Hydroxylation of biphenyl by Aspergillus parasiticus: Approaches to yield improvment in fermenter cultures

John C. Cox, John H. Golbeck

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We carried out experiments designed to increase the rate of production of 4,4′‐dihydroxybiphenyl (biphenol) from biphenyl by Aspergillus parasiticus. We show that 0.5 mg/ml biphenyl, the substrate for the reaction, significantly inhibits growth of the organism and that at 0.04 mg/ml, 2‐hydroxybiphenyl or 4‐hydroxybiphenyl (an intermediate of the reaction) strongly inhibit oxygen uptake, probably by inhibition of mitochondrial electron transport. Both factors may contribute to the low hydroxylation rates observed previously [J. H. Golbeck and J. C. Cox, Biotechnol. Bioeng., 26, 434 (1984)]. We therefore adapted the organism to the presence of 0.08 mg/ml 2‐ and 4‐hydroxybiphenyl in the growth medium and found that cultures of adapted strains hydroxylated biphenyl at rates ca. three‐fold faster than control cultures. Once the fungal mycelia were grown, they could be recycled at least twice into fresh fermentation broth. Recycled organisms were capable of hydroxylating biphenyl more rapidly than cells in the primary fermentation culture and there was no lag period between introduction of biphenyl and the onset of hydroxylation. Cell recycle thus results in a considerable saving in carbon costs and fermentation time.

Original languageEnglish (US)
Pages (from-to)1395-1402
Number of pages8
JournalBiotechnology and bioengineering
Issue number10
StatePublished - Oct 1985

All Science Journal Classification (ASJC) codes

  • Biotechnology
  • Bioengineering
  • Applied Microbiology and Biotechnology


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