therefore, removal of these pollutants from soil, water and environment is of great importance for human welfare. One of the possible eco-friendly solutions to this problem is the use of microorganisms that can accumulate the heavy metals from the contaminated sources, hence reducing the pollutant contents to a safe level.

In this thesis an arsenic resistant bacterium Lysinibacillus sphaericus B1-CDA, a chromium resistant bacterium Enterobacter cloacae B2-DHA and a nickel resistant bacterium Lysinibacillus sp. BA2 were isolated and studied. The minimum inhibitory concentration values of these isolates are 500 mM sodium arsenate, 5.5 mM potassium chromate and 9 mM nickel chloride, respectively. The time of flight-secondary ion mass spectrometry and inductively coupled plasma-mass spectroscopy analyses revealed that after 120 h of exposure, the intracellular accumulation of arsenic in B1-CDA and chromium in B2-DHA were 5.0 mg/g dwt and 320 μg/g dwt of cell biomass, respectively. However, the arsenic and chromium contents in the liquid medium were reduced to 50% and 81%, respectively. The adsorption values of BA2 when exposed to nickel for 6 h were 238.04 mg of Ni(II) per gram of dead biomass indicating BA2 can reduce nickel content in the solution to 53.89%. Scanning electron micrograph depicted the effect of these metals on cellular morphology of the isolates. The genetic composition of B1-CDA and B2-DHA were studied in detail by sequencing of whole genomes. All genes of B1-CDA and B2-DHA predicted to be associated with resistance to heavy metals were annotated.

The findings in this study accentuate the significance of these bacteria in removing toxic metals from the contaminated sources. The genetic mechanisms of these isolates in absorbing and thus removing toxic metals could be used as vehicles to cope with metal toxicity of the contaminated effluents discharged to the nature by industries and other human activities.

Place, publisher, year, edition, pages
Örebro: Örebro University , 2016. , 80 p.
Series
, Örebro Studies in Life Science, ISSN 1653-3100 ; 15
Keyword [en]
Heavy Metals, Pollution, Accumulation, Remediation, Human Health, Bacteria, Genome Sequencing, de novo Assembly, Gene Prediction
National Category
Other Biological Topics
Identifiers
URN: urn:nbn:se:his:diva-12885ISBN: 978-91-7529-146-8OAI: oai:DiVA.org:his-12885DiVA: diva2:959323
Public defence
2016-09-22, Hus G, sal G 111, Högskolevägen, Skövde, 13:15 (English)
Opponent
Supervisors
Available from: 2016-09-07 Created: 2016-09-07 Last updated: 2016-09-08Bibliographically approved
List of papers
1. Isolation and characterization of a Lysinibacillus strain B1-CDA showing potential for bioremediation of arsenics from contaminated water
Open this publication in new window or tab >>Isolation and characterization of a Lysinibacillus strain B1-CDA showing potential for bioremediation of arsenics from contaminated water
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2014 (English)In: Journal of Environmental Science and Health. Part A: Toxic/Hazardous Substances and Environmental Engineering, ISSN 1093-4529, E-ISSN 1532-4117, Vol. 49, no 12, 1349-1360 p.Article in journal (Refereed) Published
Abstract [en]

The main objective of this study was to identify and isolate arsenic resistant bacteria that can be used for removing arsenic from thecontaminated environment. Here we report a soil borne bacterium, B1-CDA that can serve this purpose. B1-CDA was isolated fromthe soil of a cultivated land in Chuadanga district located in the southwest region of Bangladesh. The morphological, biochemicaland 16S rRNA analysis suggested that the isolate belongs to Lysinibacillus sphaericus. The minimum inhibitory concentration (MIC)value of the isolate is 500 mM (As) as arsenate. TOF-SIMS and ICP-MS analysis confirmed intracellular accumulation and removalof arsenics. Arsenic accumulation in cells amounted to 5.0 mg g¡1 of the cells dry biomass and thus reduced the arsenicconcentration in the contaminated liquid medium by as much as 50%. These results indicate that B1-CDA has the potential forremediation of arsenic from the contaminated water. We believe the benefits of implementing this bacterium to efficiently reducearsenic exposure will not only help to remove one aspect of human arsenic poisoning but will also benefit livestock and native animalspecies. Therefore, the outcome of this research will be highly significant for people in the affected area and also for humanpopulations in other countries that have credible health concerns as a consequence of arsenic-contaminated water.

