Biodegradation of synthetic and biodegradable plastics by leachate microbiomes

Dissertação de mestrado em BiotecnologiaNos últimos anos, várias estratégias têm sido desenvolvidas para colmatar a acumulação de plásticos no ambiente, como a descoberta de novos microrganismos e enzimas que consigam eficientemente biodegradar plásticos. Neste trabalho, as comunidades microbianas de lixiviado, em aerobiose e anaerobiose em condições termófilas, foram estudadas pela sua capacidade de biodegradar polímeros não-biodegradáveis (PE (polietileno) e PET (politereftalato de etileno)) e biodegradáveis (PCL (policaprolactona e PHB/PBAT (polihidroxibutirato/poli (butileno adipato-co-tereftalato)). Esta biodegradação também foi testada utilizando sedimento marinho como inóculo, em condições aeróbicas, metanogénicas e sulfato-redutores em temperaturas mesófilas. As experiências com lixiviado demonstraram uma biodegradação completa com PCL em pó, em condições anaeróbicas e aeróbicas (103 ± 18 % e 99 ± 6 %, respetivamente), observando-se, também, uma biodegradação completa para o PCL em filme em condições anaeróbias (100 ± 0,2%), e uma biodegradação de 28 a 100% em condições aeróbias. PHB/PBAT demonstrou uma biodegradação parcial (24 % ± 0,2 %) em anaerobiose. Contudo, não se observou uma produção de metano/consumo de oxigénio significativa para o PE e PET, resultando numa baixa biodegradação. Mesmo assim, um dos ensaios demonstrou uma biodegradação aparente de 5 ± 2%, ao fim de 180 dias. As comunidades microbianas dos ensaios com PCL demonstraram ser distintas e diversas. Coprothermobacter estava presente em grande abundância nos ensaios aeróbios e anaeróbios e poderá ter estado diretamente ligado à biodegradação de PCL. Methanothermobacter demonstrou ser o microrganismo metanogénico mais abundante (mais de 55 % abundância relativa), tendo um papel importante na conversão do PCL a metano. Nos estudos com sedimento marinho, o PCL demonstrou ser biodegradado em condições aeróbias e sulfato-redutoras, mas não em condições metanogénicas. Até ao momento, a comunidade microbiana de sedimento não demonstrou ter capacidade para biodegradar PE e PET Estes resultados demostram que lixiviado e sedimento marinho são potenciais fontes de microrganismos com a capacidade de biodegradar PCL, sendo necessário mais estudos para isolar e caracterizar estas comunidades microbianas.In the last decades, various strategies have been developed to overcome the plastic waste problem, such as using biodegradable polymers, applying treatments that facilitate plastic degradation, and discovering novel microorganisms and enzymes that are capable of biodegrading complex polymers. This work explored leachate microbial communities in aerobic and anaerobic thermophilic conditions for their ability to biodegrade non-biodegradable (PE (polyethylene) and PET (polyethylene terephthalate)) and biodegradable (PCL (polycaprolactone) and PHB/PBAT (polyhydroxy butyrate/polybutylene adipate co-terephthalate blend)) polymers. Biodegradation was also tested with microbiomes from marine sediment, under aerobic, methanogenic, and sulphate-reducing mesophilic conditions. With leachate, complete biodegradation of powder PCL was observed both under anaerobic and aerobic conditions (103 ± 18 % and 99 ± 6 %, respectively). PCL films were fully converted to methane (100 ± 0,2%) under anaerobic conditions, and biodegradation under aerobic conditions ranged from 28 to 100 %. The blend PHB/PBAT was partially biodegraded under anaerobic conditions (24 ± 0,2 %). Generally, no significant methane production or oxygen consumption were detected in the assays with PE and PET, indicating no considerable biodegradation. Nevertheless, in one assay PE was apparently converted to methane (5 ± 2 % in 180 days), but further analyses are necessary to confirm this biodegradation. PCL-degrading microbial communities developed under aerobic and anaerobic assays were diverse and distinct. Coprothermobacter sp. was very abundant in aerobic and anaerobic incubations and was potentially involved in PCL biodegradation in both conditions. Methanothermobacter sp. was the most abundant methanogen (over 55 % relative abundance), being an important player during PCL conversion to methane. PCL was also biodegraded by the marine sediment, under aerobic and sulphate-reducing conditions, but not under methanogenic conditions. Thus far, the marine sediment microbiome did not biodegrade PE and PET. These results show that leachate and marine sediment microbiomes are potentially good sources of microorganisms with the ability to biodegrade PCL, and further attempts should be made to isolate key microorganisms, obtain efficient microbial consortia, facilitate microbial access to the polymers, and stimulate the activity of plastic-degrading microorganisms

