Phormidium Foveolarum Research Articles

Nostoc muscorum and Phormidium foveolarum differentially respond to butachlor and UV-B stress.

Present study deals with responses of two cyanobacteria viz. Nostoc muscorum and Phormidium foveolarum against butachlor [2-chloro-2,6-diethyl-N-(butoxymethyl) acetanilide] (low dose; 5µgmL-1 and high dose; 10µgmL-1) and UV-B (7.2kJm-2) alone, and in combination. Butachlor and UV-B exposure, alone and in combination, suppressed growth of both the cyanobacteria. This was accompanied by inhibitory effect on whole cell oxygen evolution and photosynthetic electron transport activities. Both the stressors induced the oxidative stress as there was significant increase in superoxide radical (O2 ·-) and hydrogen peroxide (H2O2) contents resulting into increased lipid peroxidation and electrolyte leakage. In N. muscorum, low dose of butachlor and UV-B alone increased the activities of superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD), while activity of all these enzymatic antioxidants declined significantly at treatments with high dose of butachlor alone, and with low and high doses of butachlor and UV-B in combination. In P. foveolarum, enhanced activity of SOD, CAT and POD (except POD at high dose of butachlor and UV-B combination) was noticed. Ascorbate level in N. muscorum declined progressively with increasing intensity of stress while in P. foveolarum varied response was noticed. Proline contents increased progressively under tested stress in both the organisms. Overall results suggest that N. muscorum was more sensitive than P. foveolarum against butachlor and UV-B stresses. Hence, P. foveolarum may be preferred in paddy field for sustainable agriculture.

An investigation on involvement of the ascorbate-glutathione cycle in modulating NaCl toxicity in two cyanobacteria photoacclimatized to different photosynthetic active radiation

In the present study, comparative responses of two cyanobacteria viz. Nostoc muscorum and Phormidium foveolarum, photoacclimatized at three distinct levels (sub-optimum; 25±0.5, optimum; 75±2.5 and supra-optimum; 225±3.5μmolphotonsm−2s−1) of photosynthetic active radiation (PAR), and subsequently treated with two doses (30 and 90mM) of NaCl were determined by analyzing changes in growth pattern, oxidative stress markers, enzymes of the ascorbate-glutathione cycle i.e. ascorbate peroxidase (APX), glutathione reductase (GR), monodehydroascorbate reductase (MDHAR) and dehydroascorbate reductase (DHAR), and associated metabolites (ascorbate and glutathione). PAR influences growth behavior of both cyanobacteria, as maximum growth observed in supra-optimum PAR acclimatized cells followed by optimum and sub-optimum PAR. Maximum superoxide radical (SOR) and hydrogen peroxide (H2O2) contents and their consequent damages to lipids in terms of MDA equivalents were observed in supra-optimum PAR acclimatized cells in individual as well as in combined treatment of NaCl. Further, NaCl-induced the least percent reduction in growth was observed in supra-optimum PAR acclimatized cells, which was in consistence with increased activities of the AsA-GSH cycle enzymes (APX, GR, MDHAR and DHAR) and its associated metabolites i.e. ascorbate (AsA) and glutathione (GSH) contents and reduced and oxidized ratios of ascorbate (AsA/GSH) and glutathione (GSH/GSSG). The results suggest that the AsA-GSH cycle might have associated with better growth in supra-optimum PAR acclimatized cells than optimum and sub-optimum PAR acclimatized cells under NaCl stress. Besides this, study also establishes fact that P. foveolarum is more tolerant than N. muscorum against these twin stresses, and may be inoculated in paddy fields under existing environmental conditions for increasing fertility of the soil.

Waste-free technology of wastewater treatment to obtain microalgal biomass for biodiesel production

Five axenic cultures of microalgae were isolated from the wastewater of Almaty city and identified as Chlorella vulgaris strain № 1, Chlorella sp. strain № 3, Scenedesmus obliquus, Phormidium foveolarum and Lyngbya limnetica. Among these strains, C. vulgaris strain № 1 was characterized by the maximum growth rate and the highest productivity. Mass cultivation of this strain in wastewater resulted in accumulation of 5 × 107 cells per ml in 16 days, and in the removal of ∼95% of pollutants from water. Cells of C. vulgaris consisted of ∼35% proteins, 29% carbohydrates, 30% lipids, and 6% ash, as calculated on a dry weight basis. The major fatty-acids of C. vulgaris were represented by palmitic, cis-7,10-hexadecenoic acid, linoleic, and α-linolenic acids. Culturing in wastewater decreased the unsaturation index of FAs. Thus, C. vulgaris cells are suitable for both waste water purification and accumulation of biomass for further biodiesel production.