Place, publisher, year, edition, pages
Taylor & Francis, 2014
Keyword
Pollution, toxic metals, arsenics, bioremediation, bacteria, bioaccumulation
National Category
Natural Sciences Biological Sciences
Research subject
Natural sciences
Identifiers
urn:nbn:se:his:diva-9703 (URN)10.1080/10934529.2014.928247 (DOI)000340370000002 ()25072766 (PubMedID)2-s2.0-84905275614 (ScopusID)
Projects
Bioremediation
Funder
Sida - Swedish International Development Cooperation Agency
Available from: 2014-08-04 Created: 2014-08-04 Last updated: 2016-09-07Bibliographically approved
2. Bioremediation of hexavalent chromium (VI) by a soil borne bacterium, Enterobacter cloacae B2-DHA
Open this publication in new window or tab >>Bioremediation of hexavalent chromium (VI) by a soil borne bacterium, Enterobacter cloacae B2-DHA
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2015 (English)In: Journal of Environmental Science and Health. Part A: Toxic/Hazardous Substances and Environmental Engineering, ISSN 1093-4529, E-ISSN 1532-4117, Vol. 50, no 11, 1136-1147 p.Article in journal (Refereed) Published
Abstract [en]

Chromium and chromium containing compounds are discharged into the nature as waste from anthropogenic activities, such as industries, agriculture, forest farming, mining and metallurgy. Continued disposal of these compounds to the environment leads to development of various lethal diseases in both humans and animals. In this paper, we report a soil borne bacterium, B2-DHA that can be used as a vehicle to effectively remove chromium from the contaminated sources. B2-DHA is resistant to chromium with a MIC value of 1000 µg/mL potassium chromate. The bacterium has been identified as a Gram negative, Enterobacter cloacae based on biochemical characteristics and 16S rRNA gene analysis. TOF-SIMS and ICP-MS analyses confirmed intracellular accumulation of chromium and thus its removal from the contaminated liquid medium. Chromium accumulation in cells was 320 µg/g of cells dry biomass after 120 h exposure and thus it reduced the chromium concentration in the liquid medium by as much as 81%. Environmental scanning electron micrograph revealed the effect of metals on cellular morphology of the isolates. Altogether, our results indicate that B2-DHA has the potential to reduce chromium significantly to safe levels from the contaminated environments and suggest the potential use of this bacterium in reducing human exposure to chromium, hence avoiding poisoning.

Place, publisher, year, edition, pages
Taylor & Francis, 2015
Keyword
Bioremediation, Chromium, Enterobacter cloacae, Human Health, Tannery Effluents, Soil Borne Bacterium
National Category
Microbiology
Identifiers
urn:nbn:se:his:diva-10916 (URN)10.1080/10934529.2015.1047670 (DOI)26191988 (PubMedID)2-s2.0-84937800926 (ScopusID)
Available from: 2015-05-11 Created: 2015-05-11 Last updated: 2016-09-07Bibliographically approved
3. Biosorption of nickel by Lysinibacillus sp. BA2 native to bauxite mine
Open this publication in new window or tab >>Biosorption of nickel by Lysinibacillus sp. BA2 native to bauxite mine
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2014 (English)In: Ecotoxicology and Environmental Safety, ISSN 0147-6513, E-ISSN 1090-2414, Vol. 107, 260-268 p.Article in journal (Refereed) Published
Abstract [en]