Networks and the organisation of knowledge intensive sectors

This paper addresses the role of networks in the organisation of two different knowledge intensive sectors - biotechnology and software. Its main aim is to identify and explain the differences in the architecture of the networks, formal and informal, mobilised to access resources and competences by young entrepreneurial firms in those two sectors in Portugal. Then it discusses the diversity of the actual network topologies in the light of their contribution to the organisation of those sectors, taking into account their specific environment. For this purpose, it applies a methodology that permits to assemble a vast array of data capturing the nature and contents of the range of relationships through which key innovation resources flow into the firms. The results show that, when a detailed analysis is carried out, significant inter-sectoral differences emerge, both in the network diagrams and in the measures of composition and structure. We argue that those different topologies make sense regarding the empirical literature and shed light on the specific organisation of the sectors, with their strengths, weaknesses and policy-driven influences

Control of pathogenic and spoilage microorganisms from cheese surface by whey protein films containing malic acid, nisin and natamycin

The inhibitory effects of nisin, natamycin and malic acid, incorporated in whey protein films with pH 3, were investigated alone or with addition of sucrose esters, Tween80 or EDTA. Water vapour permeability measurements and mechanical and rheological tests were also assessed. EDTA and Tween80 did not sig- nificantly (P < 0.05) influence the inhibitory activity of films against Pseudomonas aeruginosa and Yarrow- ia lipolytica in contrast with the improved effect against Listeria monocytogenes, Penicillium commune and Penicillium chrysogenum. Sucrose esters reduced significantly (P < 0.05) the inhibitory effect for Y. lipoly- tica and Penicillium spp. The present work provides an antimicrobial film formulation with potential to be a hurdle against spoilage and pathogenic microorganisms isolated from cheese surface

Assessment of the Availability of Forest Biomass for Bioenergy Production in Southwest Portugal.

In 2014, Portugal was the seventh largest pellets producer in the World. Since the shortage of raw material is one of the major obstacles that the Portuguese sellets market faces, the need for a good assessment of biomass availability for energy purposes at both country and regional levels is reinforced. This work uses a Geographical Information System environment and remote sensing data to assess the availability and sustainability of forest biomass residues in a management unit with around 940 ha of maritime pine forest. The period considered goes from 2004 to 2015. The study area is located in Southwestern Portugal, close to a pellets factory; therefore the potential Contribution of the residual biomass generated in the management unit to the production of pellets is evaluated. An allometric function is used for the estimation of maritime pine above ground biomass. With this estimate, and considering several forest operations, the residual biomass available was assessed, according to stand composition and structure. This study shows that, when maritime pine forests are managed to produce wood, the amount of residues available for energy production is small (an average of 0.37 t ha -1  year -1 were generated in the study area between 2004 and 2015). As a contribution to the sustainability of the Portuguese pellets industries, new management models for maritime pine forests may be developed. The effect of the pinewood nematode on the availability of residual biomass can be clearly seen in this study. In the management unit considered, cuts were made to prevent dissemination of the disease. This contributes to a higher availability of forest residues in a specific period of time, but, in the medium term, they lead to a decrease in the amount of residues that can be used for energy purposes

Properties of whey protein-based films containing organic acids and nisin to control Listeria monocytogenes

