Molec. gen. Genet. 137, 181--183 (1975) © by Springer-Verlag 1975

Short Communication

Lysogeny of Blue-green Alga Plectonema boryanum by Long Tailed Virus

P. K. Singh

Central Rice Research Institute, Cuttack-6, Orissa, India

Received January 28, 1975

Summary. Lysogeny and its induction with mitomycin C by the long tailed virus is reported. The active virus was liberated in the medium during the growth period and ability of trichomes to produce virus was not reduced by treatment with EDTA.

There are only few reports on lysogeny in blue-green algae. Cannon et al. (1971) and Cannon and Shane (1972) established lysogen by the short tailed viruses LPF-D and LPP-2 after t reatment with chloramphenicol where as Padan et al. (1972) could get by LPP-2-SP1 cyanophage. Singh and Singh (1972) reported lysogeny by turbid plaque forming isolate P-2 in P. boryanum and by AR-1 in Anabaenopsis raciborskii. In the present report, lysogeny and its induction with mitomycin C with a long tailed virus (Singh, 1974) in Plectonema boryanum strain 594 of I. U. C. C. is described.

The growth of alga P. boryanum after confluent lysis with long tailed virus appeared rapidly on agar medium as well as in liquid culture and frequency of lysogeny along with virus resistance (MI 10 -3) was 1.8 × 10 -7. Five colonies were isolated and purified by subsequent plating and reisolating. Two of them were virus resistant because they did not produce virus in cultures in subsequent transfers. However, three clones showed the presence of virus in their cultures in repeated transfers, thus had the property of lysogeny. Growth of lysogenie and virus resistant clones was similar to the parent alga. The spontaneous liberation of virus was followed at interval of two days along with growth experiment where titre has increased with the growth of lysogenie clones and decreased at latter phase of their growth (Fig. 1). The growth pat tern was not affected in liquid culture of lysogenic and virus resistent clones in presence of virus. Plaques were also not observed in lawn of these clones due to the virus, which showed immunity of lysogenic clones.

The lysogenic clones were treated with 0.01M of EDTA (pl-I 7.3) for 1 hour which completely inactivated free virus and these were multiplied and tested further for plaques. The titre of virus was more than 10 ~ per ml in supernatant of these cultures. The plaques were produced around the lysogenic filaments in lawn os sensitive alga and used to appear continuously at different times, confirmed that virus is produced during the growth period of lysogenic filaments.

Mitomycin C induction experiments was performed with the exponentially growing cultures (39 Klet t units using red filter) of two of the lysogenie clones and one virus resistant clone with 1 ~xg/ml. The titre of virus at 0 hour served as control

182 P.K. Singh

lO ~

10 3

S

"~ 10 O

g ~- 101[

0 2 z, 6 8 I0 12 Time (days)

Fig. 1. Assay of supernatant fluid of lysogenie and non lysogenic Plectonema boryanum culture. Lysogenic clone-l, o; Lysogenic clone-3, .; Virus resistant clone-l, +

E

g g

(

ld'

2 0 Time (hours)

"Fig. 2. Mitomycin C induction of lysogenie and non lysogenic Plectonema boryanum. Lysogenic clone-l, o; Lysogenic clone-3, .; Virus resistant clone-l, +

in all the t reatments . The induct ion was evident in 2 hours of t r ea tment where sharp increase in t i tre of virus was observed, it continued to increase up to 4 hours and decreasing t rend was noticed at 6 hours (Fig. 2). The virus was absent in all the concentrat ions in culture of virus resistant clone(Fig. 2). There was no increase

Lysogeny of Blue-green Alga Plectonema boryanum 183

in t i t re of v i rus in cul tures of un t r ea t ed lysogenic clones wi th mi tomyc in C in 6 hours. The r ap id rise of virus t i t re af ter 2 hours of mi tomyc in C t r e a t m e n t migh t be due to shor t l a t en t per iod of virus unl ike the observa t ions of Cannon and Shane (1972) where r a p i d rise was not iced in 6 hours. The induc t ion of lysogeny with mi tomyc in C has been r epor t ed (Cannon et al., 1971; Cannon and Shane, 1972; Singh and Singh, 1972), bu t P a d a n et al. (1972) d id no t ge t induct ion wi th it.

The above observa t ions have conf i rmed lysogeny in the alga due to this new virus like bac ter ia l lysogeny.

Acknowledgements. My thanks are due to Director Dr. S.Y. Padmanabhan and Dr. S. Patnaik, Head of Crops & Soils Division for providing laboratory facilities and encouragement.

I gratefully acknowledge Prof. R. ttaselkorn of Chicago University, Illinois, U.S.A. for providing mitomycin C and valuable suggestions.

References Cannon, R. E., Shane, M. S. : The effect of antibiotic stress on protein synthesis in the establish-

ment of lysogeny of PlecSonema boryanum. Virology 49, 130-133 (1972) Cannon, R. E., Shane, M. S., Bush, V. N. : Lysogeny of a blue-green alga, Plectonema boryanum.

Virology 45, 149-153 (1971) Padan, E., Shilo, M., Oppenheim, A. B. : Lysogeny of the blue-green alga Plectonema boryanum

by LPP-2-SP1 eyanophage. Virology 47, 525-526 (1972) Singh, P . K . : Isolation and characterization of a new virus infecting the blue-green alga

Plectonema boryanum. Virology 58, 586-588 (1974) Singh, t~. N., Singh, P. K. : Transduction and lysogeny in blue-green algae. In: Taxonomy and

biology of blue-green algae (ed. T.V. Desikachary), p. 258-261. University of Madras, India 1972

Communica ted b y D. Goldfarb

Dr. P. K. Singh, Algologist Laboratory of Blue-green Algae Central Rice Research Institute, Cuttack-753 006, Orissa, India