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1.
Int. microbiol ; 22(1): 49-58, mar. 2019. ilus, graf
Artigo em Inglês | IBECS | ID: ibc-184813

RESUMO

Green route for silver nanoparticle synthesis has gained increasing attention. Cyanobacteria are one of the promising organisms to produce a number of secondary metabolites that are capable of reducing silver ions to small-sized silver nanoparticles. In the present study, we employed an aqueous extract of the cyanobacterium Haloleptolyngbya alcalis KR2005/106 isolated from a soda lake for biosynthesis of silver nanoparticles (AgNPs). The extract acted as a reducing agent for AgNPs synthesis and resulted formation of nanoparticles <50 nm in size. In this study, synthesis of AgNPs obtained only in the sample exposed to photosynthetically active radiation (PAR) while the synthesis of AgNPs was not observed in the samples kept in dark. The biogenic fabrication of AgNPs was carried out by optimizing several governing parameters such as concentration of the silver nitrate solution, pH, temperature, and amount of biomass. Results obtained through different analytical techniques revealed that cyanobacterial taxon H. alcalis isolated from saline-alkaline habitat is a potential candidate for biosynthesis of optimum-sized spherical AgNPs. Surface plasmon resonance (SPR) property of AgNPs was exploited for aqueous ammonia sensing and revealed that AgNPs synthesized using aqueous extract of cyanobacterium H. alcalis could be employed for colorimetric detection of dissolved ammonia for monitoring quality of water


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Assuntos
Amônia/análise , Misturas Complexas/metabolismo , Cianobactérias/metabolismo , Nanopartículas Metálicas , Prata/metabolismo , Nitrato de Prata/metabolismo , Cianobactérias/isolamento & purificação , Escuridão , Lagos/microbiologia , Luz , Oxirredução , Ressonância de Plasmônio de Superfície
2.
Int Microbiol ; 22(1): 49-58, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30810931

RESUMO

Green route for silver nanoparticle synthesis has gained increasing attention. Cyanobacteria are one of the promising organisms to produce a number of secondary metabolites that are capable of reducing silver ions to small-sized silver nanoparticles. In the present study, we employed an aqueous extract of the cyanobacterium Haloleptolyngbya alcalis KR2005/106 isolated from a soda lake for biosynthesis of silver nanoparticles (AgNPs). The extract acted as a reducing agent for AgNPs synthesis and resulted formation of nanoparticles < 50 nm in size. In this study, synthesis of AgNPs obtained only in the sample exposed to photosynthetically active radiation (PAR) while the synthesis of AgNPs was not observed in the samples kept in dark. The biogenic fabrication of AgNPs was carried out by optimizing several governing parameters such as concentration of the silver nitrate solution, pH, temperature, and amount of biomass. Results obtained through different analytical techniques revealed that cyanobacterial taxon H. alcalis isolated from saline-alkaline habitat is a potential candidate for biosynthesis of optimum-sized spherical AgNPs. Surface plasmon resonance (SPR) property of AgNPs was exploited for aqueous ammonia sensing and revealed that AgNPs synthesized using aqueous extract of cyanobacterium H. alcalis could be employed for colorimetric detection of dissolved ammonia for monitoring quality of water.


Assuntos
Amônia/análise , Misturas Complexas/metabolismo , Cianobactérias/metabolismo , Nanopartículas Metálicas , Prata/metabolismo , Colorimetria/métodos , Cianobactérias/isolamento & purificação , Escuridão , Lagos/microbiologia , Luz , Oxirredução , Nitrato de Prata/metabolismo , Ressonância de Plasmônio de Superfície
3.
Microorganisms ; 7(2)2019 Jan 26.
Artigo em Inglês | MEDLINE | ID: mdl-30691094

