Table 1. Primers and Conditions for the Two-Tiered PCR Method to Prepare a Pool of Pathway-Specific Probes and Use Them to Survey Strains for Biosynthetic Potential of the Targeted Class of Natural Products.

natural product class	pathway-specific probe	primera	1st round PCR	2nd round PCR	hybridization temp (°C)
reduced polyketides	type I PKS	5′-ATGTAGTGAGCTGCTTCGGCGATGGACCCGCAGCAGCG-3′	95 °C/30 s; 60 °C/1 min; 72 °C/40 s; 10 cycles	95 °C/30 s; 48 °C/30 s; 72 °C/40 s; 35 cycles	55
		5′-AATCAGCATCCTTCGACCGCGCCGTCCTGGTTSACSGC-3′
aromatic polyketides	type II PKS	5′-ATGTAGTGAGCTGCTTCGGGCAGCGGITTCGGCGGITTCCAG-3′	95 °C/30 s; 65 °C/1 min; 72 °C/30 s; 10 cycles	95 °C/30 s; 48 °C/30 s; 72 °C/30 s; 35 cycles	55
		5′-AATCAGCATCCTTCGACCCGITGTTIACIGCGTAGAACCAGGCG-3′
nonribosomal peptides	NRPS	5′-ATGTAGTGAGCTGCTTCGACCTCSGGCWCCACCGGC-3′	95 °C/30 s; 65 °C/1 min; 72 °C/50 s; 10 cycles	95 °C/30 s; 48 °C/30 s; 72 °C/50 s; 35 cycles	57
		5′-AATCAGCATCCTTCGACCGCCGSIGATCTTSACCTG-3′
diterpenoids	DTS	5′-ATGTAGTGAGCTGCTTCGACGCTCAGTGCGGTSGAG-3′	95 °C/30 s; 65 °C/1 min; 72 °C/1 min; 10 cycles	95 °C/30 s; 48 °C/30 s; 72 °C/1 min; 35 cycles	58
		5′-AATCAGCATCCTTCGACCGGIGAGGCGTGCCACTTGTC-3′

^aThe designer primers consisted of the pathway-specific sequences and the unbiased AT-rich tag (underlined). S, C/G; W, A/T; I, inosine.