Growth dynamic on a co-cultivation of two Chlorophyta microalgae exposed to copper

Aim Copper is an essential nutrient for the phytoplankton, but it can also act as a toxic agent, depending on its concentration. Considering the continuous increase of this metal in the natural aquatic ecosystems, understanding its actions in co-cultivation scenarios is of great relevance. Experiments with the combination of different species resemble more accurately the natural conditions, in contrast of results obtained in single-species tests, which cannot be directly used to describe observed effects on the environment. Methods Therefore, growth parameters were investigated and compared on the co-cultivation of Chlorella sorokiniana and Kirchneriella obesa and their separate cultures exposed to three different free copper concentrations (control 6x10-9, intermediate 2x10-7 and high 1.5x10-6 mol.L-1 Cu2+). Results C. sorokiniana registered more cells in the control of the unialgal culture while K. obesa had higher cell density in the control of the co-cultivation. Growth rates decreased with the increment of copper in the unialgal conditions. However, both species maintained a high growth rate in the co-cultivation intermediate copper concentrations. Biovolume varied despite the cultivation method, being strongly related to the metal’s concentration. The maximum photosynthetic efficiency decreased in higher copper. Conclusions According to the results observed, no competitive exclusion occurred and both species were affected by copper in unialgal and co-cultivation conditions, with K. obesa being favored by the co-cultivation, which seems to have an attenuation effect on copper toxicity until intermediate concentrations. Ecologically, the results suggest that communities deal better with the toxic effects caused by intermediate copper concentrations than single-species cultures.

Draft Genome Sequence of the Cadmium-Resistant Strain JJU2, Belonging to the Family Hapalosiphonaceae of the Cyanobacteria

Here, we report the genome of strain JJU2, a cyanobacterium of the family Hapalosiphonaceae known to be resistant to high cadmium levels, assembled from a nonaxenic, unialgal culture from Marinduque, Philippines. The draft genome is 7.1 Mb long with a GC content of 40.05% and contains 5,625 protein-coding genes.

Histopathological Evaluation of the Exposure by Cyanobacteria Cultive Containing [d-Leu1]Microcystin-LR on Lithobates catesbeianus Tadpoles

This study evaluated the effects of [d-Leu1]Microcystin-LR variant by the exposure of Lithobates catesbeianus tadpole to unialgal culture Microcystis aeruginosa NPLJ-4 strain. The Tadpole was placed in aquariums and exposed to Microcystis aeruginosa culture or disrupted cells. For 16 days, 5 individuals were removed every 2 days, and tissue samples of liver, skeletal muscle, and intestinal tract were collected for histopathology and bioaccumulation analyses. After exposure, those surviving tadpoles were placed in clean water for 15 days to evaluate their recovery. A control without algae and toxins was maintained in the same conditions and exhibited normal histology and no tissue damage. In exposed tadpoles, samples were characterized by serious damages that similarly affected the different organs, such as loss of adhesion between cells, nucleus fragmentation, necrosis, and hemorrhage. Samples showed signs of recovery but severe damages were still observed. Neither HPLC-PDA nor mass spectrometry analysis showed any evidence of free Microcystins bioaccumulation.

Competition and Synergy BetweenProchlorococcusandSynechococcusUnder Ocean Acidification Conditions

ABSTRACTAnthropogenic CO2emissions are projected to lower the pH of the open ocean by 0.2 to 0.3 units over the next century. Laboratory experiments show that different phytoplankton taxa exhibit a wide variety of responses, with some strains having higher fitness under projected future conditions, and others being negatively impacted. Previous studies have suggested thatProchlorococcusandSynechococcus, the numerically dominant picophytoplankton in the oceans, have very different responses to elevated CO2that may result in a dramatic shift in their relative abundances in future oceans. Here we show that these two genera experience faster exponential growth rates under future CO2conditions, similar to most other cyanobacteria that have been studied. However,Prochlorococcusstrains have significantly lower realized growth rates due to more extreme lag periods after exposure to fresh culture media. Surprisingly, however,Synechococcuswas unable to outcompeteProchlorococcusin co-culture at elevated CO2. Under these conditions,Prochlorococcus’ poor response to elevated CO2disappeared, and it showed negative frequency dependence in its relative fitness compared toSynechococcus, with a significant fitness advantage when it was initially rare. Moreover, bothSynechococcusandProchlorococcushad faster growth rates in co-culture with each other than either had in unialgal culture. We speculate that this negative frequency dependence is an outgrowth of reductive Black Queen evolution operating on both taxa that has resulted in a passively mutualistic relationship analogous to that connectingProchlorococcuswith the “helper” heterotrophic microbes in its environment.

Draft Genome Sequence of a Tropical Freshwater Cyanobacterium, Limnothrix sp. Strain P13C2

A nonaxenic unialgal culture of Limnothrix sp. strain P13C2 was obtained through multiple subculturing of an inoculum obtained from a tropical freshwater lake. Here, we report the genome of P13C2 of 4.6 Mbp, extracted from the metagenome of this coculture.

Draft Genome Sequence of Cylindrospermopsis sp. Strain CR12 Extracted from the Minimetagenome of a Nonaxenic Unialgal Culture from a Tropical Freshwater Lake

Cylindrospermopsis is known to be one of the major bloom-forming cyanobacterial genera in many freshwater environments. We report here the draft genome sequence of a tropical Cylindrospermopsis sp. strain, CR12, which is capable of producing the hepatotoxic cylindrospermopsin.