RESUMO

Microorganisms thrive in extreme environments and are known for synthesizing valuable metabolites. Salt-loving microorganisms can flourish in saline environments which inhibit the growth of other microbial life, and they possess the potential to produce stable and novel biomolecules for the use in biotechnological applications, including anticancer compounds. Sambhar Lake is the largest inland soda lake in India and is an appropriate habitat for halophilic bacterial and archaeal strains in terms of diversity and potential production of bioactive compounds. In the present study, a moderately halo-alkaliphilic bacterial strain C12A1 was isolated from Sambhar Lake, located in Rajasthan, India. C12A1 was gram-positive, motile, rod-shaped, formed oval endospores, produced carotenoids, and exhibited optimal growth at 37 °C in 10⁻15% NaCl (pH 8). C12A1 was found to be able to hydrolyze skimmed milk, gelatin, and Tween 80 but unable to hydrolyze starch and carboxymethylcellulose. C12A1 showed 98.87% and 98.50% identity in 16S rRNA gene sequence to P. halophilus and P. salipiscarius, respectively. Nevertheless, C12A1 was clustered within the clade consisting of P. salipiscarius strains, but it showed a distinct lineage. Thus, C12A1 was designated as Piscibacillus sp. Cell proliferation assay results showed that C12A1 broth extract (BEP) decreased cell viability in breast cancer MDA-MB-231 cells, which was confirmed by the MTT (3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide) assay. Induction of cell toxicity was visualized by microscopy. Reverse Transcriptase PCR (RT-PCR) analysis demonstrated that BEP inhibited the expression of proliferative B-cell lymphoma-extra large (Bcl-xL) and cell cycle marker Cyclin-dependent kinase 2 (CDK2) at transcript levels. Similarly, cell migration and colony formation along with mesenchymal marker vimentin and stem cell marker BMI transcripts were found to be inhibited when cells were treated with the BEP. The anti-breast cancer potential of C12A1 indicates that microorganisms inhabiting saline-alkaline habitats, with Piscibacillus sp. in particular, are a promising source for discovery of novel bioactive substances.

4.
Toxins (Basel) ; 6(10): 2912-31, 2014 Sep 29.
Artigo em Inglês | MEDLINE | ID: mdl-25268981

RESUMO

Massive developments of potentially toxic cyanobacteria in Lake Stechlin, an oligo-mesotrophic lake in the Baltic Lake District of Germany raised concerns about toxic contamination of these important ecosystems. Field samples in the phase of mass developments of cyanobacteria were used for genetic and toxicological analyses. Microcystins and microcystin genes were detected in field samples of the lake for the first time. However, the toxins were not produced by the dominant taxa (Dolichospermum circinale and Aphanizomenon flos-aquae) but by taxa, which were present only in low biomass in the samples (Microcystis cf. aeruginosa and Planktothrix rubescens). The phytoplankton successions during the study period revealed an increase of cyanobacterial populations. The findings contribute to the changes that have been investigated in Lake Stechlin since the mid-1990s. The possible reasons behind these developments may be climate change, special weather conditions and an increased nutrient pool.


Assuntos
Toxinas Bacterianas/isolamento & purificação , Cianobactérias/genética , Genes Bacterianos , Lagos/microbiologia , Toxinas Marinhas/isolamento & purificação , Microcistinas/isolamento & purificação , Biomassa , Cianobactérias/classificação , DNA Bacteriano/genética , Alemanha , Microcystis/classificação , Microcystis/genética , Análise de Sequência de DNA , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz
5.
FEMS Microbiol Ecol ; 85(2): 389-401, 2013 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-23586739

RESUMO

Hot springs and saline-alkaline lakes of East Africa are extreme habitats regarding temperature, or salinity and pH, respectively. This study examines whether divergent habitats of Lake Bogoria, Kenya, impacts cyanobacterial community structure. Samples from the hot springs, pelagic zone and sediment were analysed by light microscopy, multilocus 454-amplicons sequencing and metagenomics to compare the cyanobacterial diversity. Most of the phylogenetic lineages of Cyanobacteria occurred exclusively in the Bogoria hot springs suggesting a high degree of endemism. The prevalent phylotypes were mainly members of the Oscillatoriales (Leptolyngbya, Spirulina, Oscillatoria-like and Planktothricoides). The Chroococcales were represented by different clades of Synechococcus but not a single phylotype clustered with any of the lineages described earlier from different continents. In contrast, we found that the pelagic zone and the sediments were inhabited by only a few taxa, dominated by Arthrospira and Anabaenopsis. Arthrospira, the main food base of Lesser Flamingo, was detected in all three habitats by amplicons pyrosequencing, indicating its resilience and key role as a primary producer. Despite the close connection between the three habitats studied, the cyanobacterial communities in the hot springs and lake differed considerably, suggesting that they are unable to adapt to the extreme conditions of the neighbouring habitat.


