Brinda Devi A, Valli Nachiyar C, Kaviyarasi T. Bacillus cereus mediated synthesis of green plastics-Polyhydroxybutyrate. J Pure Appl Microbiol 2014;8:4143-7.
Due to the absence of efficient methods for safe disposal of these synthetic polymers, they often end up accumulated in the environment, posing an ever-increasing ecological threat to flora and fauna .In Saudi Arabia, approximately 12 million tons of municipal solid wastes are produced annually, consisting of 40% organic wastes, 20% paper wastes, and 12–15% of plastic products .
Microbial production of poly(hydroxybutyrate) ..
AB - In the Satake Centre for Grain Process Engineering we are developing cereal-based biorefining strategies for the production of biofuels, biodegradable plastics and platform chemicals. Cereal grains are complex biological entities and we target the exploitation of all cereal components providing both value-added end-products and precursors for chemical synthesis. Hydrolysis of natural polymers (e.g. starch, protein) contained in cereals requires supply of a range of hydrolytic enzymes (e.g. amylase, protease), which are produced by fungal bioconversions. On-site production of these enzymes would result in the production of a high amount of fungal biomass. Fungal autolysis can be used to bioconvert this low-cost byproduct into a nutrient-rich supplement (fungal extract) for microbial bioconversions. Mixing fungal extracts with cereal hydrolysates results in nutrient-complete microbial feedstocks. Optimising the exploitation of protein in cereal grains would enable the provision of optimum amounts of free amino acids and peptides to subsequent microbial bioconversions and the extraction of the remaining protein as a value-added co-product with various current (food) and potential (biodegradable plastics) market outlets. The use of amino acids and peptides would enhance productivities (e.g. polyhydroxybutyrate, succinic acid) and, in certain cases, production yields (e.g. polyhydroxybutyrate) improving significantly current fermentation practices that exploit only the starch component in cereal grains. In addition, the exploitation of all cereal components and low-cost by-product streams produced in a cereal-based biorefinery will result in waste minimisation and maximisation of carbon as well as other nutrient utilisation from the original cereal grain. This work will present different feedstock formulation strategies based on the production of wheat hydrolysates and fungal extracts for the microbial production of polyhydroxybutyrate and succinic acid.
The Thiol-Michael Addition Click Reaction: A Powerful …
Biobased plastics are made from renewable resources instead of non-renewable petroleum based resources. These renewable resources can include corn, potatoes, rice, soy, sugarcane, wheat, and vegetable oil. Biobased plastics are made by creating plastic polymers from these materials, through either chemical or biological processes. Examples of these types of plastics are polylactic acid (PLA) – derived from starch, polyhydroxybutyrate (PHB) – derived through microbial synthesis, and biobased polyethylene (bioPE) – produced from sugar cane.
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Biological cells employ compartmentalization to overcome many difficult metabolic and physiological challenges. Eukaryotes mainly use membrane-bound organelles to sequester and control the flow of metabolites, store genetic information and segregate protein processing and export. In contrast, the majority of prokaryotes do not possess intracytoplasmic membrane systems and instead rely on protein-based approaches to achieve spatial control. However, certain specialized membrane compartments have been identified in specific bacterial strains, including polyphosphate-storing acidocalcisomes, photosynthetic thylakoids in cyanobacteria, magnetosomes in magnetotactic bacteria and pirellulosomes and anammoxosomes in morphologically complex Planctomycetes (Figure 1). Important examples for protein-based organelles include bacterial microcompartments (BMCs) like the CO2-fixing carboxysome, ferritins involved in iron homeostasis and maintaining redox balance and functionally diverse encapsulin nanocompartments (Figure 1). Encapsulating enzymes or biosynthetic pathways in semi-permeable protein organelles can increase the local concentrations of metabolites and enzymes, prevent the loss of toxic or volatile intermediates and create unique microenvironments necessary for the proper functioning of specialized enzymes. In addition, encapsulation allows for incompatible reactions and processes to take place in a single cell at the same time.
Journal of Macromolecular Science, Part A ..
Giessen, TW, Silver, PA. (2016). Converting a natural protein compartment into a nanofactor for the size-constrained synthesis of antimicrobial silver nanoparticles. ACS Synth. Biol. 5(12), 1497-1504.