Through the work of Korolev, his colleagues and students, the microbiology of milk and dairy products was developed considerably.

In 1902, for participation in the revolutionary movement Sergey Korolev was sent to the Arkhangelsk province, but since 1907 received permission to live in Moscow, worked for agronomists bacteriological station.

At 1918, Sergei Alexandrovich Korolev worked at the Department of Microbiology and Zoology at the Vologda Milk Institute.

Inihovym and students studied the microbiological and biochemical processes of maturation of a number of hard and soft cheese, produced in the USSR.

The work enabled the first time to make a harmonious synthesis of a unified theory of ripening cheeses.