scholarly journals The Microbial Production of Polyhydroxyalkanoates from Waste Polystyrene Fragments Attained Using Oxidative Degradation

Polymers ◽  
2018 ◽  
Vol 10 (9) ◽  
pp. 957 ◽  
Author(s):  
Brian Johnston ◽  
Iza Radecka ◽  
David Hill ◽  
Emo Chiellini ◽  
Vassilka Ilieva ◽  
...  
Keyword(s):  
Economic Value ◽  
Carbon Sources ◽  
Oxidative Degradation ◽  
Genetic Profile ◽  
Waste Plastics ◽  
Stability Robustness ◽  
Rich Media ◽  
Cupriavidus Necator H16 ◽  
New Generation ◽  
Potential Carbon

Excessive levels of plastic waste in our oceans and landfills indicate that there is an abundance of potential carbon sources with huge economic value being neglected. These waste plastics, through biological fermentation, could offer alternatives to traditional petrol-based plastics. Polyhydroxyalkanoates (PHAs) are a group of plastics produced by some strains of bacteria that could be part of a new generation of polyester materials that are biodegradable, biocompatible, and, most importantly, non-toxic if discarded. This study introduces the use of prodegraded high impact and general polystyrene (PS0). Polystyrene is commonly used in disposable cutlery, CD cases, trays, and packaging. Despite these applications, some forms of polystyrene PS remain financially and environmentally expensive to send to landfills. The prodegraded PS0 waste plastics used were broken down at varied high temperatures while exposed to ozone. These variables produced PS flakes (PS1–3) and a powder (PS4) with individual acid numbers. Consequently, after fermentation, different PHAs and amounts of biomass were produced. The bacterial strain, Cupriavidus necator H16, was selected for this study due to its well-documented genetic profile, stability, robustness, and ability to produce PHAs at relatively low temperatures. The accumulation of PHAs varied from 39% for prodegraded PS0 in nitrogen rich media to 48% (w/w) of dry biomass with the treated PS. The polymers extracted from biomass were analyzed using nuclear magnetic resonance (NMR) and electrospray ionization tandem mass spectrometry (ESI-MS/MS) to assess their molecular structure and properties. In conclusion, the PS0–3 specimens were shown to be the most promising carbon sources for PHA biosynthesis; with 3-hydroxybutyrate and up to 12 mol % of 3-hydroxyvalerate and 3-hydroxyhexanoate co-monomeric units generated.

scholarly journals Adaptive Laboratory Evolution of Cupriavidus necator H16 for Carbon Co-Utilization with Glycerol

2019 ◽  
Vol 20 (22) ◽  
pp. 5737 ◽  
Author(s):  
Miriam González-Villanueva ◽  
Hemanshi Galaiya ◽  
Paul Staniland ◽  
Jessica Staniland ◽  
Ian Savill ◽  
...  
Keyword(s):  
Type Strain ◽  
Wild Type Strain ◽  
Carbon Sources ◽  
Strain Engineering ◽  
Cupriavidus Necator ◽  
Superior Performance ◽  
Wild Type ◽  
Adaptive Laboratory Evolution ◽  
Laboratory Evolution ◽  
Cupriavidus Necator H16

Cupriavidus necator H16 is a non-pathogenic Gram-negative betaproteobacterium that can utilize a broad range of renewable heterotrophic resources to produce chemicals ranging from polyhydroxybutyrate (biopolymer) to alcohols, alkanes, and alkenes. However, C. necator H16 utilizes carbon sources to different efficiency, for example its growth in glycerol is 11.4 times slower than a favorable substrate like gluconate. This work used adaptive laboratory evolution to enhance the glycerol assimilation in C. necator H16 and identified a variant (v6C6) that can co-utilize gluconate and glycerol. The v6C6 variant has a specific growth rate in glycerol 9.5 times faster than the wild-type strain and grows faster in mixed gluconate–glycerol carbon sources compared to gluconate alone. It also accumulated more PHB when cultivated in glycerol medium compared to gluconate medium while the inverse is true for the wild-type strain. Through genome sequencing and expression studies, glycerol kinase was identified as the key enzyme for its improved glycerol utilization. The superior performance of v6C6 in assimilating pure glycerol was extended to crude glycerol (sweetwater) from an industrial fat splitting process. These results highlight the robustness of adaptive laboratory evolution for strain engineering and the versatility and potential of C. necator H16 for industrial waste glycerol valorization.

scholarly journals The nature of carbon flux in various ecosystem types in the Biduk-Biduk Karst Region, Berau District, East Kalimantan

2019 ◽  
Vol 76 ◽  
pp. 04005
Author(s):  
Danardono Danardono ◽  
Eko Haryono ◽  
Margareta Widyastuti
Keyword(s):  
Carbon Sequestration ◽  
Soil Respiration ◽  
Tropical Forest ◽  
Economic Value ◽  
Carbon Stocks ◽  
Karst Region ◽  
Litter Fall ◽  
Closed Chamber ◽  
East Kalimantan ◽  
Potential Carbon