Isolation, Screening and Optimization of Estuary Region (Khambhat, Gujarat) Microalgae for Lipid/Oil Production

Water and soil samples were collected from gulf of Khambhat region, Gujarat. The cations and anions like calcium, chloride, fluoride, magnesium, sulphate and total hardness as calcium carbonate were analyzed. Collected estuarine samples were cultured in three different media under standard laboratory conditions. These enrichments were then used to isolate pure unialgal culture by conventional method. Thirty four isolates belonging to twelve species of Cyanobacteria, twenty species of Chlorophyta and two taxa of Bacillariophyta were identified and are maintained at SPRERI centre. The Chlorophyta were found better accumulators of lipids than the cyanobacterial species. Five promising strains (SBC 7, SBC 9, SBC 17, SBC 18 and SBC 19) have been selected. In-house isolates SBC19 and SBC 17 showed highest acetyl CoA carboxylase (ACCase) of 55.2 (U/ml) and 51.2 (U/ml) respectively, with 0.375 g l-1 nitrogen concentration in 24 days. Biomass production was highest for 2.4 g/l, (SBC 19) and 2.7 g/l (SBC 17) with 1.5 g l-1 nitrogen concentration. The highest lipid content was 52% and 48% in SBC19 and SBC 17, respectively, with 0.375 g l-1 nitrogen concentration of solvent extraction method. Lipid accumulation was found enhanced by more than 50% on dry mass basis under nitrogen starvation.Int J Appl Sci Biotechnol, Vol 3(2): 197-201 DOI: http://dx.doi.org/10.3126/ijasbt.v3i2.12534

Effects of pH on cell morphology and carbonic anhydrase activity and localization in bloom-forming Mougeotia (Chlorophyta, Charophyceae)

A species of Mougeotia (C.A. Agardh) that was the dominant component of a metaphytic bloom-forming filamentous algal assemblage in an experimentally acidified lake (Little Rock Lake, Vilas County, Wisconsin, U.S.A.) was isolated into unialgal culture for analysis of pH effects on cell morphology and carbonic anhydrase activity and localization. External and total carbonic anhydrase activities at pH 8 were significantly greater than those at pH 5, but internal carbonic anhydrase activities were not significantly different at the two pH levels, as determined by use of a potentiometric technique. Ultrastructural immunogold labeling with a polyclonal antibody to Chlamydomonas periplasmic carbonic anhydrase suggested that an antigenically similar protein was located in the periplasmic space, inflated end walls, chloroplast, and peripheral cytoplasm of Mougeotia grown at both pH 8 and 5. Activity measurements and localization data were consistent with the hypothesis that a carbon concentration mechanism operates in this Mougeotia species at both high and low pH. Growth form, cell dimensions, chloroplast morphology, and cell wall ultrastructure were significantly different in cultures grown at pH 5 and pH 8. These structural and carbon acquisition features may contribute to Mougeotia's ability to form conspicuous metaphytic blooms in acidified waters.Key words: carbonic anhydrase, acidification, algal blooms, Mougeotia.

A Rapid Bioassay for Selective Algicides

Cyanobacteria (blue-green algae) are undesirable in ponds used to raise fish for human food. Management of cyanobacterial communities in aquaculture ponds has been hindered by the small number of herbicides approved for use in food-fish ponds and by the lack of selectivity toward cyanobacteria for those herbicides that are approved for that use. To facilitate development of additional management options, a rapid bioassay utilizing 96-well cell culture plates was developed for screening herbicides and other phytotoxins for selective toxicity toward cyanobacteria.Oscillatoriacf.chalybeaandSelenastrum capricornutumwere chosen as representatives of cyanobacteria (Cyanophyta) and green algae (Chlorophyta), respectively. In the bioassay, wells of the cell culture plates were inoculated with cyanobacterial or unialgal culture. One of five herbicides (atrazine, diuron, endothall, fluridone, or paraquat) was then added to the wells at various concentrations, and absorbance (650 nm) was measured at 24-h intervals. Growth of treated cultures relative to untreated cultures was used to determine relative toxicity of the herbicide to the two organisms. Paraquat was the most selective of the herbicides tested and was over 10-fold more toxic toO.cf.chalybeathan toS. capricornutum. This method was demonstrated to be a rapid, effective, and highly reproducible bioassay to identify selective algicides.

Toxicity tests in eight species of Chrysochromulina (Haptophyta)

Blooms of the marine flagellate Chrysochromulina have resulted in mortality of marine organisms in Scandinavian waters, including fish in aquaculture. Eight species of Chrysochromulina, namely C. apheles, C. brevifilum, C. ericina, C. hirta, C. leadbeateri, C. parva, C. polylepis, and C. simplex, isolated into unialgal culture, were examined for haemolytic activity and toxicity to the brine shrimp, Artemia salina. Haemolytic fractions were obtained from all species, but only C. polylepis cells were toxic to Artemia. Thin-layer chromatography (TLC) analysis in chloroform –methanol–water (75:25:4) and in chloroform–methanol (9:1) yielded up to six haemolytic spots. Except for one spot, these all occurred in extracts of the species examined, including Isochrysis sp., which was used as a control, C. polylepis, and the well-known fish killer Prymnesium parvum. The single unique haemolytic spot (Rf values 0.45 and 0.16 in solvents I and II, respectively) occurred in the extract from C. polylepis. When isolated by TLC, the contents of the single spot were toxic to Artemia. Key words: Chrysochromulina, toxicity, haemolytic, Artemia, thin-layer chromatography (TLC).