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Screening of bacteria to produce polyhydroxyalkanoates from xylose

LOPES, Mateus Schreiner Garcez; ROCHA, Rafael Costa Santos; ZANOTTO, Sandra Patricia; GOMEZ, Jose Gregorio Cabrera; SILVA, Luiziana Ferreira da
Fonte: SPRINGER Publicador: SPRINGER
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
37.35%
Although xylose is a major constituent of lignocellulosic feedstock and the second most abundant sugar in nature, only 22% of 3,152 screened bacterial isolates showed significant growth in xylose in 24 h. Of those 684, only 24% accumulated polyhydroxyalkanoates after 72 h. A mangrove isolate, identified as Bacillus sp. MA3.3, yielded the best results in literature thus far for Gram-positive strains in experiments with glucose and xylose as the sole carbon source. When glucose or xylose were supplied, poly-3-hydroxybutyrate (PHB) contents of cell dry weight were, respectively, 62 and 64%, PHB yield 0.25 and 0.24 g g(-1) and PHB productivity (P(PHB)) 0.10 and 0.06 g l(-1) h(-1). This 40% P(PHB) difference may be related to the theoretical ATP production per 3-hydroxybutyrate (3HB) monomer calculated as 3 mol mol(-1) for xylose, less than half of the ATP/3HB produced from glucose (7 mol mol(-1)). In PHB production using sugar mixtures, all parameters were strongly reduced due to carbon catabolite repression. PHB production using Gram-positive strains is particularly interesting for medical applications because these bacteria do not produce lipopolysaccharide endotoxins which can induce immunogenic reactions. Moreover, the combination of inexpensive substrates and products of more value may lead to the economical sustainability of industrial PHB production.; Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP); Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Polyhydroxyalkanoates production by actinobacteria isolated from soil

MATIAS, Fernanda; BONATTO, Diego; PADILLA, Gabriel; RODRIGUES, Maria Filomena de Andrade; HENRIQUES, Joao Antonio Pegas
Fonte: NATL RESEARCH COUNCIL CANADA-N R C RESEARCH PRESS Publicador: NATL RESEARCH COUNCIL CANADA-N R C RESEARCH PRESS
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
27.05%
Polyhydroxyalkanoates (PHAs) are biodegradable and renewable polymers produced by a wide range of bacterial groups. New microbial bioprospection approaches have become an important way to find new PHA producers and new synthesized polymers. Over the past years, bacteria belonging to actinomycetes group have become known as PHA producers, such as Nocardia and Rhodococcus species, Kineosphaera limosa Liu et a]. 2002, and, more recently, Streptomyces species. In this paper, we disclose that there are more actinobacteria PHA producers in addition to the genera cited. Some unusual genera, such as Streptoalloteichus, and some genera frequently present in soil, such as Streptacidiphilus, have been found. Thirty-four isolates were able to accumulate poly(3-hydroxybutyrate) and a number of these have traces of poly(3-hydroxyvalerate) when cultivated on glucose or glucose and casein as carbon source. Furthermore, some strains showed traces of medium chain length PHA. Transmission electron microscopy demonstrated that the PHA accumulation occurs in hyphae and spores.; GENOTOX; GENOTOX; Fundação de Amparo à Pesquisa do Estado do Rio Grande do Sul (FAPERGS); FAPERGS; Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); FAPESP

Cassava wastewater as a substrate for the simultaneous production of rhamnolipids and polyhydroxyalkanoates by Pseudomonas aeruginosa

