Enhancement of Cellulose Pellicle Production by Constitutively Expressing Vitreoscilla Hemoglobin in Acetobacter xylinum

摘要

Vitreoscilla hemoglobin (VHb) gene driven by the constitutive bla promoter was expressed in the cellulose-producing Acetobacter xylinum.The expressed VHb was biochemically active and could enhance cell growth in a shaken culture containing cellulase.VHb-expressing A.xylinum (VHb~+) exhibited a specific growth rate 50% higher than that of the host strain (VHb~-).Probably because of its faster growth rate,the size of tentacled cellulose beads produced by VHb~+ was about 20% of that produced by VHb~- after 2 days cultivation in a shake-flask.When cultured statically,the amount of cellulose pellicle produced by VHb~+ could be 2-fold that produced by VHb~-.Cellulose pellicle concentration of 11 g/L was obtained for VHb~+,whereas 6 g/L was obtained for VHb~- after 6 days of microaerobic incubation.