Whey protein isolate and glycerol were mixed to form a matrix to incorporate antimicrobial agents and produce edible films with antimicrobial activity against Listeria monocytogenes strains isolated from cheeses. Various organic acids were used to decrease pH down to approximately 3. In a preliminary assay without nisin, the effect of each organic acid was evaluated with respect to the rheological properties of the film solutions and the inhibitory and mechanical properties of the films. Lactic, malic, and citric acids (3%, wt/vol), which were used in a subsequent study of their combined inhibitory effect with nisin (50 IU/ml), had significantly higher antilisterial activity (P , 0.05) compared with the control (2 N HCl, 3% [wt/vol], with nisin). The largest mean zone of inhibition was 4.00 6 0.92 mm for malic acid with nisin. Under small-amplitude oscillatory stress, the proteinglycerol- acid film solutions exhibited a predominantly viscous behavior or a weak gel behavior, with the storage modulus (G9) slightly higher than the loss modulus (G0). The malic acid–based solution was the only one whose viscosity was not influenced by the addition of nisin. The addition of nisin resulted in a nonsignificant (P . 0.05) increase in the percentage of elongation at break. Results from tensile and puncture stress were variable, but in general no significant differences were found after the incorporation of nisin. The overall results support the use of malic acid with nisin to produce effective antimicrobial films to control L. monocytogenes growth

Chapter Solid Biomass from Forest Trees to Energy: A Review

Among the different terrestrial ecosystems, forests are the most important biomass carbon producers and the ones that store the most standing biomass carbon. Consequently, they are also the major source of biomass for energy. Forest biomass has been used as a fuel from early times, and from the late twentieth century onward, there has been a renewed interest in its use to produce heat and electricity. The interest in forest biomass as an energy source relates to some of its features, such as relative abundance and uniformity worldwide and neutrality of CO2 emissions. Nonetheless, its use is not free of risks, mostly related with the sustainability of the forest systems and their productions. This study reviews the state of the art of the forest sources of biomass for energy, their assessment, their properties as a fuel, as well as the conversion technologies used in the most common energy applications

Solid Biomass from Forest Trees to Energy: A Review

Among the different terrestrial ecosystems, forests are the most important biomass carbon producers and the ones that store the most standing biomass carbon. Consequently, they are also the major source of biomass for energy. Forest biomass has been used as a fuel from early times, and from the late twentieth century onward, there has been a renewed interest in its use to produce heat and electricity. The interest in forest biomass as an energy source relates to some of its features, such as relative abundance and uniformity worldwide and neutrality of CO2 emissions. Nonetheless, its use is not free of risks, mostly related with the sustainability of the forest systems and their productions. This study reviews the state of the art of the forest sources of biomass for energy, their assessment, their properties as a fuel, as well as the conversion technologies used in the most common energy applications

Rheology methods as a tool to study the impact of whey powder on the dough and breadmaking performance of wheat flour

Considering the nutritional value, whey is an excellent ingredient for the development of food products, in line with the concept of a circular economy for the reuse of industry by-products. The main objective of this work was to evaluate the impact of the whey addition on the rheology of wheat flour dough and breadmaking performance, using both empirical and fundamental methods. Di erent levels of commercial whey powder (0%, 12%, 16% and 20% w/w) were tested in a bread formulation previously optimized. Dough mixing tests were performed using Micro-doughLab and Consistograph equipment, to determine the water absorptions of di erent formulations and evaluate empirical rheology parameters related to mixing tolerances. Biaxial extension was applied by the Alveograph to simulate fermentation during the baking process. Fermented doughs were characterized in a Texturometer using penetration and extensibility tests, and by small amplitude oscillatory shear (SAOS) measurements, a fundamental rheology method, in a Rheometer applying frequency sweeps. Loaf volume and firmness were used to study the breadmaking quality. Despite a negative impact on the empirical rheology parameters of the dough and poorer baking results, the use of this by-product should be considered for nutritional and sustainability reasons. In addition, significant correlations (r2 > 0.60) between the dough rheology parameters obtained from the empirical measurements were established. Changes in the gluten structure were not accurately detected by the SAOS measurements and Texture Profile Analysis of the doughs, and a correlation between fundamental and empirical measurements was not found. Consistograph or Micro-doughLab devices can be used to estimate bread firmness. Extensional tests in the Texturometer, using SMS/Kie er Dough and Gluten Extensibility Rig, may predict loaf volumeinfo:eu-repo/semantics/publishedVersio