NaCl-induced physiological and biochemical changes in two cyanobacteria Nostoc muscorum and Phormidium foveolarum acclimatized to different photosynthetically active radiation

The present study is aimed at investigating physiological and biochemical behavior of two cyanobacteria Nostoc muscorum and Phormidium foveolarum acclimatized to different levels (sub-optimum; 25±0.5, optimum; 75±2.5 and supra-optimum; 225±3.5μmolphotonsm−2s−1) of photosynthetic active radiation (PAR), and subsequently treated with two doses (30 and 90mM) of NaCl. PAR influences growth in tested cyanobacteria being maximum in supra-optimum PAR acclimatized cells. NaCl-induced maximum percent decline in growth was observed in sub-optimum PAR acclimatized cells, which was in consonance with a decrease in chlorophyll content. Sub-optimum PAR acclimatization stimulated phycocyanin content in control cells, whereas maximum carotenoids content was observed in supra-optimum PAR acclimatized cells. Photosystem II photochemistry viz. Fv/F0, Fv/Fm, Ψ0, ϕE0, PIABS, ABS/RC, TR0/RC, ET0/RC and DI0/RC was also influenced by PAR and NaCl. Maximum percent rise in superoxide radical (SOR), hydrogen peroxide (H2O2) and lipid peroxidation was observed in sub-optimum PAR acclimatized cells exposed to NaCl, which could be correlated with lower values of enzymatic (superoxide dismutase, catalase, peroxidase and glutathione-S-transferase) and non-enzymatic (NP-SH and cysteine) antioxidants. In supra-optimum PAR acclimatized cells level of oxidative stress markers was in parallel with enhanced antioxidants. The results suggest that PAR significantly changes physiological and biochemical responses of studied cyanobacteria under NaCl stress. Besides this, this study also shows that P. foveolarum is more tolerant than N. muscorum under test conditions.

UV-B induces biomass production and nonenzymatic antioxidant compounds in three cyanobacteria

In the present study, the impact of low fluence rate of UV-B (0.045 W.m−2) on biomass production, photosynthetic pigments (chlorophyll a, carotenoids, and phycobiliproteins), chlorophyll fluorescence, nonenzymatic antioxidants: proline, ascorbate, cysteine, and nonprotein thiols, total phenolic contents, and antioxidant potential (radical scavenging activity) was investigated in three cyanobacteria, viz. Nostoc muscorum, Phormidium foveolarum, and Arthrospira platensis. Selected fluence rate of UV-B caused enhancing effect on these parameters; however, the increased values of these attributes were greater in A. platensis followed by P. foveolarum and N. muscorum. Results indicate that UV-B (at selected fluence rate) could be used as technique that may modify cyanobacterial system for efficient and economic production of natural food supplements and/or natural pharmaceuticals.

Low and high doses of UV-B differentially modulate chlorpyrifos-induced alterations in nitrogen metabolism of cyanobacteria

The present study assessed the comparative responses on the specific growth rate, nitrogen metabolism and enzymes associated with nitrogen metabolism in two nitrogen fixing cyanobacteria—Nostoc muscorum and Phormidium foveolarum exposed to two UV-B doses (low; UV-BL: 0.5472kJm−2 and high; UV-BH: 5.472kJm−2) and two doses of the insecticide chlorpyrifos (O,O-diethyl O-3,5,6-trichloro-2-pyridyl phosphorothioate; low i.e. CPL, 1µgml−1 and high i.e. CPH, 2µgml−1) singly and in combination. The specific growth rate, NO3− and NO2− uptake, nitrate assimilating enzymes – nitrate reductase and nitrite reductase and ammonium assimilating enzymes – glutamine synthetase and glutamate synthase were severely affected when treated either with CPH or/and UV-BH while glutamate dehydrogenase exhibited a stimulatory response. CPL also reduced all the measured parameters (except GDH activity) after 24h, however, a stimulatory effect was observed after 72h due to an increase in nitrogen metabolism (and other antioxidant) enzymes during this period. UV-BL did not cause significant alteration in the studied parameters while in combination with CP doses, it either alleviated the inhibitory effects or further enhanced the CPL induced activities of these enzymes (except GDH). Overall results indicate the resistant nature of P. foveolarum against the inhibitory doses of UV-B and chlorpyrifos in comparison to N. muscorum.

