ISOLATION AND CHARACTERIZATION OF A NOVEL BACTERIUM GROWING VIA REDUCTIVE DEHALOGENATION OF 2-CHLOROPHENOL

A bacterium capable of anaerobic growth via reductive dehalogenation o f 2-chlorophenol was isolated from a culture enriched from sediment ta ken from a small stream near Lansing, Mich. The organism, designated s train 2CP-1, is a gram negative rod ca. 3 by 0.5 mu m in size and is a catalase-negative, oxidase-negative, facultative anaerobe that forms small red colonies in anaerobic media. The organism grew in reduced an aerobic mineral medium supplemented with 2-chlorophenol, acetate, and vitamins, producing phenol as a product. It did not grow when either 2 -chlorophenol or acetate was omitted. The growth yield was about 3 g o f protein per mol of 2-chlorophenol dechlorinated, and the doubling ti me was 3.7 days. Only the ortho position was dehalogenated, and additi onal chlorines at other positions decreased or blocked ortho dechlorin ation. The organism also grew with fumarate as its electron acceptor. Dechlorination activity is inducible, since cultures grown in fumarate containing medium with 2-chlorophenol rapidly dechlorinated additiona l 2-chlorophenol, while cultures grown in the same medium without 2-ch lorophenol did not. Analysis of the organism's 168 rRNA sequence revea led that it is a member of the delta proteobacteria, more closely rela ted to the myxobacteria than to the sulfidogenic bacteria.