| 单词 | lac− |
| 释义 | > as lemmaslac− 1. In lac−: designating a bacterium that lacks the ability to metabolize lactose, and the condition of being unable to metabolize lactose; = lactose-negative adj. at lactose n. Compounds. In lac+: = lactose-positive adj. at lactose n. Compounds. ΘΚΠ the world > life > biology > organism > micro-organism > bacterium > [adjective] > specific quality of tetragenous1888 lysogenic1899 toxicogenic1899 cryophilic1916 R1920 rough1921 smooth1921 sulphate-reducing1926 thermoduric1927 lac−1947 induced1951 inducible1953 thermoacidophilic1976 1947 J. Lederberg in Genetics 32 505 Particular attention was paid to the isolation of ‘lactose-negative’ or ‘Lac−’ mutants [of E. coli]. 1952 Nature 24 May 882/2 The number of papillæ forming on surface colonies of lac− bacteria, grown on agar containing lactose and another carbon source, is a reflexion of the number of mutations to the lac+ condition. 1963 Proc. National Acad. Sci. U.S.A. 50 1052 The majority of the chromosomal recombinants tested were lac+. 1991 New Scientist 21 Sept. 33/1 While lac− bacteria need a carbon source other than lactose, lac+ bacteria are content to grow on lactose. 2007 Environmental Health Perspectives 115 1268/2 In Escherichia coli, starvation of lac− bacteria on lactose medium induces lac+ revertants. < as lemmas |
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