Production of copolyesters of 3-hydroxybutyrate and 3-hydroxyvalerate by Alcaligenes eutrophus from butyric and pentanoic acids

Abstract

IntroductionThe bacterial copolyester of 3-hydroxybutyrate (3HB) and 3-hydroxyvalerate (3HV) has attracted industrial attention as a possible candidate for large-scale biotechnological production, since the copolyester is an environmentally degradable thermoplastic'). The copolyester has been produced from propionic acid in Alcaligenes eutrophus, and the range of compositions has been shown to vary from 0 to 47 mol-Vo 3HVRecently, we have found that copolyesters with a wide range of compositions up to 90 mol-qo of 3HV units are produced in A . eutrophus by using pentanoic acid as carbon source4). This communication reports the biosynthesis of an interesting terpolyester of 3-hydroxybutyrate (3HB), 3-hydroxyvalerate (3HV), and Shydroxyvalerate (5HV) in A . eutrophus from 5-chloropentanoic and pentanoic acids. Experimental partA. eutrophus (NCIB 11599) was first grown at 30°C in a nutrient-rich medium (100 cm3) containing 1,0 g of yeast extract, 1,0 g of polypeptone, 0,5 g of meat extract, and 0,5 g of (NH&S04. The cells were harvested after 24 h and washed with water. Under these culture conditions an accumulation of polyesters in the cells was not observed. To promote polyester synthesis, about 0,4 g quantities of the washed cells were transferred into a nitrogen-free mediums) containing 5-chloropentanoic acid (ClCH2CH2CH2CH2COOH) and pentanoic acid (CH,CH2CH2CH2COOH). The cells were cultivated in this medium (100 cm3, pH = 7 3 ) for 48 h at 30 "C, harvested by centrifugation, washed with acetone, and finally dried under vacuum at room temperature. Polyesters were extracted from the dried cells with hot chloroform in a Soxhlet apparatus and purified by reprecipitation with hexane.The ' H NMR spectra of polyester samples were recorded on a JEOL GX-500 spectrometer operating at 500 MHz, using a CDCl, solution of polyester (5 mg/cm3). The spectra were obtained at 27OC, 45 pulse ( 3 3 ps), 6,O s pulse repetition, 7000 Hz spectral width, 32K data points, and 128 accumulations. The I3C NMR spectra of polyesters were recorded on a JEOL FX-100 spectrometer operating at 25 MHz, using a CDCl, solution of polyester (50 mg/cm3). The spectra were obtained at 27 "C, 45 O pulse (8,5 ps), 5,O s pulse repetition, 5000 Hz spectral width, 8 K data points, and 10000 accumulations. \ 0173-2803/87/$01 .OO8 h) Tab. 1. Biosynthesis of terpolyesters of 3-hydroxybutyrate (3HB), 3-hydroxyvalerate (3HV), and 5-hydroxyvalerate (5HV) in Alculigenes eutrophus at 3OoC Sample Wt. of carbon sourcea) in g Wt. of dry Polyester Polyester compositionc) in mol-yo [tll d, cells in g contentb)

Biosorption of Heavy Metal Ions onRhodobacter sphaeroidesandAlcaligenes eutrophusH16

“…They were grown in a batch to the late-exponential growth stage in nutrient rich medium (23). The cells were harvested, inactivated in an autoclave at 120℃ for 15 min, and washed three times with distilled water.…”

“…The use of nonliving bacteria for biosorption process has the obvious advantages of being inexpensive and easy to handle (17). In addition, purple bacteria have recently become very promising tools for purifying waste waters and gases (18)(19)(20)(21), and hydrogen bacteria have been used for the production of biodegradable polyester (22)(23)(24)(25).…”

Cloning and expression of the PHA synthase gene from a locally isolated Chromobacterium sp. USM2

“…High 3HV composition has been achieved using wild-type C. necator from selected 3HV-precursors or mixtures of these precursors with sugar. However, the high 3HV composition is mostly achieved by feeding higher concentration of precursors, up to 4-20 g/L (Doi et al, 1988;Ramsay et al, 1990;Madden et al, 1998;Volova and Kalacheva, 2005). The ability of the PHA synthase of Chromobacterium sp.…”

Thin Layer Drying Characteristics of Sweet Potato Starch Based Films and Mathematical Modelling

“…In order to solve the problems generated by plastic waste, particularly by disposable commodities, many efforts have been made to develop environment friendly materials [2,3]. The treatment of waste plastics has become a serious problem because of the difficulty of ensuring reclaimed land and burning by incineration [4]. The industry is now facing ecological and legislative issues for handling plastic raw materials and finished products [5].…”