Biduk-Biduk Karst Region has great potential to absorb and store organic carbon in vegetation and soil as well as to absorb inorganic carbon through the process of dissolution. The area has important economic value in supporting the REDD Program in Berau District. The purpose of this study is (1) to identify the amount of carbon stocks in various ecosystems; and (2) to identify the amount of carbon uptake in various ecosystems in the study area. Carbon stocks are computed based on four carbon sinks, i.e., above ground biomass, underground biomass, litter, and soil organic matter using the standard measurement method of SNI 7724: 2011. Carbon sequestration is calculated based on the input of carbon from the atmosphere to ecosystems through litter fall and karstification process and the output of carbon from the ecosystem to the atmosphere through soil respiration. Litter fall is measured using the litter trap method. Karstification is measured with standard limestone tablet method. Soil respiration is calculated with the closed chamber method. The results show that the ecosystems in the Biduk-Biduk Karst Region have a potential carbon stock of 4,800.92 tons/ha with the largest value in the secondary tropical forest of 732.6 tons/ha and the lowest value in the teak forest plantation of 358.2 tons/ha. Ecosystems in the Biduk-Biduk Karst Region have a potential carbon sequestration of 37.33 tons/ha/year with the largest contribution in the primary tropical forest of 7,63 tons/ha/year.

scholarly journals Produksi dan stabilisasi desaturase dari Absidia corymbifera Production and stabilization of desaturases from Absidia corymbifera

2016 ◽  
Vol 70 (2) ◽  
Author(s):  
. TRI-PANJI ◽  
. SUHARYANTO ◽  
A W PAULUS ◽  
K SYAMSU ◽  
A M FAUZI
Keyword(s):  
Fatty Acids ◽  
Linoleic Acid ◽  
Culture Filtrate ◽  
Unsaturated Fatty Acids ◽  
Storage Temperature ◽  
Lipid Extraction ◽  
Economic Value ◽  
Carbon Sources ◽  
Carbon Chain ◽  
Absidia Corymbifera

SummaryDesaturases are enzymes which catalyze desaturation process on carbon chain of fatty acids into unsaturated fatty acids useful for healthy oil. Desaturases could be produced from Absidia corymbifera and applied for increasing unsaturation level and crude palm oil (CPO) quality. Desaturases have been known as very unstable enzymes. The objective this research was to determine carbon sources and culture time for optimum desaturase production, fatty acid composition resulted from desaturase bioconversion, and methods for stabilization of desaturase from A. corymbifera. Results showed that desaturases from A. corymbifera are intracellular enzymes that reached the highest activity in Serrano-Careon medium with C sources of a mixture of sucrose and paraffin (0.14 U/mL) and C sources of molasses (0.11 U/mL) incubated for 76 and 120 hours respectively. Activity of ∆6 and ∆12 desaturases have been detected in culture filtrate of A. corymbifera. Activiy of ∆12 desaturase was confirmed by increasing of linoleic acid in CPO incubated with culture filtrate and biomass extract, while activity of ∆6 was detected by its conversion as much as 66.48 % linoleic acid into gamma linolenic acid (GLA) that having high economic value. Precipitation of culture filtrate and lipid extraction of biomass were unable to stabilize desaturases. Desaturase degradation rate could be inhibited by isolation and washing of microsome fraction using high salt buffer. This method could stabilize desaturases 70-80% from initial activity at storage temperature 25o C and 50 o C for 6 hours. RingkasanDesaturase merupakan enzim yang berperan dalam proses desaturasi rantai karbon asam lemak menjadi asam lemak tak jenuh yang banyak manfaatnya bagi kesehatan. Desaturase dapat dihasilkan dari Absidia corymbifera dan diamplifikasikan untuk peningkatan ketidakjenuhan dan kualitas minyak sawit mentah (CPO). Enzim desaturase dikenal sangat tidak stabil. Penelitian bertujuan menetapkan sumber karbon dan waktu kultur yang memberikan aktivitas desaturase tertinggi, komposisi asam lemak hasil konversi desaturase dan cara menstabilkan desaturase dari A. corymbifera. Hasil penelitian menunjukkan bahwa desaturase dari A. corymbifera merupakan enzim intraselular yang mencapai aktivitas tertinggi pada medium Serrano-Careon dengan sumber karbon campuran sukrosa dan parafin (0,14 U/mL) dan sumber karbon molases (0,11 U/mL) masingmasing pada inkubasi selama 76 dan 120 jam. Aktivitas ∆6 dan ∆12 desaturase terdeteksi pada cairan fermentasi A. corymbifera. Aktivitas ∆12 desaturase terdeteksi dari peningkatan persentase asam linoleat pada CPO yang telah diinkubasi dengan cairan fermentasi atau ekstrak biomassa, sedangkan aktivitas ∆6 desaturase terdeteksi dari dikonversinya sebesar 66,48% asam linoleat menjadi asam gamma linolenat (GLA) yang memiliki potensi nilai ekonomis lebih tinggi. Pengendapan filtrat kultur fermentasi dan ekstraksi lipida biomassa tidak mampu menstabilkan desaturase. Laju degradasi desaturase dapat dihambat dengan cara isolasi dan pencucian fraksi mikrosom dengan bufer garam. Cara tersebut dapat mempertahankan aktivitas desaturase 70–80% pada penyimpanan suhu 25o C dan 50o C selama enam jam.