COSTA, Siddhartha G. V. A. O.; LEPINE, Francois; MILOT, Sylvain; DEZIEL, Eric; NITSCHKE, Marcia; CONTIERO, Jonas
Fonte: SPRINGER HEIDELBERG Publicador: SPRINGER HEIDELBERG
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
37.35%
Glycerol, cassava wastewater (CW), waste cooking oil and CW with waste frying oils were evaluated as alternative low-cost carbon substrates for the production of rhamnolipids and polyhydroxyalkanoates (PHAs) by various Pseudomonas aeruginosa strains. The polymers and surfactants produced were characterized by gas chromatography-mass spectrophotometry (MS) and by high-performance liquid chromatography-MS, and their composition was found to vary with the carbon source and the strain used in the fermentation. The best overall production of rhamnolipids and PHAs was obtained with CW with frying oil as the carbon source, with PHA production corresponding to 39% of the cell dry weight and rhamnolipid production being 660 mg l(-1). Under these conditions, the surface tension of the culture decreased to 30 mN m(-1), and the critical micelle concentration was 26.5 mg l(-1). It would appear that CW with frying oil has the highest potential as an alternative substrate, and its use may contribute to a reduction in the overall environmental impact generated by discarding such residues.; Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP); Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Estudo do metabolismo de ácidos graxos em Pseudomonas putida visando a modulação da composição monomérica de elastômero biodegradável.; Study of fatty acids metabolism in Pseudomonas putida aiming to modulate monomer composition of biodegradable elastomer.

Queiroz, Sonia Regina da Silva
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 30/04/2008 PT
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27.05%
Neste trabalho, foram desenvolvidas estratégias para modular a composição de elastômeros biodegradáveis da família dos polihidroxialcanoatos (PHA), produzidos por Pseudomonas, a partir de ácidos graxos ou óleos vegetais, para diversificar suas aplicações, sobretudo pela inserção de monômeros insaturados. A composição do PHA produzido variou com o tipo de ácido graxo fornecido e com sua proporção em misturas. Em genomas seqüenciados, detectaram-se dois genes fadH (codificador de 2,4-dienoilCoA hidratase) em P. aeruginosa e apenas um em outras Pseudomonas. Observou-se uma correlação entre o número de cópias de fadH no genoma e maior eficiência na oxidação de ácidos graxos insaturados. Mutantes afetados no metabolismo de ácidos graxos insaturados foram obtidos utilizando-se transposon, alguns destes mutantes apresentaram maior eficiência na incorporação de monômeros insaturados ao PHA. A clonagem e seqüenciamento de fragmentos de DNA interrompidos pelo transposon permitiram a identificação dos genes afetados nesses mutantes.; Different strategies were applied to modulate the composition of biodegradable elastomeric polyhydroxyalkanoates (PHA) accumulated by Pseudomonas from fatty acids and plant oils...

Identificação de genes envolvidos na síntese de polihidroxialcanoatos em Burkholderia cepacia linhagem IPT64.; Identification of genes involved in the synthesis of polyhydroxyalkanoates on Burkholderia cepacia strain IPT64.

Caulkins, Juliana Carvalho de Arruda
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 05/12/2008 PT
Relevância na Pesquisa
37.35%
Os polihidroxialcanoatos (PHAs) são poliésteres acumulados por microrganismos como material de reserva. O conhecimento das vias bioquímicas e enzimas envolvidas na biossíntese e degradação dos PHAs é uma importante ferramenta para auxiliar na produção industrial. A linhagem Burkholderia cepacia IPT64 é capaz de acumular uma blenda composta de P(3HB) e P(3H4PE) a partir de sacarose. Este trabalho está focado em duas das principais enzimas envolvidas na biossíntese de PHAs: a b-cetotiolase (phaA) e a PHA sintase (phaC). A primeira está associada à especificidade pelo substrato, e a segunda é considerada a enzima chave na síntese de PHAs. Neste trabalho a linhagem mutante phaC foi avaliada quanto à atividade enzimática de PHB sintase, que se constatou ter sido perdida. A presença de mais de uma tiolase no genoma de B. cepacia foi detectada. A inativação do gene phaABc identificado anteriormente, bloqueou totalmente a síntese de P(3HB), e não promoveu o aumento da quantidade total de polímero. Este resultado indica que a tiolase identificada é responsável direta do acúmulo de P(3HB). Outra indicação é que não há uma competição das vias de síntese dos dois polímeros P(3HB) e P(3H4PE), já que não houve alteração na quantidade de P(3H4PE) acumulado...

