Development of biodegradable plastics by microorganisms

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Plastic wastes have caused a serious pollution problem, so that it is desirable to develop plastic materials unburden some to the natural environment on the earth. Increasing attention has recently been paid to microbially produced polymers such as poly-3-hydroxybutyrate (PHB) and polysaccharides due to their biodegradability. This report describes the production of PHB from 1,4-butanediol (1,4 BD) and poly(L-malic acid) (PMLA) from glucose by these microorganisms.1. Production of PHB from 1,4 BD and degradability of the PHB In the production of P (3HB-co-4HB) copolymer, 4HB is a proper raw material, but quite expensive. We succeeded in the efficient preparation of 4HB from 1,4 BD by Candida rugosa IFO 1364. Then P (3HB-co-4HB) was produced by Alcaligenes eutrophus from the 4HB as the carbon source. The film prepared with the copolymer was elastic and it was decomposed in soil at 30ﾟC after 12 weeks.2. Production of PMLA from glucose by Aureobasidium sp. and somephysicochemical properties of the PMLA. Newly isolated black yeasts, Aureobasidium sp. were found to produce an acidic polymer, which was identified to be poly(beta-L-malic acid) by various chemical analyses. The molecular weight of the PMLA was about 10,000. The experiments on culture conditions indicated that the addition of CaCO_3, Fe and Zn ions to culture media increases the yield of the PMLA.