Characterization and genomic analysis of a plaque purified strain of cyanophage PP

Cyanophages are ubiquitous and essential components of the aquatic environment and play an important role in the termination of algal blooms. As such, they have attracted widespread interest. PP was the first isolated cyanophage in China, which infects Plectonema boryanum and Phormidium foveolarum. In this study, this cyanophage was purified three times by a double-agar overlay plaque assay and characterized. Its genome was extracted, totally sequenced and analyzed. Electron microscopy revealed a particle with an icosahedral head connected to a short stubby tail. Bioassays showed that PP was quite virulent. The genome of PP is a 42,480 base pair (bp), linear, double-stranded DNA molecule with 222 bp terminal repeats. It has high similarity with the known Pf-WMP3 sequence. It contains 41 open reading frames (ORFs), 17 of which were annotated. Intriguingly, the genome can be divided into two completely different parts, which differ both in orientation and function.

Host re-identification of cyanophage PP and its implications for host range and specificity

In this study,we re-identified the hosts of cyanophage PP. Twenty-three candidate algal strains were tested,and the results indicated that seven strains belonging to Plectonema and Phormidium are the hosts of cyanophage PP,including two previously reported filamentous cyanobacteria,Plectonema boryanum and Phormidium foveolarum (Zhao et al. 2002).

Differential effects of UV-B radiation fluence rates on growth, photosynthesis, and phosphate metabolism in two cyanobacteria under copper toxicity

This work was undertaken to ascertain the impact of different fluence rates of ultraviolet-B (UV-B) radiation on two cyanobacterial biofertilizers, Phormidium foveolarum and Nostoc muscorum, growing under copper toxicity. Copper (2 and 5 µmol L−1) and high UV-B fluence rate (UV-BH; 1.0 µmol m−2 s−1) decreased the growth, pigment content, photosynthetic oxygen yield, phosphate uptake, and acid phosphatase activity in both the strains analyzed after 24 and 72 h of experiments, and combined exposure further enhanced the toxic effects. Respiration and alkaline phosphatase activities were stimulated appreciably. The damaging effect was shown on the order on pigments: phycocyanin > chlorophyll a > carotenoids, and on photosystems: whole chain photosynthetic reaction > photosystem II > photosystem I. Partial recovery in the photosystem II activity in the presence of artificial electron donors; diphenyl carbazide (DPC), hydroxylamine (NH2OH), and manganese chloride (MnCl2) pointed out the interruption of electron flow on the oxidation side of photosystem II. Unlike UV-BH, low UV-B fluence rate (UV-BL; 0.1 µmol m−2 s−1), rather than causing damaging effect partially, alleviated the toxic effects of Cu. This study suggests that the cyanobacterium P. foveolarum is less sensitive against UV-BH and excess Cu (2 and 5 µmol L−1), thus P. foveolarum may be used as a biofertilizer for sustainable agriculture.

I-PfoP3I: A Novel Nicking HNH Homing Endonuclease Encoded in the Group I Intron of the DNA Polymerase Gene in Phormidium foveolarum Phage Pf-WMP3