Construção de biblioteca metagenômica e prospecção de genes para a síntese de polihidroxalcanoatos; Metagenomic library construction for PHA synthase screening

Dimitrov, Mauricio Rocha
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 18/09/2009 PT
Relevância na Pesquisa
27.05%
Os microrganismos constituem dois terços da diversidade biológica na Terra, no entanto, muitos deles não podem ser cultivados por técnicas tradicionais. Portanto, o acesso a esta diversidade tem sido feita através da utilização de técnicas independentes de cultivo. Diante deste panorama, a metagenômica apresenta-se como uma alternativa, pois dispensa a necessidade de cultivo. Tal técnica possibilita inclusive a identificação e utilização do potencial metabólico destes organismos para o desenvolvimento de novos processos e produtos. Os polihidroxialcanoatos (PHAs) são poliésteres bacterianos, acumulados intracelularmente em forma de grânulos, cujas propriedades são similares a de alguns plásticos de origem petroquímica. O objetivo deste trabalho foi identificar e avaliar a diversidade de genes relacionados à produção de PHAs em bibliotecas metagenômicas de solo. A prospecção realizada resultou na identificação de clones contendo o gene phaC. De uma forma geral, pôde-se concluir que ainda há uma grande diversidade deste gene a ser descoberta no ambiente estudado.; Microorganisms constitute two third of the Earth's biological diversity, however, many of them cannot be cultured by standard techniques. Therefore...

Isolamento de bactéria produtoras de polihidroxialcanoatos de cadeia curta e média a partir de óleos vegetais; Isolation of bactéria producing polyhydroxyalkanoates containing short-chain-length and medium-chain-length monomers from plant oils

Matsuda, Tatiana Sayuri
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 09/12/2009 PT
Relevância na Pesquisa
27.05%
O potencial de bactérias em produzir polihidroxialcanoatos (PHA) a partir de óleo de soja foi avaliado com ênfase em Aeromonas spp. Dez isolados apresentando características de Aeromonas spp. (colônias amarelas em GSP agar e produção de P3HB-co-3HHx) e perfis ARDRA similares foram obtidos. Dois isolados produzindo PHAMCL foram também obtidos e experimentos de identificação adicionais serão necessários para confirmar se pertencem ao gênero Aeromonas. P3HB-co-3HHx contendo diferentes frações molares de 3HHx foram produzidos. Isolados produzindo P3HB-co-3HHx a partir de óleo de soja ou ácido láurico foram incapazes de produzir P3HB a partir de glicose sugerindo sua incapacidade de gerar monômeros 3HB a partir de acetil-CoA. Introdução de plasmídeo abrigando genes de biossíntese de P3HB de Ralstonia eutropha em isolados capazes de utilizar eficientemente óleo de soja como fonte de carbono permitiu a produção de P3HB, mas não PHA contendo monômeros de cadeia média, sugerindo uma transferência ineficiente de intermediários a partir da β-oxidação para PHA sintase.; The potential of polyhydroxyalknoates (PHA) production from plant oils was evaluated especially in Aeromonas spp. Ten isolates presenting features of Aeromonas spp. (yellow colonies in GSP agar and production of P3HB-co-3HHx) and similar ARDRA profiles were obtained. Two isolates producing PHAMCL were also obtained and further identification experiments will be needed to confirm their position in Aeromonas genus. P3HB-co-3HHx containing different molar fractions of 3HHx were produced. Isolates producing P3HB-co-3HHx from soybean oil or lauric acid were unable to produce P3HB from glucose suggesting their incapability to generate 3HB monomers from acetyl-CoA. Introduction of a plasmid harboring P3HB biosynthesis genes from Ralstonia eutropha into isolates able to use efficiently soybean oil as carbon source allowed the production of P3HB but not PHA containing HAMCL suggesting an inefficient transfer of intermediates from β-oxidation to PHA synthase.