scholarly journals Host engineering for improved valerolactam production in Pseudomonas putida

2019 ◽  
Author(s):  
Mitchell G. Thompson ◽  
Luis E. Valencia ◽  
Jacquelyn M. Blake-Hedges ◽  
Pablo Cruz-Morales ◽  
Alexandria E. Velasquez ◽  
...  
Keyword(s):  
Metabolic Engineering ◽  
Carbon Source ◽  
Pseudomonas Putida ◽  
Aromatic Compounds ◽  
Sole Carbon Source ◽  
Carbon Sources ◽  
Shotgun Proteomics ◽  
Rich Media ◽  
Amide Hydrolase

ABSTRACTPseudomonas putida is a promising bacterial chassis for metabolic engineering given its ability to metabolize a wide array of carbon sources, especially aromatic compounds derived from lignin. However, this omnivorous metabolism can also be a hindrance when it can naturally metabolize products produced from engineered pathways. Herein we show that P. putida is able to use valerolactam as a sole carbon source, as well as degrade caprolactam. Lactams represent important nylon precursors, and are produced in quantities exceeding one million tons per year[1]. To better understand this metabolism we use a combination of Random Barcode Transposon Sequencing (RB-TnSeq) and shotgun proteomics to identify the oplBA locus as the likely responsible amide hydrolase that initiates valerolactam catabolism. Deletion of the oplBA genes prevented P. putida from growing on valerolactam, prevented the degradation of valerolactam in rich media, and dramatically reduced caprolactam degradation under the same conditions. Deletion of oplBA, as well as pathways that compete for precursors L-lysine or 5-aminovalerate, increased the titer of valerolactam from undetectable after 48 hours of production to ~90 mg/L. This work may serve as a template to rapidly eliminate undesirable metabolism in non-model hosts in future metabolic engineering efforts.

scholarly journals PHA Production and PHA Synthases of the Halophilic Bacterium Halomonas sp. SF2003

2020 ◽  
Vol 7 (1) ◽  
pp. 29
Author(s):  
Tatiana Thomas ◽  
Kumar Sudesh ◽  
Alexis Bazire ◽  
Anne Elain ◽  
Hua Tiang Tan ◽  
...  
Keyword(s):  
Marine Bacterium ◽  
Carbon Sources ◽  
Halophilic Bacterium ◽  
Growth Conditions ◽  
In Silico Study ◽  
Carbon Substrates ◽  
Cupriavidus Necator H16 ◽  
Pha Production

Among the different tools which can be studied and managed to tailor-make polyhydroxyalkanoates (PHAs) and enhance their production, bacterial strain and carbon substrates are essential. The assimilation of carbon sources is dependent on bacterial strain’s metabolism and consequently cannot be dissociated. Both must wisely be studied and well selected to ensure the highest production yield of PHAs. Halomonas sp. SF2003 is a marine bacterium already identified as a PHA-producing strain and especially of poly-3-hydroxybutyrate (P-3HB) and poly-3-hydroxybutyrate-co-3-hydroxyvalerate (P-3HB-co-3HV). Previous studies have identified different genes potentially involved in PHA production by Halomonas sp. SF2003, including two phaC genes with atypical characteristics, phaC1 and phaC2. At the same time, an interesting adaptability of the strain in front of various growth conditions was highlighted, making it a good candidate for biotechnological applications. To continue the characterization of Halomonas sp. SF2003, the screening of carbon substrates exploitable for PHA production was performed as well as production tests. Additionally, the functionality of both PHA synthases PhaC1 and PhaC2 was investigated, with an in silico study and the production of transformant strains, in order to confirm and to understand the role of each one on PHA production. The results of this study confirm the adaptability of the strain and its ability to exploit various carbon substrates, in pure or mixed form, for PHA production. Individual expression of PhaC1 and PhaC2 synthases in a non-PHA-producing strain, Cupriavidus necator H16 PHB¯4 (DSM 541), allows obtaining PHA production, demonstrating at the same time, functionality and differences between both PHA synthases. All the results of this study confirm the biotechnological interest in Halomonas sp. SF2003.

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