Enhancement of ascomycin production via a combination of atmospheric and room temperature plasma mutagenesis in Streptomyces hygroscopicus and medium optimization

AMB Express

Table 4 Ascomycin production by different S. hygroscopicus strains

Strains (S. hygroscopicus)	Methods	Scale	Ascomycin (mg/L)	References
FS35	Titanium sapphire laser system^a	1 L flask	305.6	Qi et al. (2012)
SA68	Titanium sapphire laser system and shikimic acid enduring screening model^b	1 L flask	450.0	Qi et al. (2014)
HA-Hcd-Ccr	Overexpression of hcd and ccr^c	1 L flask	438.9	Wang et al. (2017)
OfkbRE	Overexpression of fkbR1 and fkbE^d	1 L flask	536.7	Song et al. (2017)
TD-ΔPyc-FkbO	Overexpressing fkbO and inactivating Pyc^e	3 L fermenter	610.0	Qi et al. (2017)
SFK-36	ARTP mutagenesis and medium optimization	5 L fermenter	1476.9	This study

^aThe FS35 mutant strain was obtained in the optimal irradiation conditions (25 mW for 6 min) by the Titanium sapphire laser system (810 nm, 76 MHz, 150 fs)
^bTitanium sapphire laser system (25 mW for 6 min) was combined with an enduring selection mode containing 5 g/L shikimic acid to generate SA68 mutant strain
^cFunctional gene hcd and ccr were overexpressed together under the control of promoter PermE* and integrated into ΦC31 integration site of FS35 strain to generate engineering strain HA-Hcd-Ccr
^dPositive regulatory gene fkbR1 and functional gene fkbE were overexpressed together under the control of PermE* and integrated into ΦC31 integration site of FS35 strain
^eGene deletion plasmid pΔPyc derived from pKC1139 was used for inactivating Pyc gene in SA68 strain to generate engineering strain TD-ΔPyc. And then, fkbO gene under the control of PermE* was integrated into ΦC31 integration site of strain TD-ΔPyc through conjugal transfer