nóng jì rén yuán / tōng guò / gēng huàn / péi yǎng jī / bāng zhù / tuì huà / de / jūn zhǒng / fù zhuàng

农技人员通过更换培养基，帮助退化的菌种复壮。

Agricultural technicians helped the degraded strain regain its vitality by replacing the culture medium.