ORCID Profile
0000-0002-8360-1404
Current Organisation
Universidade Nova de Lisboa Faculdade de Ciências e Tecnologia
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Publisher: Elsevier BV
Date: 2018
DOI: 10.1016/J.NBT.2017.08.007
Abstract: Polyhydroxyalkanoates (PHA) are biopolymers that can be produced by mixed microbial cultures using wastes or industrial by-products, which represent an economical and environmental advantage over pure culture processes. The use of alternate feedstocks enables using seasonal by-products, providing that the process is resilient to transient conditions. The mixed microbial communities of a 3-stage PHA producing system fed initially with molasses and then cheese whey were investigated through licon sequencing of the 16S rRNA gene. The transition in feedstock resulted in an adaptation of the acidogenic community, where Actinobacteria dominated with sugarcane molasses (up to 93% of the operational taxonomic units) and Firmicutes, with cheese whey (up to 97%). The resulting fermentation products profile also changed, with a higher fraction of HV precursors obtained with molasses than cheese whey (7.1±0.5 and 1.7±0.7 gCOD/L, respectively). As for the PHA storing culture, the genera Azoarcus, Thauera and Paracoccus were enriched with fermented molasses (average 89% of Bacteria). Later, fermented cheese whey fostered a higher ersity, including some less characterised PHA-storers such as the genera Paenibacillus and Lysinibacillus. Although the microbial community structure was significantly affected by the feedstock shift, the acidogenic and PHA storing performance of the 3-stage system was very similar once a pseudo steady state was attained, showing that a reliable level of functional redundancy was attained in both mixed cultures.
Publisher: Elsevier BV
Date: 07-2017
DOI: 10.1016/J.NBT.2016.07.001
Abstract: Polyhydroxyalkanoates (PHA) are a sustainable alternative to conventional plastics that can be obtained from industrial wastes/by-products using mixed microbial cultures (MMC). MMC PHA production is commonly carried out in a 3-stage process of acidogenesis, PHA culture selection and accumulation. This research focused on the possibility of tailoring PHA by controlling the acidogenic reactor operating conditions, namely pH, using cheese whey as model feedstock. The objective was to investigate the impact that dynamically varying the acidogenic pH, when targeting different PHA monomer profiles, had on the performance and microbial community profile of the anaerobic reactor. To accomplish this, an anaerobic reactor was continuously operated under dynamic pH changes, ranging from pH 4 to 7, turning to pH 6 after each change of pH. At pH 6, lactate and acetate were the dominant products (41-48% gCOD basis and 22-44% gCOD basis, respectively). At low pH, lactate production was higher while at high pH acetate production was favoured. Despite the dynamic change of pH, the fermentation product composition at pH 6 was always similar, showing the resilience of the process, i.e. when the same pH value was imposed, the culture produced the same metabolic products independently of the history of changes occurring in the system. The different fermentation product fractions led to PHAs of different compositions. The microbial community, analysed by high throughput sequencing of bacterial 16S rRNA gene fragments, was dominated by Lactobacillus, but varied markedly when subjected to the highest and lowest pH values of the tested range (4 and 7), with increase in the abundance of Lactococcus and a member of the Candidate Division TM7. Different bacterial profiles obtained at pH 6 during this dynamic operation were able to produce a consistent profile of fermentation products (and consequently a constant PHA composition), demonstrating the community's functional redundancy.
Location: Portugal
Location: Portugal
Location: Portugal
Location: No location found
No related grants have been discovered for Anouk F. Duque.