Beyond PHA: Stimulating intracellular accumulation of added-value compounds in mixed microbial cultures

This review compiled and analyzed the operational conditions (dissolved oxygen, feast and famine ratio, sequential batch reactor cycle length, organic loading rate (OLR), pH, C/N, and temperature) established during the feast and famine culture strategy for the mixed microbial cultures (MMC) selection to understand how these variables could affect the synthesis of polyhydroxyalkanoates, polyglucose, triacylglycerides, levulinic acid and adipic acid from non-fermented substrates. According to the reported information, the dissolved oxygen has a greater impact on the type and amount of produced compound. In a lesser extent, the OLR and the cycle length were identified to have an impact on the accumulation of polyhydroxyalkanoates, whose accumulation was favored at lower OLR and longer cycle lengths. Thereby, the information of this work will allow the design of future strategies for the simultaneous accumulation of compounds of interest other than the polyhydroxyalkanoates or understand the operational conditions that would optimize the polyhydroxyalkanoates production

Effect of cobalt supplementation and fractionation on the biological response in the biomethanization of Olive Mill Solid Waste

Due to the low trace metals concentration in the Olive Mill Solid Waste (OMSW), a proposed strategy to improve its biomethanization is the supplementation of key metals to enhance the microorganism activity. Among essential trace metals, cobalt has been reported to have a crucial role in anaerobic degradation. This study evaluates the effect of cobalt supplementation to OMSW, focusing on the connection between fractionation of cobalt in the system and the biological response. The highest biological responses was found in a range from 0.018 to 0.035 mg/L of dissolved cobalt (0.24-0.65 mg total cobalt/L), reaching improvements up to 23% and 30% in the methane production rate and the methane yield coefficient, respectively. It was found that the dissolved cobalt fraction is more accurately related with the biological response than the total cobalt. The total cobalt is distorted by the contribution of dissolved and non-dissolved inert fractions. (C) 2016 Elsevier Ltd. All rights reserved

Effect of cobalt supplementation and fractionation on the biological response in the biomethanization of Olive Mill Solid Waste

28 Páginas; 5 Figuras; 3 TablasDue to the low trace metals concentration in the Olive Mill Solid Waste (OMSW), a proposed strategy to improve its biomethanization is the supplementation of key metals to enhance the microorganism activity. Among essential trace metals, cobalt has been reported to have a crucial role in anaerobic degradation. This study evaluates the effect of cobalt supplementation to OMSW, focusing on the connection between fractionation of cobalt in the system and the biological response. The highest biological responses was found in a range from 0.018 to 0.035 mg/L of dissolved cobalt (0.24–0.65 mg total cobalt/L), reaching improvements up to 23% and 30% in the methane production rate and the methane yield coefficient, respectively. It was found that the dissolved cobalt fraction is more accurately related with the biological response than the total cobalt. The total cobalt is distorted by the contribution of dissolved and non-dissolved inert fractions.The authors are very grateful to the Spanish Ministry of Economy and Competitiveness for funding this research through Project CTM2015-55095-R. The authors would also like to thank to the Marie Curie’s International Research Staff Exchange Scheme (IRSES) “Renewable energy production through microalgae cultivation: closing material cycles” (PIRSES-GA-2011-295165) for providing financial support. David Jeison wishes to thank support provided by CRHIAM Centre (CONICYT/FONDAP/15130015).Peer reviewe

Risks of using EDTA as an agent for trace metals dosing in anaerobic digestion of olive mill solid waste

Low concentrations of trace elements in many organic wastes recommend their supplementation in order to avoid potential limitations. Different chelating agents have been used to ensure an adequate trace metal pool in the soluble fraction, by forming dissolved complexes. Ethylenediaminetetraacetic acid (EDTA) is probably the most common, although several negative effects could be associated with its usage. Biomethane potential tests were performed using Olive Mill Solid Waste as the substrate, supplementing different combinations of Fe, Co, Ni, Ba, always under the presence of EDTA. Results show that Ni and Co slightly recovered biodegradability. However, Ba supplementation resulted in worsening the methane yield coefficient in all cases. High concentration of EDTA led to decrease in the activity of anaerobic digestion. High availability of EDTA induces the capture of trace metals like Co or Ni, key trace metals for anaerobic biomass activity. While supplementing trace metals, the addition of Ba and/or EDTA must be carefully considered

