Growth measurements by monitoring light scattering of a filamentous blue-green alga which does not give uniform and stable suspension in culture vessels
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Cited by 6 publications
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Ultraviolet sensitivity of two different species of Anabaena, Anabaena doliolum and Anabaena sp. was studied. These two species differ in their pigment composition; A . doliolum showed predominance of phycocyanin whereas Anabaena sp. showed predominance of phycoerythrin pigments. Survival of the two species were different after exposure to different doses of UV (A,,, 254 nm) irradiation; Anabaena sp. was more resistant to higher UV dose than A . doliolum. In both species the UV induced damage was partially repaired by white fluorescent light. A . doliolum showed a lower rate of photorecovery than Anabaena sp.. Higher UV dose (20 min) induced production of a non-nitrogen fixing strain of A. doliolum and a pigment mutant lacking phycoerythrin of Anabaena sp.Ultraviolet-induced damage and photoreactivation studies on cyanobacteria was pioneered by VAN BAALEN (1965. Since then several reports appeared on the UV sensitivity, dose modification and photoreactivation of a variety of cyanobacteria (KUMAR 1970, KASHYAP 1978, SINGH 1978. Characteristics of ultraviolet resistant and wild type strains of various cyanobacteria have been compared (KUMAR 1963, SINGH and TIWARI 1969, MISHRA and TIWARI 1986. Pigment mutants induced by UV ( VAN BAALEN 1965, MISHRA and TIWARI 1989), nitromethyl urea (SHESTAKOV and ZHENVER 1968 and N-methyl-NNitro-N-nitroso guanidine (ASATO and FOLSOME 1969) have been observed in a few species of cyanobacteria, but have not been widely investigated (STEVANS and MYERS 1976). The present work deals with the survival of two species of Anabaena after irradiation with various doses of UV. The generation of different type of mutants in different species of Anabaena by high UV dose was observed. Materials and methodsTwo different species of the filamentous nitrogen-fixing cyanobacterium Anabaena, (i) bluish green Anabaena doliolum, isolated from local rice fields (TRIPATHY et al. 1990) and (ii) brownish Anabaena sp. isolated from a distillery effluent polluted area (SAHU and ADHIKARY 1982) were used as the experimental material. The organisms were grown in the culture room in ALLEN and ARNON'S nitrogen free medium (1955) at 26 f 1 "C under continuous light (7.5 W/m2 at the surface of culture vessels) from daylight fluorescent tubes. The cells of both the organisms growing exponentially in the basal medium were concentrated and washed by repeated centrifugation with sterilized double distilled water. The cells were suspended in the same and brought into homogeneous suspension by a glass tissue homogenizer. 15 ml of this suspension (density = 0.05 absorbance at 760 nm) was poured into a 75 mm petridish. The suspension was then exposed to UV radiation under a general Electric germicidal lamp (American Ultraviolet Co., USA) emitting in the wavelength range of 325-375 nm with its main output at 254 nm and the radiation dose of about 85 ergs mm-' s-' at a distance of 22 cm. During irradiation with UV in the absence of white light, the suspension was constantly stirred by a magnetic 428 J. PATNAIK et al.stirrer an...
Ultraviolet sensitivity of two different species of Anabaena, Anabaena doliolum and Anabaena sp. was studied. These two species differ in their pigment composition; A . doliolum showed predominance of phycocyanin whereas Anabaena sp. showed predominance of phycoerythrin pigments. Survival of the two species were different after exposure to different doses of UV (A,,, 254 nm) irradiation; Anabaena sp. was more resistant to higher UV dose than A . doliolum. In both species the UV induced damage was partially repaired by white fluorescent light. A . doliolum showed a lower rate of photorecovery than Anabaena sp.. Higher UV dose (20 min) induced production of a non-nitrogen fixing strain of A. doliolum and a pigment mutant lacking phycoerythrin of Anabaena sp.Ultraviolet-induced damage and photoreactivation studies on cyanobacteria was pioneered by VAN BAALEN (1965. Since then several reports appeared on the UV sensitivity, dose modification and photoreactivation of a variety of cyanobacteria (KUMAR 1970, KASHYAP 1978, SINGH 1978. Characteristics of ultraviolet resistant and wild type strains of various cyanobacteria have been compared (KUMAR 1963, SINGH and TIWARI 1969, MISHRA and TIWARI 1986. Pigment mutants induced by UV ( VAN BAALEN 1965, MISHRA and TIWARI 1989), nitromethyl urea (SHESTAKOV and ZHENVER 1968 and N-methyl-NNitro-N-nitroso guanidine (ASATO and FOLSOME 1969) have been observed in a few species of cyanobacteria, but have not been widely investigated (STEVANS and MYERS 1976). The present work deals with the survival of two species of Anabaena after irradiation with various doses of UV. The generation of different type of mutants in different species of Anabaena by high UV dose was observed. Materials and methodsTwo different species of the filamentous nitrogen-fixing cyanobacterium Anabaena, (i) bluish green Anabaena doliolum, isolated from local rice fields (TRIPATHY et al. 1990) and (ii) brownish Anabaena sp. isolated from a distillery effluent polluted area (SAHU and ADHIKARY 1982) were used as the experimental material. The organisms were grown in the culture room in ALLEN and ARNON'S nitrogen free medium (1955) at 26 f 1 "C under continuous light (7.5 W/m2 at the surface of culture vessels) from daylight fluorescent tubes. The cells of both the organisms growing exponentially in the basal medium were concentrated and washed by repeated centrifugation with sterilized double distilled water. The cells were suspended in the same and brought into homogeneous suspension by a glass tissue homogenizer. 15 ml of this suspension (density = 0.05 absorbance at 760 nm) was poured into a 75 mm petridish. The suspension was then exposed to UV radiation under a general Electric germicidal lamp (American Ultraviolet Co., USA) emitting in the wavelength range of 325-375 nm with its main output at 254 nm and the radiation dose of about 85 ergs mm-' s-' at a distance of 22 cm. During irradiation with UV in the absence of white light, the suspension was constantly stirred by a magnetic 428 J. PATNAIK et al.stirrer an...
