Heterologous expression in Saccharopolyspora erythraea of a pentaketide synthase derived from the spinosyn polyketide synthaseElectronic supplementary information (ESI) available: Further details of the construction of pCJR308, the fermentation of BIOT-0966 and the isolation of pentaketide lactone, 3, and figures showing the13C NMR and 1H COSY spectra of 3. See http://www.rsc.org/suppdata/ob/b3/b310740j/