TABLE 2 

Substrate-specific activities of positive metagenomic clones from the [13C]cellulose DNA-SIP library

CloneInsert size
(kb)
Activity (μM MU released)aCMC
activityb
α-l-Arabinofuranoside
pyranoside
β-d-
Cellobiopyranoside
β-d-
Glucopyranoside
β-d-
Xylopyranoside
N-Acetyl-β-d-
galactosaminide
C12221.60.40.20.60.7124.2
C4248.20.957.6109.41.60.7
C76213.52.45.421.20.70.4
C102416.8123.86.535.81.70.5
C108811.90.525.679.21.20.6
C219412.90.50.30.60.439.6
C238014.90.380.460.530.410.40+++
C204414.70.400.400.520.390.36++
  • a Cellulase activity was scored by Congo red staining of clones on the LB-CMC plate. Other activities were measured in cell-free extracts using methylumbelliferone-based substrates. MU, methylumbelliferone units based on equal volumes of sample for each assay.

  • b CMC, carboxymethyl cellulose. Plate-based clearing (high, +++; medium, ++; negative, −) was detected by Congo red stain and activity based on comparison to those of positive and negative controls.