Cassava wastewater as a substrate for the simultaneous production of rhamnolipids and polyhydroxyalkanoates by Pseudomonas aeruginosa

Costa, Siddhartha G. V. A. O.; Lepine, Francois; Milot, Sylvain; Deziel, Eric; Nitschke, Marcia; Contiero, Jonas
Fonte: Springer Heidelberg Publicador: Springer Heidelberg
Tipo: Artigo de Revista Científica Formato: 1063-1072
ENG
Relevância na Pesquisa
37.35%
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Glycerol, cassava wastewater (CW), waste cooking oil and CW with waste frying oils were evaluated as alternative low-cost carbon substrates for the production of rhamnolipids and polyhydroxyalkanoates (PHAs) by various Pseudomonas aeruginosa strains. The polymers and surfactants produced were characterized by gas chromatography-mass spectrophotometry (MS) and by high-performance liquid chromatography-MS, and their composition was found to vary with the carbon source and the strain used in the fermentation. The best overall production of rhamnolipids and PHAs was obtained with CW with frying oil as the carbon source, with PHA production corresponding to 39% of the cell dry weight and rhamnolipid production being 660 mg l(-1). Under these conditions, the surface tension of the culture decreased to 30 mN m(-1), and the critical micelle concentration was 26.5 mg l(-1). It would appear that CW with frying oil has the highest potential as an alternative substrate, and its use may contribute to a reduction in the overall environmental impact generated by discarding such residues.

Polyhydroxyalkanoates : waste glycerol upgrade into electrospun fibrous scaffolds for stem cells culture

Canadas, Raphael F.; Cavalheiro, João M.B.T.; Guerreiro,João D.T.; Almeida, M. Catarina M.D. de; Pollet, Eric; Silva, Cláudia Lobato da; Fonseca, M.M.R. da; Ferreira, Frederico Castelo
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em /11/2014 ENG
Relevância na Pesquisa
37.35%
This integrated study shows that waste glycerol can be bio-valorized by the fabrication of electrospun scaffolds for stem cells. Human mesenchymal stem cells (hMSC) provide an interesting model of regenerating cells because of their ability to differentiate into osteo-, chrondro-, adipo- and myogenic lineages. Moreover, hMSC have modulatory properties with potential on treatment of immunologic diseases. Electrospun fiber meshes offer tunable mechanical and physical properties that can mimic the structure of the native extracellular matrix, the natural environment where cells inhabit. Following a biorefinery approach, crude glycerol directly recovered from a biodiesel post-reaction stream was fed as major C source toCupriavidus necator DSM 545 to produce polyhydroxyalkanoates at polymer titers of 9â 25 g/L. Two of the P(3HB-4HB-3HV) terpolymers produced, one containing 11.4% 4HB and 3.5% 3HV and the other containing 35.6% 4HB and 3.4% 3HV, were electrospun into fibers of average diameters of 600 and 1400 nm, respectively. hMSC were cultured for 7 days in both fiber meshes, showing their ability to support stem cell growth at acceptable proliferation levels. Comparative results clearly demonstrate that scaffold topology is critical...

Food waste valorization through the production of polyhydroxyalkanoates by mixed microbial cultures

Carmo, Inês Miguel Troles Duarte do
Fonte: Faculdade de Ciências e Tecnologia Publicador: Faculdade de Ciências e Tecnologia
Tipo: Dissertação de Mestrado
Publicado em //2013 ENG
Relevância na Pesquisa
37.35%
Dissertação para obtenção do Grau de Mestre em Engenharia Química e Bioquímica; Polyhydroxyalkanoates (PHAs) are polyesters of hydroxyl fatty acids, which are accumulated in microbial cells as carbon/energy reserves. PHAs are bio-based and biodegradable and display a wide range of thermoplastic properties, being a promising alternative to conventional plastics. Presently, industrial PHA production was primarily based on pure microbial cultures. Although this process has high PHA production efficiency, it presents high costs associated with the use of chemically-defined feedstocks, and to the need for sterility. An attractive feature of mixed microbial cultures (MMCs) PHAs production is the ability to use waste/surplus feedstocks. Many industrial wastes are seasonally produced making it necessary find the best method of utilization of this feedstock on PHA production process. Two different approaches might be taken account: (1) stock of industrial wastes during their production for their use throughout the year. However, the high fermentability of these agro-industrial wastes makes them susceptible to degradation during storage period; (2) the use of different feedstocks over the year according its availability. It is thus important to study MMC’s response to different feedstocks. The aim of this work is study how MMC PHA production process is affected by a feedstock shift...