Homing endonucleases encoded in a group I self-splicing intron in a protein-coding gene in cyanophage genomes have not been reported, apart from some free-standing homing edonucleases. In this study, a nicking DNA endonuclease, I-PfoP3I, encoded in a group IA2 intron in the DNA polymerase gene of a T7-like cyanophage Pf-WMP3, which infects the freshwater cyanobacterium Phormidium foveolarum is described. The Pf-WMP3 intron splices efficiently in vivo and self-splices in vitro simultaneously during transcription. I-PfoP3I belongs to the HNH family with an unconventional C-terminal HNH motif. I-PfoP3I nicks the intron-minus Pf-WMP3 DNA polymerase gene more efficiently than the Pf-WMP4 DNA polymerase gene that lacks any intervening sequence in vitro, indicating the variable capacity of I-PfoP3I. I-PfoP3I cleaves 4 nt upstream of the intron insertion site on the coding strand of EXON 1 on both intron-minus Pf-WMP3 and Pf-WMP4 DNA polymerase genes. Using an in vitro cleavage assay and scanning deletion mutants of the intronless target site, the minimal recognition site was determined to be a 14 bp region downstream of the cut site. I-PfoP3I requires Mg2+, Ca2+ or Mn2+ for nicking activity. Phylogenetic analysis suggests that the intron and homing endonuclease gene elements might be inserted in Pf-WMP3 genome individually after differentiation from Pf-WMP4. To our knowledge, this is the first report of the presence of a group I self-splicing intron encoding a functional homing endonuclease in a protein-coding gene in a cyanophage genome.

Compatibility of ascorbate-glutathione cycle enzymes in cyanobacteria against low and high UV-B exposures, simultaneously exposed to low and high doses of chlorpyrifos

This study deals with the comparative responses of the two cyanobacteria viz. Nostoc muscorum and Phormidium foveolarum against single and combined doses of low (UV-BL, 0.1μmolm−2s−1) and high (UV-BH, 1.0μmolm−2s−1) fluence rates of ultraviolet-B radiation with low (CPL, 1μgml−1) and high (CPH, 2μgml−1) doses of the insecticide chlorpyrifos by measuring changes in growth, ascorbate-glutathione cycle enzymes and related metabolites. CPL and UV-BL both caused lesser increase in ROS but significantly stimulated AsA-GSH cycle enzymes. On the other hand, CPH and UV-BH posed inhibitory effects by enhancing ROS and inhibiting AsA-GSH cycle enzymes. Inhibitions in CPH or UV-BH treated samples were significantly prevented when they were supplemented with UV-BL and CPL (after 72h), respectively by lowering down ROS and enhancing AsA-GSH enzymes and related metabolites which manifested in terms of improved biomass accumulation.

Impact of low and high fluence rates of UV-B radiation on growth and oxidative stress in Phormidium foveolarum and Nostoc muscorum under copper toxicity: differential display of antioxidants system

In the present study, impact of low (UV-BL) and high (UV-BH) fluence rates of UV-B on growth, oxidative stress and antioxidant system was studied in two cyanobacteria i.e. Phormidium foveolarum and Nostoc muscorum under Cu (2 and 5 μM) toxicity after 24 and 72 h of experiments. UV-BH and Cu treatment decreased growth of both the cyanobacteria and Cu induced decrease in growth was accompanied by a significant increase in Cu accumulation. Levels of reactive oxygen species (ROS), i.e. superoxide radicals (SOR; \( \text O_{2}^{\cdot\,-} \)) and hydrogen peroxide (H2O2) were significantly increased by Cu and UV-BH exposure which in turn accelerated lipid peroxidation (malondialdehyde: MDA) and protein oxidation (reactive carbonyl groups: RCG). Activities of enzymatic antioxidants, such as superoxide dismutase (SOD), peroxidase (POD) and glutathione-S-transferase (GST) were increased by both doses of Cu as well as UV-B. Conversely, Cu and UV-BH drastically decreased catalase (CAT) activity. After the commencement of 24 h of treatment with Cu alone and together with UV-BH, non-protein thiols (NP-SH) contents were decreased while after 72 h, a reverse trend was noticed. Unlike NP-SH, cysteine content decreased appreciably during the treatments. In contrast to this, low dose (UV-BL) of UV-B did not influence growth, SOR, H2O2, MDA and RCG contents. An improvement in CAT activity and NP-SH content was observed under Cu and UV-BL treatment; hence, UV-BL treatment resulted into certain degree of protection against Cu toxicity in both the organisms. Thus, the results showed that UV-BH and UV-BL exerted differential effects on both the organisms under Cu toxicity, and compared to N. muscorum, P. foveolarum was less affected by Cu and UV-BH.

