Abstract: A mutant strain of Micromonospora purpurea herein designated M. purpurea JI-20 elaborates an antibiotic complex comprising gentamicin and at least two novel antibiotic substances namely Antibiotic JI-20A and Antibiotic JI-20B. The so-produced antibiotics have an adverse effect upon the growth of gram-positive and gram-negative bacteria.

Abstract: In a process for the purification of an organically contaminated liquid in an aeration tank in the presence of activated sludge, wherein a gas having a higher concentration of oxygen than air is introduced into an aeration tank, containing a mixture of liquid and activated sludge said tank having above at least the major part of the liquid, an atmosphere more enriched with oxygen than air, wherein said liquid and activated sludge are passed to a secondary settling tank and wherein a portion of the activated sludge obtained from the secondary settling tank is recycled as return sludge into the aeration tank,The improvement which comprises:Subjecting at least a portion of said mixture or a recycle stream thereof to a stripping step with a gas to strip out CO.sub.2 from said liquid and prevent a buildup of CO.sub.2 in said aeration which would otherwise lower the efficiency of the purification process.