Aquaculture Sludge as Co-Substrate for Sustainable Olive Mill Solid Waste Pre-Treatment by Anthracophyllum discolor

12 Páginas.-- 3 Figuras.-- 3 TablasOlive mill solid waste (OMSW) is an agro-industrial waste that has a high content of recalcitrant lignocellulose, which can adversely affect the environment. This study aimed to evaluate the phenol and lignin removal and the enzyme activity involved in the biological pre-treatment of OMSW supplemented with aquaculture sludge (AS) as an external nitrogen source by Anthracophyllum discolor. The highest lignin removal and enzymatic activity performance was obtained in the mixture of OMSW and AS prepared at a C/N ratio 45. In these conditions, the pre-treatment could remove 66% of lignin and 68% of phenols in the solid phase and 56% of phenols in the liquid phase and the maximum activity of laccase, manganese peroxidase and manganese independent peroxidase were of 10, 289 and 75 U L−1 in 25, 30, and 15 days of pre-treatment, respectively. These results propose that the addition of AS as a co-substrate for adjusting the C/N ratio allows a 41 and 141% increase in lignin removal and manganese peroxidase activity respectively, enabling the treatment of both OMSW and AS wastes and the possible recovery of an enzymatic extract of biotechnological interest.Fondecyt Project No. 1191230, Agencia Nacional de Investigación y Desarrollo de Chile, ANID.Peer reviewe

Strategy for biological co-production of levulinic acid and polyhydroxyalkanoates by using mixed microbial cultures fed with synthetic hemicellulose hydrolysate

Hemicellulose hydrolysates (HH), which could be an interesting carbon source to feed mixed microbial cultures (MMC) able to accumulate high value-added compounds. This research focused on the evaluation of a culture strategy to achieve the simultaneous biological production of Levulinic Acid (LA) and Polyhydroxyalcanoates (PHA) by MMC fed with a synthetic HH (SHH). The culture strategy involves the use of sequential batch reactors (SBR) to select microorganisms capable of producing LA and PHA. This work proved that the cultivation strategy used allowed the biological production of LA, reaching 37%w/w when the SHH was composed of 85% pentoses. In addition, the simultaneous biological production of LA and PHB was possible when the SHH was enriched with acetate (45% pentoses - 50% acetate). Finally, this study showed that the composition of the SHH impacts directly on the selected microorganism genus and the type and quantity of the value-added compounds obtained

Risks of using EDTA as an agent for trace metals dosing in anaerobic digestion of olive mill solid waste

26 Páginas; 5 Tablas; 1 FiguraLow concentrations of trace elements in many organic wastes recommend their supplementation in order to avoid potential limitations. Different chelating agents have been used to ensure an adequate trace metal pool in the soluble fraction, by forming dissolved complexes. Ethylenediaminetetraacetic acid (EDTA) is probably the most common, although several negative effects could be associated with its usage. Biomethane potential tests were performed using Olive Mill Solid Waste as the substrate, supplementing different combinations of Fe, Co, Ni, Ba, always under the presence of EDTA. Results show that Ni and Co slightly recovered biodegradability. However, Ba supplementation resulted in worsening the methane yield coefficient in all cases. High concentration of EDTA leaded to decrease in the activity of anaerobic digestion. High availability of EDTA induces the capture of trace metals like Co or Ni, key trace metals for anaerobic biomass activity. While supplementing trace metals, the addition of Ba and/or EDTA must be carefully considered.The authors are very grateful to the Spanish Ministry of Economy and competitiveness for funding this research through Project CTM2014-55095-R. The authors would also like to thank to the Marie Curie's International Research Staff Exchange Scheme (IRSES) “Renewable energy production through microalgae cultivation: closing material cycles” (PIRSES-GA-2011-295165) and to the Brasilian Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq – Process: 301020/2014-0) for providing financial support. David Jeison wishes to thank support provided by CRHIAM Centre (CONICYT/FONDAP/15130015).Peer reviewe