The current scenario of environmental pollution urges the need for an effective solution for toxic heavy metal removal from industrial wastewater. Bioremediation is the most cost effective process employed by the use of microbes especially bacteria resistant to toxic metals. In this study, Lysinibacillus sp. BA2, a nickel tolerant strain isolated from bauxite mine was used for the biosorption of Ni(II). Lysinibacillus sp. BA2 biomass had isoelectric point (pI) of 3.3. The maximum negative zeta potential value (−39.45) was obtained at pH 6.0 which was highly favourable for Ni(II) biosorption. 238.04 mg of Ni(II) adsorbed on one gram of dead biomass and 196.32 mg adsorbed on one gram of live biomass. The adsorption of Ni(II) on biomass increased with time and attained saturation after 180 min with rapid biosorption in initial 30 min. The Langmuir and Freundlich isotherms could fit well for biosorption of Ni(II) by dead biomass while Langmuir isotherm provided a better fit for live biomass based on correlation coefficient values. The kinetic studies of Ni(II) removal, using dead and live biomass was well explained by second-order kinetic model. Ni(II) adsorption on live biomass was confirmed by SEM-EDX where cell aggregation and increasing irregularity of cell morphology was observed even though cells were in non-growing state. The FTIR analysis of biomass revealed the presence of carboxyl, hydroxyl and amino groups, which seem responsible for biosorption of Ni(II). The beads made using dead biomass of Lysinibacillus sp. BA2 could efficiently remove Ni(II) from effluent solutions. These microbial cells can substitute expensive methods for treating nickel contaminated industrial wastewaters.

Place, publisher, year, edition, pages
Elsevier, 2014
Keyword
Lysinibacillus sp. BA2, Heavy metals, Biosorption, Adsorption isotherm
National Category
Biological Sciences Natural Sciences
Research subject
Natural sciences
Identifiers
urn:nbn:se:his:diva-9704 (URN)10.1016/j.ecoenv.2014.06.009 (DOI)000342122000036 ()25011123 (PubMedID)2-s2.0-84903900011 (ScopusID)
Projects
Bioremediation
Funder
Sida - Swedish International Development Cooperation Agency
Available from: 2014-08-04 Created: 2014-08-04 Last updated: 2016-09-07Bibliographically approved
4. Comparative genome analysis of Lysinibacillus B1-CDA, a bacterium that accumulates arsenics
Open this publication in new window or tab >>Comparative genome analysis of Lysinibacillus B1-CDA, a bacterium that accumulates arsenics
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2015 (English)In: Genomics, ISSN 0888-7543, E-ISSN 1089-8646, Vol. 106, no 6, 384-392 p.Article in journal (Refereed) Published
Abstract [en]

Previously, we reported an arsenic resistant bacterium Lysinibacillus sphaericus B1-CDA, isolated from an arsenic contaminated lands. Here, we have investigated its genetic composition and evolutionary history by using massively parallel sequencing and comparative analysis with other known Lysinibacillus genomes. Assembly of the sequencing reads revealed a genome of ~ 4.5 Mb in size encompassing ~ 80% of the chromosomal DNA. We found that the set of ordered contigs contains abundant regions of similarity with other Lysinibacillus genomes and clearly identifiable genome rearrangements. Furthermore, all genes of B1-CDA that were predicted be involved in its resistance to arsenic and/or other heavy metals were annotated. The presence of arsenic responsive genes was verified by PCR in vitro conditions. The findings of this study highlight the significance of this bacterium in removing arsenics and other toxic metals from the contaminated sources. The genetic mechanisms of the isolate could be used to cope with arsenic toxicity.

Place, publisher, year, edition, pages
Elsevier, 2015
Keyword
Toxic metals, Bioremediation, Genome sequencing, de novo assembly
National Category
Biochemistry and Molecular Biology Bioinformatics and Systems Biology
Research subject
Natural sciences
Identifiers
urn:nbn:se:his:diva-11575 (URN)10.1016/j.ygeno.2015.09.006 (DOI)000365613100010 ()26387925 (PubMedID)2-s2.0-84948102629 (ScopusID)
Projects
Bioremediation
Funder
Sida - Swedish International Development Cooperation Agency, AKT-2010-18
Available from: 2015-10-02 Created: 2015-10-01 Last updated: 2016-09-07Bibliographically approved
5. Genome analysis of Enterobacter cloacae B2-DHA: A bacterium resistant to chromium and/or other heavy metals
Open this publication in new window or tab >>Genome analysis of Enterobacter cloacae B2-DHA: A bacterium resistant to chromium and/or other heavy metals
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(English)Manuscript (preprint) (Other academic)
National Category
Other Biological Topics
Identifiers
urn:nbn:se:his:diva-12886 (URN)
External cooperation:
Available from: 2016-08-31 Created: 2016-09-07 Last updated: 2016-09-07

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