Differential physiological and biochemical responses of two cyanobacteria Nostoc muscorum and Phormidium foveolarum against oxyfluorfen and UV-B radiation

In the present study, degree of tolerance and tolerance strategies of two paddy field cyanobacteria viz. Nostoc muscorum and Phormidium foveolarum against oxyfluorfen (10 and 20 μg ml −1) and UV-B (7.2 kJ m −2 d −1) stress were investigated. Oxyfluorfen and UV-B decreased growth, photosynthesis, nutrient uptake, nitrate reductase, acid and alkaline phosphatase activities, which accompanied with the increase in the level of oxidative stress. However, growth was more affected in N. muscorum than P. foveolarum. Antioxidants exhibited differential responses against oxyfluorfen and UV-B stress. Ascorbate and proline levels were higher in P. foveolarum. A protein of 66 kDa was expressed in N. muscorum, however, it was absent in P. foveolarum than those of N. muscorum. Besides this, a protein of 29 kDa appeared in P. foveolarum under all the treatments, but it was present only in control cells of N. muscorum cells. Overall results indicated resistant nature of P. foveolarum against oxyfluorfen and UV-B stress in comparison to N. muscorum.

Genomic Analysis of Freshwater Cyanophage Pf-WMP3 Infecting Cyanobacterium Phormidium foveolarum: The Conserved Elements for a Phage

Cyanophages are ecologically abundant, genetically diverse in aquatic environments, and affect the population and evolutionary trajectories of their hosts. After reporting the cyanophage Pf-WMP4 genome (Liu et al. in Virology 366:28-39, 2007), we hereby present a related cyanophage, Pf-WMP3, which also infects the freshwater cyanobacterium Phormidium foveolarum. The Pf-WMP3 genome contains 43,249 bp with 234 bp direct terminal repeats. The overall genome organization and core genes of the two phages are comparable to those of the T7 supergroup phages. Compared with Pf-WMP4, cyanophage Pf-WMP3 has diverged extensively at the DNA level; however, they are closely related at the protein level and genome architecture. The left arm genes for the two phages, which mainly encode the DNA replication machinery, are not conserved in the gene order. Whereas the right arm genes of the two phages coding for structural proteins show high similarity in amino acid sequences and modular architecture, indicating that they have retained similar development strategies. The differences in similarity levels between the left and right arm genes suggest that the structural genes are the most conserved elements for a phage.

Solar radiation-driven decay of cyanophage infectivity, and photoreactivation of the cyanophage by host cyanobacteria

AME Aquatic Microbial Ecology Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials AME 48:13-18 (2007) - doi:10.3354/ame048013 Solar radiation-driven decay of cyanophage infectivity, and photoreactivation of the cyanophage by host cyanobacteria Kai Cheng1,2,3, Yijun Zhao2, Xiuli Du2, Yaran Zhang2, Shubin Lan2, Zhengli Shi1,* 1State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, PR China 2Hubei Key Laboratory of Urban Water, Environmental Ecology, Central China Normal University, Wuhan 430079, PR China 3Graduate School of Chinese Academy of Sciences, Beijing 100039, PR China *Corresponding author. Email: zlshi@wh.iov.cn ABSTRACT: Cyanophage PP (isolated from Plectonema boryanum and Phormidium foveolarum and named after the respective first letters of its 2 hosts) is a short-tailed, icosahedral-shaped, and double-stranded DNA virus and can be frequently detected with a high abundance and activity in many eutrophic lakes in Wuhan City, PR China. To understand how the virus survives solar UV-B damage, we examined the decay of cyanophage PP induced by solar UV-B radiation and the photoreactivation repair by host cyanobacteria, on 1 d in each of the 4 different seasons throughout a year. The UV-B transparent or non-transparent bag containing the cyanophage PP was exposed to sunlight at different water depths and was collected at varying time points. The collected sample was treated with or without radiation of a photoreactivating wavelength (300 to 500 nm). The decay ratio (here designated as the percentage of infectivity lost) for cyanophage PP from all samples caused by UV-B radiation ranged from 29.8 to 92.1%. Season and water depth were the main factors influencing the decay ratio, while long exposure time had less effect. The repair ratio (here designated as the percentage of revived infectivity by photoreactivation) for cyanophage PP reached a maximum during the first 1 to 3 h of exposure, at all depths. The maximum repair ratios of photoreactivation for each of the decayed samples, ranging from 7 to 59%, were negatively correlated with the decay ratio. In most cases, the repair ratio of photoreactivation reached a maximum in the first 4 h. Our results indicate that solar UV-B radiation may decrease the infectivity of cyanophage PP in shallow freshwater bodies in an extraordinarily fast and effective manner, whereas rapid photoreactivation may contribute to balancing the rapid phototoxicity. KEY WORDS: Cyanophage PP · UV-B · Decay ratio · Photoreactivation repair ratio Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in AME Vol. 48, No. 1. Online publication date: June 20, 2007 Print ISSN: 0948-3055; Online ISSN: 1616-1564 Copyright © 2007 Inter-Research.