Investigation of the regulation mechanisms for bioplastics production from industrial residues

Pedras, Maria Inês Machado
Fonte: Faculdade de Ciências e Tecnologia Publicador: Faculdade de Ciências e Tecnologia
Tipo: Dissertação de Mestrado
Publicado em //2013 ENG
Relevância na Pesquisa
27.53%
Dissertação para obtenção do Grau de Mestre em Biotecnologia; The current high demand for plastics has become unsustainable. Polyhydroxyalkanoates are biopolymers stored by bacteria that can potentially replace modern plastics due to: wide range of applications; biodegradability; use of renewable resources as feedstock. High costs of current Polyhydroxyalkanoates production can be reduced using mixed cultures of organisms. Activated sludge from wastewater treatment plants is selected for Polyhydroxyalkanoates production through the imposition of cycles of intermittent feeding. In this study, the acclimation of activated sludge using synthetic volatile fatty acids (VFAs) as substrate resulted in a culture rich in Paracoccus spp. and unidentified filamentous bacteria. Low cost substrates such as sugarcane molasses (SM) or cheese whey (CW) can be employed as feedstock for further cost reduction. This requires an additional step before the microbial selection to ferment the feedstock into VFAs. In this work, the feedstock was changed from SM to CW. The population fed with SM was rich in Actinomycetaceae, while the population fed with CW was rich in Streptococcaceae, affecting the VFA composition. Consequently, the PHA-storing population and the polymer were affected. In the fermented SM (fSM) phase...

Constraint-based modelling of mixed microbial populations: Application to polyhydroxyalkanoates production

Pardelha, Filipa Alexandra Guerreiro
Fonte: Faculdade de Ciências e Tecnologia Publicador: Faculdade de Ciências e Tecnologia
Tipo: Tese de Doutorado
Publicado em //2013 ENG
Relevância na Pesquisa
37.35%
Dissertação para obtenção do Grau de Doutor em Engenharia Química e Bioquímica; The combined use of mixed microbial cultures (MMC) and fermented feedstock as substrate may significantly decrease polyhydroxyalkanoates (PHA) production costs and make them more competitive in relation to conventional petroleum-based polymers. However, there still exists a lack of knowledge at metabolic level that limits the development of strategies to make this process more effective. In this thesis, system biology computational tools were developed and applied to PHA production by MMC from fermented sugar cane molasses, rich in volatile fatty acids (VFA). Firstly, a metabolic network able to describe the uptake of complex mixtures of VFA and PHA production was defined. This metabolic network was applied to metabolic flux analysis (MFA) to describe substrate uptake and PHA production fluxes over the enrichment time of a culture submitted to the feast and famine regimen. Then, the minimization of the tricarboxylic acid cycle (TCA) fluxes was identified as the key metabolic objective of a MMC subjected to this regimen by flux balance analysis (FBA). This model enabled to predict, with an acceptable accuracy, the PHA fluxes and biopolymer composition. Subsequently...

