Detection of chitinolytic activities in culture filtrates of the <i>T. virens</i> strains.

<p><i>N-</i>acetyl-ß-D-glucosaminidase, chitobiosidase and endochitinase activities of the wild type strain <i>Tv.</i>223 and the five chitinase-deficient mutants ?<i>Tvnag1</i>, ?<i>Tvnag2</i>, ?<i>Tvnag1</i>?<i>Tvnag2,</i> S.pNO8::<i>hph,</i> and S.pOf28::<i>hph</i> were determined by enzymatic hydrolysis of the chitinase-specific substrates 4-Nitrophenyl <i>N</i>-acetyl-ß-D-glucosaminide, 4-Nitrophenyl N,N’-diacetyl-ß-D-chitobioside and 4-Nitrophenyl ß-D-N,N’,N’’-triacetylchitotriose, respectively. Substrate hydrolysis releases <i>p</i>-nitrophenol which, upon ionization in basic pH, can be measured colorimetrically at 405 nm. Protein concentrations of the extracts were adjusted to 20 µg.mL⁻¹ prior to enzyme assays. Histograms are the means of three replicate values with standard deviations. One unit of the activity releases 1.0 µmole of <i>p-</i>nitrophenol from the appropriate substrate per minute at pH 4.8 and 37°C. Letters denote the results of a <i>t</i>-test for comparison of means. Bars with different letter(s) are significantly different at 95% confidence level.