Cyanophage Pf-WMP4, a T7-like phage infecting the freshwater cyanobacterium Phormidium foveolarum: Complete genome sequence and DNA translocation

We report the complete 40,938-bp genome sequence of a cyanophage, Pf-WMP4, which infects the freshwater cyanobacterium Phormidium foveolarum Gom. Nine of the forty-five potential open reading frames in the Pf-WMP4 genome share similarities with the genes found in T7-like phages. Using in vitro transcription, we found that seven promoters at the leftmost end of the genome can be recognized by the host RNA polymerase. By blocking transcriptional and translational inhibitors, we found that Pf-WMP4 DNA translocation, with an average translocation rate of 19.8 ± 2.7 bp s − 1 at 28 °C, requires both host transcription and protein synthesis of an unknown factor. Therefore the mechanism of cyanophage Pf-WMP4 DNA injection may be driven both by a T7-like internalization mechanism as well as an additional unknown mechanism requiring de novo protein synthesis. Our analysis of the Pf-WMP4 genome sheds new light on the translocation strategies and evolutionary traces of phages belonging to the T7 supergroup.

Screening of microalgae for species excreting norharmane, a manifold biologically active indole alkaloid

A screening of microalgae strains is described, with the objective to discover more species besides the known cyanobacterium Nodularia harveyana which excrete the manifold biologically active and co-mutagenic indole alkaloid norharmane (9H-pyrido(3,4-b)indole) into their environment. Seven more cyanobacterial species, Anabaena cylindrica, Anabaena inaequalis, Anabaenopsis siamensis, Chroococcus minutus, Nostoc carneum, Nostoc commune and Phormidium foveolarum, were newly discovered. The norharmane concentrations detected for cyanobacterial culture media varied in a species-dependent manner from less than 1 up to 525 microg l(-1). The risk for humans and livestock, resulting from the natural appearance of norharmane as an extracellular metabolite of various cyanobacteria, is discussed.

Petroleum Pollutant Degradation by Surface Water Microorganisms (8 pp)