Screening of polyhydroxyalkanoates producing bacteria isolated from marine ecosystems

Baptista, Silvia de Almeida
Fonte: Universidade da Beira Interior Publicador: Universidade da Beira Interior
Tipo: Dissertação de Mestrado
Publicado em //2013 ENG
Relevância na Pesquisa
37.53%
Polyhydroxyalkanoates (PHAs) are biodegradable polyesters and environmentally friendly thermoplastics, which are accumulated as carbon and energy storage materials in various bacteria in limited growth conditions with excess carbon sources. In this study, bacteria were isolated from samples taken from various marine ecosystems in the Archipelago of Madeira in the Atlantic Ocean, and screened for their ability to accumulate polyhydroxyalkanoates. These samples were taken from the seabed at depths of 30 and 1,700 meters to obtain a larger diversity of microorganisms and therefore, in an attempt to obtain new structures of PHAs. Strains were directly isolated from 612 mother plates where marine samples had been initially plated. A total of 724 isolates from mother plates were obtained, of which 174 were found PHA-positive using Nile red viable-colony screening. All synthesized intracellular inclusions during growth on starch carbon source. Twenty-five bacterial isolates in 25 mL-scale cultivation were proven promising for PHA production with PHA storage maximum 17.71 % for MD12-107 and 9.30 % for MD12-581 strain. The inclusions were predominantly identified as poly-β-hydroxybutyrate (PHB) using gas chromatography. Strains MD12-107 and MD12-581 were tested in 100 mL-scale and bioreactor cultivation. The best results were achieved with strain MD12-581 accumulated PHA storage 15.40 % in less than 6.5 hours with 5.5 g/L of cell dry weight and a specific growth rate was 0.24 h-1 when grown in medium containing 40 g/L of starch...

Cybernetic structured modeling of the production of polyhydroxyalkanoates by Alcaligenes Eutrophus

FERRAZ,L.; BONOMI,A.; PICCOLI,R. A. M.; KAPRITCHKOFF,F. M.; SCHMIDELL,W.; ALLI,R. C. P.; TAKANO,C. Y.; MATTOS,M. N.; OLIVEIRA,V.; FONTOLAN,V.
Fonte: Brazilian Society of Chemical Engineering Publicador: Brazilian Society of Chemical Engineering
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/1999 EN
Relevância na Pesquisa
37.35%
This paper presents a cybernetic structured mathematical model developed for the fermentation step of the process of production of the copolymer of polyhydroxyalkanoates by the bacteria Alcaligenes eutrophus. This process is performed in two different fermentation stages. The first emphasizes the growth of the microorganism in a batch operation without substrates limitations, while in the second, the focus is on copolymer production by a fed-batch operation in the absence of the nitrogen source. This paper presents the results of the treatment of experimental data and of preliminary parameter estimation. The fitting of the proposed model to the experimental data of a standard experiment showed a good agreement.

Production of polyhydroxyalkanoates (PHAs) by Bacillus subtilis and Escherichia coli grown on cane molasses fortified with ethanol

Gomaa,Eman Zakaria
Fonte: Instituto de Tecnologia do Paraná - Tecpar Publicador: Instituto de Tecnologia do Paraná - Tecpar
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/02/2014 EN
Relevância na Pesquisa
37.35%
The aim of this work was to study the production of polyhydroxyalkanoates (PHAs) by Bacillus subtilis and Escherichia coli isolated from the industrial contaminated soil samples using cane molasses as an inexpensive substrate. The amount of PHA accumulated followed a similar pattern to its growth for each of treatment indicating a growth-related production, yielding maximum PHA production of 54.1 and 47.16% for B. subtilis and E. coli, respectively after 96 h cultivation in the medium containing 6 and 8 % molasses, respectively and decreased thereafter. The growth and PHA yields were improved by introducing 1% ethanol into the molasses medium. Ammonium sulphate and ammonium nitrate at a concentration of 1 g/L served as the best nitrogen sources for bacterial growth, allowing B. subtilis and E. coli cells to accumulate PHA up to 62.21 and 58.7%, respectively. The optimum environmental conditions that influenced the PHA production by the two strains were inoculum concentration of 8%, pH 7.0 and a temperature of 35°C. The functional groups of the extracted PHA granules were identified by Fourier transform infrared (FTIR) spectroscopy analysis.