A phycoerythrin‐lacking mutant induced by DCMU in photoheterotrophically grown Nostoc linckia
A blue-green strain showing loss of phycoeryhtrin pigment was obtained from the 15 nm fructose and lo-* M DCMU [3-(3,4-dichlorophenyl), 1,l-dimethyl urea] supplemented photoheterotrophic culture of the blackish-brown rice-field cyanobacterium Nostoc linckiu. Absence of phycoerythrin in the mutant strain was ascertained from the whole cell absorption spectra and spectra of water soluble pigments. Quantitative estimation of photosynthetic pigments of the parent and mutant strain showed that increase in the chlorophyll and phycocyanin content took place in the mutant with a total loss of phycoerythrin.Subculturing under low and high light intensities brought no change in the mutant. The mutant strain grew well, synthesized high amounts of chlorophyll and phycocyanin and possessed higher nitrogen-fixing capacity in comparison to the parent material. Various types of mutants have been isolated by using known chemical mutagens like NTG(N-methyl-N'-nitro-N-nitrosoguanidine), EMS (ethyl methane sulphonate) and other toxic chemicals (MISHRA and TIWARI 1986, KHAN and GODWARD 1977, TRIPATHY and KUMAR 1986, ASTIER et al. 1979). However, pigment mutants have only been occasionally observed and isolated and never widely worked out. Usually pigment mutants of cyanobacteria are altered in content of one or more of the pigments, chlorophyll (MYERS et al. 1978), phycocyanin (STEVENS and MYERS 1976, SHAFFER et al. 1978), phycoerythrin (BEGUIN et al. 1985, MISHRA andTIWARI 1989) or carotenoids (LADHA and KUMAR 1978). A DCMU induced phycoerythrin loss mutant of a blackish-brown coloured rice-field cyanobacterium Nostoc linckia has been isolated from its photoheterotrophic culture. This paper presents data on pigment composition of the DCMU induced phycoerythrin lacking mutant and compares it with that of the autotrophically grown Nostoc linckia. Materials and methodsThe cyanobacteriumtfostoc linckiu (ROTH) BORN. et FLAH. was isolated from local rice-fields during Rabi crop season, 1988 and clonal culture was raised from a single filament. It looks blackish-green to brownish in colour and grows attached to rice plants (TRIPATHY et al. 1992). The cyanobacterium was grown in axenic culture in nitrogen free BGll medium at 26 f 1 "C temperature under continuous light at an intensity of 7.5 W/m2 provided from day light fluorescent tubes. Cultures were maintained in agar tubes (1 % w/v DFCO nutrient agar) and transferred to liquid medium before they were used in the experiments.Growth experiments were performed in hard glass test tubes ( 1 5~ 150 mm) containing 10 ml of culture medium and aliquots of homogeneous suspension of the organism (absorbance of the culture suspension at 760 nm = 0.2) as inocula. Heterotrophic growth of Nostoc linckiu was studied in presence of fructose (15 m) in the culture medium. For photoheterotrophic growth studies, stock solutions of the herbicide DCMU was prepared and an aliquot added to the sugar supplemented medium to get a final concentration of M. All aqueous additions to the sterile mineral medium were...
Pesticide contamination in the rice fields has manifested into a serious global environmental concern. Application of pesticides in the rice fields has deleterious effects on non-target organisms including nitrogen-fixing cyanobacteria which help to maintain the rice field fertility. In the present research endeavor, the effect of lambda cyhalothrin (5% EC), a synthetic pyrethroid insecticide, has been studied on the growth and pigments content of Calothrix sp. (GUEco 1001), an indigenous strain isolated from rice grown areas of Brahmaputra floodplain. To study the toxic effect of lambda cyhalothrin, the test organism was exposed to varying concentrations of the insecticide i.e., 20 ppm, 40 ppm, 80 ppm, and 160 ppm based upon the determination of LC50 for a period of 20 days. The result obtained in the laboratory showed a progressive decrease in the growth and pigments content by the test organism with increasing concentrations of the lambda cyhalothrin against time dose-dependent manner. At high dose (160 ppm), the test organism showed significant decrease in dry weight biomass (54.5%), chlorophyll-a (68%), carotenoids (38%), phycocyanin (80%), and nitrogen contents (55%) over the control. A little but insignificant stimulatory effect on growth and chlorophyll-a contents was recorded in 20 ppm treatment of the insecticide that, however, was reversed in case of carotenoids and phycocyanin contents.
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