TABLE 1.

Influence of growth conditions on the expression of glucuronidase by P. cellulosa

Carbohydrate added to Luria-Bertani growth mediuma	Enzyme activityb
	α-Glucuronidasec	β-Glucuronidased
None	NDe	ND
4-O-Methyl-d-glucuronoxylan	45 ± 5	32 ± 4
Oat spelt xylan	75 ± 6	60 ± 6
Wheat arabinoxylan	32 ± 3	33 ± 7
Rye arabinoxylan	51 ± 6	41 ± 7
Oat spelt xylan and glucose	ND	ND
Glucuronic acid	ND	ND
β-Glucan	ND	ND

^aCarbohydrates were each added to a final concentration of 0.2%.

^bα-Glucuronidase and β-glucuronidase activities, expressed as nanomoles of product per minute per milligram of total bacterial protein, were measured when the cultures reached the mid-log phase. The substrates employed were aldobiouronic acid (2 mM) to measure α-glucuronidase activity and 4-methylumbelliferyl-β-glucuronide (1 mM) to measure β-glucuronidase activity, as described elsewhere (7).

^cα-Glucuronidase activity was determined in cultures of wild-type P. cellulosa.

^dβ-Glucuronidase activity was determined in cultures of P. cellulosa harboring pTN5.

^eND, no activity detected. The sensitivities of the assays were such that 100 pmol of product/min/mg of protein could be detected with the α-glucuronidase assay and 1 pmol of product/min/mg protein could be detect with the β-glucuronidase assay.