Effect of process variables on the production of Polyhydroxyalkanoates by activated sludge

Mokhtarani, Nader; Ganjidoust, Hossein; Vasheghani Farahani, Ebrahim
Fonte: BioMed Central Publicador: BioMed Central
Tipo: Artigo de Revista Científica
Publicado em 07/09/2012 EN
Relevância na Pesquisa
27.74%
Polyhydroxyalkanoates are known to be temporarily stored by microorganisms in activated sludge, especially in anaerobic-aerobic processes. Due to the problems resulted from the disposals of plastic wastes and excess sludge of wastewater treatment plants, the production of polyhydroxyalkanoates by treating activated sludge and determining the effect of process variables were the main issues of this paper. In this research, an anaerobic-aerobic sequencing batch reactor was used to make microorganism adapted and a batch aerobic reactor was used for enriching them. The variables affecting polyhydroxyalkanoates production including aeration time, sludge retention time, and volatile fatty acids concentration of the influent in sequencing batch reactor, and also carbon to nitrogen ratio and cultivation time in polymer production reactor, were investigated using Taguchi statistical approach to determine optimum conditions. The maximum polymer production of 29% was achieved at sludge retention time of 5–10 days, aeration time of 2 hours, supplementation of 40% of volatile fatty acids in the influent and increasing of carbon to nitrogen ratio of polymer production reactor to above 25 g/g. Based on the results, in optimum conditions, the volatile fatty acids concentration which increased the production of polyhydroxyalkanoates up to 49% was the most effective variable. Carbon to nitrogen ratio...

Isolation and Screening of Polyhydroxyalkanoates Producing Bacteria from Pulp, Paper, and Cardboard Industry Wastes

Bhuwal, Anish Kumari; Singh, Gulab; Aggarwal, Neeraj Kumar; Goyal, Varsha; Yadav, Anita
Fonte: Hindawi Publishing Corporation Publicador: Hindawi Publishing Corporation
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
27.35%
Background. Polyhydroxyalkanoates (PHAs) are storage materials that accumulate by various bacteria as energy and carbon reserve materials. They are biodegradable, environmentally friendly, and also biocompatible bioplastics. Unlike petrochemical-based plastics that take several decades to fully degrade, PHAs can be completely degraded within a year by variety of microorganisms into CO2 and water. In the present study, we aim to utilize pulp, paper, and cardboard industry sludge and waste water for the isolation and screening of polyhydroxyalkanoates (PHAs) accumulating bacteria and production of cost-effective PHB using cardboard industry waste water. Results. A total of 42 isolates showed black-blue coloration when stained with Sudan black B, a preliminary screening agent for lipophilic compounds, and a total of 15 isolates showed positive result with Nile blue A staining, a more specific dye for PHA granules. The isolates NAP11 and NAC1 showed maximum PHA production 79.27% and 77.63% with polymer concentration of 5.236 g/L and 4.042 g/L with cardboard industry waste water. Both of the selected isolates, NAP11 and NAC1, were classified up to genus level by studying their morphological and biochemical characteristics and were found to be Enterococcus sp....

The Diversity of Bacteria Isolated from Antarctic Freshwater Reservoirs Possessing the Ability to Produce Polyhydroxyalkanoates

Ciesielski, Slawomir; Górniak, Dorota; Możejko, Justyna; Świątecki, Aleksander; Grzesiak, Jakub; Zdanowski, Marek
Fonte: Springer US Publicador: Springer US
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
27.35%
The diversity of polyhydroxyalkanoates-producing bacteria in freshwater reservoirs in the Ecology Glacier foreland, Antarctica, was examined by a cultivation-dependent method. Isolated strains were analyzed phylogenetically by 16S rRNA gene sequencing, and classified as members of Alpha-, Beta-, or Gammaproteobacteria classes. Polymerase chain reaction was used to detect PHA synthase genes. Potential polyhydroxyalkanoates (PHAs) producers belonging mainly to Pseudomonas sp., and Janthinobacterium sp. were isolated from all five sampling sites, suggesting that PHA synthesis is a common bacterial feature at pioneer sites. All Pseudomonas strains had the genetic potential to synthesize medium-chain-length PHAs, whereas some isolated Janthinobacterium strains might produce short-chain-length PHAs or medium-chain-length PHAs. It is the first report revealing that Janthinobacterium species could have the potential to produce medium-chain-length PHAs.

