Isolation and preliminary characterization of auxotrophs of a filamentous cyanobacterium

Journal Article · Tue Mar 01 04:00:00 EST 1977 · J. Bacteriol.; (United States)

OSTI ID:7323949

Currier, T C; Haury, J F; Wolk, C P

Auxotrophic mutants of the filamentous cyanobacterium Anabaena variabilis were isolated by a method in which, after mutagenesis and before penicillin enrichment, mutant and wild-type cells were separated by cavitation. Auxotrophs were identified by their inability to grow on minimal medium, and they were partially characterized by replica plating to media supplemented with single nutrients or specific groups of nutrients. Of the 83 auxotrophs isolated, 65 required an inorganic source of nitrogen for growth. In addition, auxotrophs were isolated that required methionine (six), uracil (two), adenine (one), biotin (two), and nicotinic acid (two). (The number of isolates of each type is indicated in parentheses.) The nutrient requirements of five auxotrophs appeared complex and were not determined. A large proportion of the mutants that required inorganic fixed nitrogen was altered in the differentiation of heterocysts. The following morphological aberrancies were observed: abnormally high and abnormally low frequencies of heterocysts; thick, uneven heterocyst envelopes; incompletely developed pore regions; very distinct pore regions; and protoplasts separated from the envelope of the heterocyst. Spontaneously occurring, N/sub 2/-fixing, prototrophic revertants of mutants with aberrant heterocysts have been isolated at a frequency of 2 x 10/sup -8/ to 4 x 10/sup -8/ of the cells plated. That most such revertants produced morphologically normal heterocysts is consistent with the idea that heterocysts play an essential role in aerobic N/sub 2/ fixation.

• Research Organization: Michigan State Univ., East Lansing
• OSTI ID: 7323949
• Journal Information: J. Bacteriol.; (United States), Journal Name: J. Bacteriol.; (United States) Vol. 129:3; ISSN JOBAA
• Country of Publication: United States
• Language: English

Related Subjects

550701* -- Microbiology-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
BACTERIA
MICROORGANISMS
MUTANTS
NITROGEN FIXATION
NUTRIENTS