Assuntos
Cianobactérias/classificação , Fontes Termais/microbiologia , Lagos/microbiologia , Bactérias/genética , Biodiversidade , Cianobactérias/genética , Cianobactérias/isolamento & purificação , Ecossistema , Sedimentos Geológicos/microbiologia , Quênia , Metagenômica , Filogenia , RNA Ribossômico 16S/genética , Synechococcus/classificação , Synechococcus/genética , Clima Tropical
6.
FEMS Microbiol Ecol ; 68(3): 340-50, 2009 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-19416349

RESUMO

PCR-based denaturing gradient gel electrophoresis (DGGE) analysis of 16S rRNA gene fragments was used to identify the cyanobacterial phylotypes in sediments and plankton of saline-alkaline and freshwater lakes of Kenya. The detection of the aminotransferase domain located on modules mcyE and ndaF using specific molecular markers confirmed the presence of potential toxin-producing cyanobacteria. The eight nucleotide sequences obtained from DGGE bands were placed in three divergent cyanobacterial clusters. Five nucleotide sequences were close to members of the genera Anabaenopsis and Umezakia (Nostocales), two sequences fell in the cluster with Arthrospira sp. (Oscillatoriales) and one sequence was related to Chroococcidiopsis sp. (Pleurocapsales). The presence of the latter taxon was demonstrated de novo in the investigated lakes. All nine attained nucleotide sequences of the aminotransferase region belonged to the mcyE module. Five sequences of the aminotransferase domain were included in the cluster having the nucleotide sequence of Anabaena sp. but showed a separate lineage. Other four aminotransferases were placed in the cluster represented by nucleotide sequence of Microcystis aeruginosa. To our knowledge, this is the first report on molecular detection of cyanobacterial phylotypes in sediments of African lakes and aminotransferase domains for cyanotoxin production from sediment samples in general.


Assuntos
Toxinas Bacterianas/genética , Cianobactérias/genética , Sedimentos Geológicos/microbiologia , Toxinas Marinhas/genética , Microcistinas/genética , Microbiologia da Água , Cianobactérias/classificação , Cianobactérias/isolamento & purificação , DNA Bacteriano/genética , Eletroforese em Gel de Poliacrilamida , Água Doce/microbiologia , Quênia , Filogenia , RNA Ribossômico 16S/genética , Alinhamento de Sequência , Análise de Sequência de DNA , Transaminases/genética
7.
Microb Ecol ; 55(4): 608-18, 2008 May.
Artigo em Inglês | MEDLINE | ID: mdl-17704858

RESUMO

Anabaenopsis spp. are heterocytous cyanobacteria commonly found in tropical, subtropical, and temperate water bodies. So far, the knowledge about the phylogeny of this genus is poor. Therefore, we have isolated 15 Anabaenopsis spp. strains from Kenyan and Mexican alkaline and saline water bodies and from a Ugandan freshwater body and studied the morphology and phylogeny in a polyphasic approach. Morphologically, the investigated strains could be discriminated in two groups. One group was containing six Anabaenopsis abijatae and A. cf. abijatae strains with up to more than 500 vegetative cells in one filament, mostly single intercalary heterocyte formation, and the ability to branch out. The other group comprised nine strains of Anabaenopsis elenkinii with short filaments with up to 38 vegetative cells, intercalary heterocytes in pairs, and no ability to branch out. The morphological differences were reflected in the two distinct clusters, which were found in the phylogenetic trees of 16S rDNA and PC-IGS. While the high 16S rDNA similarity values > 97.5% found between all investigated A. abijatae and A. elenkinii strains support the assignment of these two species to one single genus, the morphological differences and the low similarity values (< 87.3) found in PC-IGS sequences between the two clusters indicate two separate genera. A close morphological and phylogenetic relationship was found for A. abijatae and Anabaenopsis (Cyanospira) rippkae.


Assuntos
Cianobactérias/classificação , Filogenia , Microbiologia da Água , Cianobactérias/citologia , Cianobactérias/genética , DNA Bacteriano/genética , DNA Espaçador Ribossômico/genética , Genes Bacterianos , Genes de RNAr , RNA Ribossômico 16S/genética , Clima Tropical
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