Table 5.

Characterization of the CRISPR loci of S. islandicus REY15A (family I) after challenging with constructs carrying protospacers matching spacers within locus 1 and/or 2 (Fig. 2).

			CRISPR locus deletion
Experiment	CRISPR locus/spacer (+CC motif)	Transformation efficiency [cfu (µg DNA)−1]	PCR estimate (kb)	Sequencing result
1	L2/45 + L1/20	4	> 17 kb (3×)	L1 + L2 (×2)
2	L1/1	6	64 bp (2×)	r1–r2 (×2)
			0.2 and 5	Leader–r3 and r1–r80

Each construct was tested twice and transformation efficiencies were averaged. L1 + L2 indicates that both CRISPR loci are deleted, and r1–r2 shows that recombination had occurred between repeats 1 and 2 with the resultant deletion of spacer 1 and one repeat.