Abstract: A novel biphenyl derivative of the formula: ##STR1## wherein Ring A is a substituted or unsubstituted sulfur-containing or oxygen-containing heteromonocyclic ring; Ring B is a ring of the formula: ##STR2## each of R.sup.1 and R.sup.3 is hydrogen atom, a halogen atom or a lower alkoxy group, or R.sup.1 is hydrogen atom, and R.sup.2 and R.sub.3 are combined together to form a lower alkylenedioxy group; R.sup.4 is a lower alkyl group which may have a substituent selected from a lower alkoxy group and a lower alkoxycarbonyl group; Y is methylene group or carbonyl group, and a pharmaceutically acceptable salt thereof are disclosed. Said derivative and a pharmaceutically acceptable salt thereof are useful as a therapeutic or prophylactic agent for hepatic diseases.

Abstract: A method for the fermentative production of L-proline which comprises cultivating a L-proline-producing mutant of a microorganism belonging to the genus Serratia in a broth to produce and accumulate L-proline therein and collecting accumulated L-proline. The mutant is preferably that of Serratia marcescens which is deficient in L-proline oxidase and is resistant to proline analong under a high osmotic pressure.