It is well known that the composition of petroleum or some of its processing products changes in the environment mostly under the influence of microorganisms. A series of experiments was conducted in order to define the optimum conditions for an efficient biodegradation of petroleum pollutant, or bioremediation of different segments of the environment. The aim of these investigations was to show to what extent the hydrocarbons of a petroleum pollutant are degraded by microbial cultures which were isolated as dominant microorganisms from a surface water of a wastewater canal of an oil refinery and a nitrogen plant. Biodegradation experiments were conducted on one paraffinic, and one naphthenic type of petroleum during a three month period under aerobic conditions, varying the following parameters: Inorganic (Kp) or an organic medium (Bh) with or without exposition to light. Microorganisms were analyzed in a surface water sample from a canal (Pancevo, Serbia), into which wastewater from an oil refinery and a nitrogen plant is released. The consortia of microorganisms were isolated from the water sample (most abundant species: Phormidium foveolarum--filamentous Cyanobacteria, blue-green algae and Achanthes minutissima, diatoms, algae). The simulation experiments of biodegradation were conducted with the biomass suspension and crude oils Sirakovo (Sir, paraffinic type) and Velebit (Ve, naphthenic type). After a three month period, organic substance was extracted by means of chloroform. In the extracts, the content of saturated hydrocarbons, aromatic hydrocarbons, alcohols and fatty acids was determined (the group composition). n-Alkanes and isoprenoid aliphatic alkanes, pristane and phytane, in the aliphatic fractions, were analyzed using gas chromatography (GC). Total isoprenoid aliphatic alkanes and polycyclic alkanes of sterane and triterpane types were analyzed by GC-MS. Paraffinic type petroleums have a significant loss of saturated hydrocarbons. For naphthenic type petroleum, such a trend has not been observed. The most intensive degradation of n-alkanes and isoprenoid aliphatic alkanes (in paraffinic oil) and isoprenoids (in naphthenic oil) was observed using the inorganic medium Kp in the light; the microbial conversion is somewhat lower with Kp in the dark; with organic medium Bh in the light the degradation is of low intensity; with the same medium in the dark the degradation is hardly to be seen. Steranes and triterpanes were not affected by microbial degradation under the conditions used in our experiments. Obviously, the petroleum biodegradation was restricted to the acyclic aliphatics (n-alkanes and isoprenoids). Phormidium foveolarum (filamentous Cyanobacteria--blue-green algae) and Achanthes minutissima (diatoms, algae), microbial cultures isolated as dominant algae from a surface water in a wastewater canal of an oil refinery and a nitrogen plant, have degradable effects dominantly involving petroleum hydocarbons. Petroleum microbiological degradation is more intensive when inorganic medium (in the light) is applied. Having in mind that the inorganic pollutants have been released into the canal as well, this medium reflects more the natural environmental conditions. Polycyclic alkanes of sterane and triterpane type, in spite of the fact that these compounds could be degraded, have remained unchanged regarding abundance and distribution. Since this is the case even for naphthenic type petroleum (which is depleted in n-alkanes), it can be concluded that the biodegradation of petroleum type pollutants, under natural conditions, will be restrained to the n-alkane and isoprenoid degradation. Performed experiments and simulations of petroleum microbiological degradation may serve for the prediction of the fate of petroleum type pollutants, as well as for definition of conditions for bioremediation of some environmental segments.

Viability of dried vegetative cells or filaments, survivability and/or reproduction under water and light stress, and following heat and UV exposure in some blue-green and green algae.

Vegetative cells in dried, mucilagenous mass of Gloeocapsa aeruginosa and Aphanothece nidulans, reticulum of Hydrodictyon reticulatum, mucilagenous mass of Chroococcus minor, and filaments of Oedogonium sp. and Scytonema hofmanni died within 1/2, 1/2, 1/2, 1, 3 and 6 h, respectively, while dried vegetative filaments of Phormidium foveolarum retained under similar storage conditions viability for 4 d. P. foveolarum tolerated 1 mol/L NaCl. The resistance to desiccation in P. foveolarum exhibited similar dependence as that to heat or UV light. The water stress imposed on growing algae either on high-agar solid media or in NaCl-containing liquid media reduced at various levels or altogether inhibited the survival of vegetative parts in all, the cell division in C. minor, G. aeruginosa and A. nidulans, formation of heterocyst and false branch in S. hofmanni, oogonium in Oedogonium sp., and daughter net in H. reticulatum. Heat or UV shock of any level also produced similar effects as that by water stress. P. foveolarum tolerated low light level of 10 and 2 mumol m-2 s-1 and no light longer than the rest of other algae studied. Tolerance of microalgal forms to water, heat or UV stress depends primarily upon cell-wall characteristics or cell-sap osmotic properties rather than their habitats, morphology and prokaryotic or eukaryotic nature.

Growth potential and biocide tolerance of non-heterocystous filamentous cyanobacterial isolates from rice fields of Uttar Pradesh, India

Twenty-eight non-heterocystous filamentous cyanobacterial strains were isolated from different locations in the rice fields of Uttar Pradesh. These strains belonged to seven genera, namely Pseudanabaena, Limnothrix, Phormidium, Microcoleus, Plectonema, Lyngbya and Oscillatoria. A wide variation was observed in these strains with respect to dry weight, generation time and tolerance to biocides. Lyngbya palmarum and Oscillatoria acuminata showed maximum biomass (dry weight), while Pseudanabaena frigidum, Phormidium foveolarum, O. acuminata, Lyngbya palmarum and Lyngbya spiralis showed a significantly shorter generation time as compared to other strains studied. An interesting feature observed was that these non-heterocystous filamentous cyanobacteria possessed a remarkable tolerance to the biocides 2,4-dichlorophenoxyacetic acid, Malathion and Dimecron, at doses much higher than those recommended for rice crops.