FIG 4.

Visualization of the C. japonicus gsp cellulase secretion defect via Congo red staining. Representative spot test for cellulase secretion shown for 10 Δgsp mutants taken from selection 1A. A diminished zone of clearance compared to that of the wild type (WT) identified secretion-deficient mutants. The gspD KO strain was used as a known secretion-deficient control. This plate shows four Δgsp secretion-deficient mutants (1, 2, 5, and 8). Subsequent PCR screening indicated that these four putative mutants had the entire gsp operon deleted.