Degradation of Poly(3-hydroxybutyrate) and Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) by Some Soil Aspergillus spp.
Systematic screening of 45 soil fungi for degradation polyhydroxyalkanoic acids (PHAs) has led to the selection of 6 potent Aspergillus isolates belonging to A. flavus, A. oryzae, A. parasiticus, and A. racemosus. Degradation of PHAs as determined by tube assay method revealed that these Aspergillus spp. were more efficient in degrading poly(3-hydroxybutyrate) [P(3HB)] compared to copolymer of 3-hydroxybutyric acid and 3-hydroxyvaleric acid (P3HB-co-16% 3HV). Moreover, the extent of degradation in mineral base medium was much better than those in complex organic medium. For all the Aspergillus spp. tested, maximum degradation was recorded at a temperature of 37°C with significant inhibition of growth. The optimum pH range for degradation was 6.5–7.0 with degradation being maximum at pH 6.8. The extent of polymer degradation increased with increase in substrate concentration, the optimum concentration for most of the cultures being 0.4% and 0.2% (w/v) for P(3HB) and P(3HB-co-16%3HV) respectively. Supplementation of the degradation medium with additional carbon sources exerted significant inhibitory effect on both P(3HB) and P(3HB-co-16%3HV) degradation.
KeywordsPolyhydroxyalkanoate Poly(3-hydroxybutyrate) Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) Biodegradation Fungi Aspergillus
This work was supported by the financial assistance from the Council of Scientific and Industrial Research, New Delhi.
- 1.Steinbüchel A (1991) In: Byrom D (ed) Biomaterials, MacMillan Publishers, London, p 123Google Scholar
- 2.Brandl H, Gross RA, Lenz RW, Fuller RC (1990) Adv Biochem Eng Biotechnol 41:77Google Scholar
- 3.Brandl H, Bachofen R, Mayer J, Wintermantel E (1995) Can J Microbiol 41(suppl 1):143Google Scholar
- 4.Chowdhury AA (1963) Arch Microbiol 47:167Google Scholar
- 5.Delafield FP, Doudoroff N, Palleroni NJ, Lusty J, Contopoulos R (1965) J Bacteriol 90:1455Google Scholar
- 8.Mergaert J, Webb A, Anderson C, Wouters A, Swings J (1993) Appl Environ Microbiol 59:3233Google Scholar
- 14.Lepidi AA, Nuti MP, Bertoldi M (1972) Agric Ital (Pisa) 72:166Google Scholar
- 15.Neumier S (1994) Diploma Thesis. Universitat Regensburg. p 99Google Scholar
- 16.Mergaert J, Glorieux G, Hauben L, Storms V, Mau M, Swings J (1996) System Appl Microbiol 19:407Google Scholar
- 17.Matavulj M, Molitoris HP (1991) Abstr Tagung Sekt Mykol Dtsch Bot Ges, Bayreuth FRGGoogle Scholar
- 18.Kim DY, Rhee YH (2003) Appl Microbiol Biotechnol 61:300Google Scholar
- 19.Nam JS, Kim HC, Kim DY, Rhee YH (2002) Proc Int Symp Genet Ind Microorg 9:192Google Scholar
- 20.Matavulj M, Moss ST, Molitoris HP (1993) Proc Int Sym Bact PHA p 465Google Scholar
- 25.Pal S, Manna A, Paul AK (2000) Folia Microbiol 43:177Google Scholar
- 26.Malik KA, Claus D (1978) J Appl Bacteriol 45:143Google Scholar
- 27.Doi Y (1990) Microbial polyesters. VCH Publishers, New YorkGoogle Scholar
- 28.Scherer Y (1996) Ph. D. Thesis, University of Massachusetts, AhmerstGoogle Scholar
- 31.Neumeir S (1997) Ph. D. Thesis, Universitat Regensburg. p 148Google Scholar