Screening of polyhydroxyalkanoates producing bacteria isolated from marine ecosystems

Baptista, Silvia de Almeida
Fonte: Universidade da Beira Interior Publicador: Universidade da Beira Interior
Tipo: Dissertação de Mestrado
Publicado em //2013 ENG
Relevância na Pesquisa
37.53%
Polyhydroxyalkanoates (PHAs) are biodegradable polyesters and environmentally friendly thermoplastics, which are accumulated as carbon and energy storage materials in various bacteria in limited growth conditions with excess carbon sources. In this study, bacteria were isolated from samples taken from various marine ecosystems in the Archipelago of Madeira in the Atlantic Ocean, and screened for their ability to accumulate polyhydroxyalkanoates. These samples were taken from the seabed at depths of 30 and 1,700 meters to obtain a larger diversity of microorganisms and therefore, in an attempt to obtain new structures of PHAs. Strains were directly isolated from 612 mother plates where marine samples had been initially plated. A total of 724 isolates from mother plates were obtained, of which 174 were found PHA-positive using Nile red viable-colony screening. All synthesized intracellular inclusions during growth on starch carbon source. Twenty-five bacterial isolates in 25 mL-scale cultivation were proven promising for PHA production with PHA storage maximum 17.71 % for MD12-107 and 9.30 % for MD12-581 strain. The inclusions were predominantly identified as poly-β-hydroxybutyrate (PHB) using gas chromatography. Strains MD12-107 and MD12-581 were tested in 100 mL-scale and bioreactor cultivation. The best results were achieved with strain MD12-581 accumulated PHA storage 15.40 % in less than 6.5 hours with 5.5 g/L of cell dry weight and a specific growth rate was 0.24 h-1 when grown in medium containing 40 g/L of starch...

Impact of carbon/nitrogen feeding strategy on polyhydroxyalkanoates production using mixed microbial cultures

Silva, Fernando Ramos
Fonte: Universidade Nova de Lisboa Publicador: Universidade Nova de Lisboa
Tipo: Dissertação de Mestrado
Publicado em /12/2015 ENG
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Polyhydroxyalkanoates (PHA) production using mixed microbial cultures (MMC) requires a multi-stage process involving the microbial selection of PHA-storing microorganisms, typically operated in sequencing batch reactors (SBR), and an accumulation reactor. Since low-cost renewable feedstocks used as process feedstock are often nitrogen-deficient, nutrient supply in the selection stage is required to allow for microbial growth. In this context, the possibility to uncouple nitrogen supply from carbon feeding within the SBR cycle has been investigated in this study. Moreover, three different COD:N ratios (100:3.79, 100:3.03 and 100:2.43) were tested in three different runs which also allowed the study of COD:N ratio on the SBR performance. For each run, a synthetic mixture of acetic and propionic acids at an overall organic load rate of 8.5 gCOD L-1 d-1 was used as carbon feedstock, whereas ammonium sulfate was the nitrogen source in a lab-scale sequence batch reactor (SBR) with 1 L of working volume. Besides, a sludge retention time (SRT) of 1 d was used as well as a 6 h cycle length. The uncoupled feeding strategy significantly enhanced the selective pressure towards PHA-storing microorganisms, resulting in a two-fold increase in the PHA production (up to about 1.3 gCOD L-1). A high storage response was observed for the two runs with the COD:N ratios (gCOD:gN) of 100:3.79 and 100:3.03...