Polyhydroxyalkanoic acids

Hypochlorite digestion method for efficient recovery of PHB from Alcaligenes faecalis

“…This continuous decline in the amount of PHB from 5.6 gL -1 to 0.7 gL -1 indicated the intracellular mobilization of PHB by the organism. PHB producing microorganisms are reported to utilize the intracellular PHB as reserve carbon and energy when the nutrients are exhausted from medium [11]. A. faecalis also possesses PHB depolymerase, which help in intracellular mobilization of PHB [10][11][12].…”

“…Time of extraction is equally important for the recovery of PHA, because during prolonged incubation under nutrient limiting conditions, PHB is utilized as a stored carbon and energy in presence of PHB depolymerase [10][11][12].…”

Bacterial polyhydroxyalkanoates-eco-friendly next generation plastic: Production, biocompatibility, biodegradation, physical properties and applications

“…A wide range of taxonomically and physiologically different natural bacteria and some archae accumulate PHAs as storage reserve materials and deposit them as insoluble granules in the cytoplasm (10,11,69,70,83,84). After the discovery of PHB from the bacterium B. megaterium (18), over 300 different bacteria, including Gram-negative and -positive species, have been reported to accumulate various PHAs (11,28,83,86,87).…”

“…PHAs are a class of polyesters of various hydroxycarboxylic acids, which are produced and accumulated by a large number of bacteria under unbalanced growth conditions as intracellular hydrophobic inclusions of carbon and energy storage compounds in the cytoplasm to levels as high as 90-97% of the cell dry weight (4)(5)(6)(7)(8)(9) or as an electron sink mechanism for redundant reducing power under the condition of limiting nutritional elements such as N, P, S, O or Mg in the presence of excess carbon source (10)(11)(12)(13). They are synthesized as byproducts not the major ones when there is no sufficient nutrient to promote their growth and do not play an essential role in development of the producing organisms, but convey survival in the biological community and environment, therefore, microbial PHAs are secondary metabolites (14).…”

Produção biotecnológica de poli-hidroxialcanoatos para a geração de polímeros biodegradáveis no Brasil

“…O termo PHA (Figuras 1 e 2) é aplicado a uma família de poliésteres acumulados por diversas bactérias, na forma de grânulos intracelulares de reserva de carbono, energia e equivalentes redutores 23,24 . Em geral, a síntese de PHA por bactérias em um meio nutritivo ocorre quando há excesso de fonte de carbono e a limitação de pelo menos um nutriente necessário à multiplicação das células (N, P, Mg, Fe etc.)…”