Biodegradation of C.I. Acid Blue 92 by Nasturtium officinale: Study of Some Physiological Responses and Metabolic Fate of Dye

The present study was conducted to evaluate the potential of aquatic vascular plant, Nasturtium officinale, for degradation of C.I. Acid Blue 92 (AB92). The effect of operational parameters such as initial dye concentration, plant biomass, pH, and temperature on the efficiency of biological decolorization process was determined. The reusability of the plant in long term repetitive operations confirmed the biological degradation process. The by-products formed during biodegradation process were identified by GC-MS technique. The effects of the dye on several plant physiological responses such as photosynthetic pigments content and antioxidant enzymes activity were investigated. The content of chlorophyll and carotenoids was significantly reduced at 20 mg/L of the dye. The activities of superoxide dismutase and peroxidase were remarkably increased in the plant root verifying their importance in plant tolerance to the dye contamination.     

Effects of Enhanced Ultraviolet-B (280–320 nm) Radiation on Growth and Photosynthetic Activities in Aquatic Fern Azolla Microphylla Kaulf

The effects of enhanced UV-B radiation on growth and photosynthetic activities were investigated in fronds of the aquatic fern Azolla microphylla Kaulf. The fronds were exposed to UV-B radiation intermittently once in 3 d during 12 d. Biomass and relative growth rate of UV-B treated Azolla plants and the heterocyst frequency of the UV-B treated symbiont decreased resulting in an increase in doubling time over the control. The doubling time was 3.08 d for control and 3.35 d for UV-B irradiated plants. Chl and carotenoid contents per unit fresh mass and photosystem 2 (PS2) activity also decreased under UV-B treatment. Measurements of photosynthetic activity in terms of fluorescence kinetics and PS2 mediated O₂ evolution showed that the aquatic fern Azolla is sensitive to UV-B damage.     

Biodegradation of direct blue 129 diazo dye by Spirodela polyrrhiza: An artificial neural networks modeling

Phytoremediation potential of the aquatic plant Spirodela polyrrhiza was examined for direct blue 129 (DB129) azo dye. The dye removal efficiency was optimized under the variable conditions of the operational parameters including removal time, initial dye concentration, pH, temperature and amount of plant. The study reflected the significantly enhanced dye removal efficiency of S. polyrrhiza by increasing the temperature, initial dye concentration and amount of plant. Intriguingly, artificial neural network (ANN) predicted the removal time as the most dominant parameter on DB129 removal efficiency. Furthermore, the effect of dye treatment on some physiologic indices of S. polyrrhiza including growth rate, photosynthetic pigments content, lipid peroxidation and antioxidant enzymes were studied. The results revealed a reduction in photosynthetic pigments content and in multiplication of fronds after exposure to dye solution. In contrast, malondialdehyde content as well as catalase (CAT) and peroxidase (POD) activities significantly increased that was probably due to the ability of plant to overcome oxidative stress. As a result of DB129 biodegradation, a number of intermediate compounds were identified by gas chromatography–mass spectroscopy (GC–MS) analysis. Accordingly, the probable degradation pathway of DB129 in S. polyrrhiza was postulated.     

Effects of paraquat on lipid peroxidation and antioxidant enzymes in aquatic fern <Emphasis Type="Italic">Azolla microphylla</Emphasis>

Paraquat is most extensively used methyl viologen herbicide to control weeds in the rice-Azolla ecosystem. The effects of different paraquat (PQ) dosages on growth, lipid peroxidation, and activity of antioxidant enzymes of Azolla microphylla Kaul. were investigated. The results indicated that Azolla fronds survived only at the concentrations of 2–6 μM PQ. Frond fragmentation and browning occurred after 24 h at 8 μM PQ. At 24 h, the amount of proteins decreased by 48.7 % in Azolla fronds exposed to 10 μM PQ than that in control fronds. The supplementation of 10 μM PQ increased the activities of superoxide dismutase (SOD), catalase (CAT), guaiacol peroxidase (GPX), and ascorbate peroxidase (APX) by 2,4-, 1,8-, 3,0-, and 2,2-fold, respectively, as compared with control. The content of PQ and activities of SOD, CAT, GPX, and APX were found to be positively correlated. Our study showed that PQ (2–6 μM) caused ROS overproduction in Azolla fronds, which were scavenged by induced activities of antioxidant enzymes.     

Effects of Se on the uptake of essential elements in Pteris vittata L.

Selenium has been proven to be an antioxidant in plants at low dosages. To understand better the mechanisms of Se toxicity and benefit to plants, more investigations about effects of Se on the uptake of essential elements in plants would be desirable. In this study, hydroponic (nutrient solution culture) and pot (soil culture) experiments were simultaneously conducted to investigate the effects of Se on the uptake and distribution of essential elements in Pteris vittata. L (Chinese brake fern), an arsenic (As)-hyperaccumulator and a selenium (Se)-accumulator. Chinese brake fern took up much more Se in nutrient solution culture than in soil culture, with the highest Se content recorded as 1,573 mg kg^?1 in the roots, demonstrating remarkable tolerance to Se. In soil culture, Chinese brake fern also accumulated high content of Se, with the highest content measured as 81 mg kg^?1 and 233 mg kg^?1, in the fronds and roots, respectively. In soil culture, the addition of Se suppressed the uptake of most measured elements, including magnesium (Mg), potassium (K), phosphorus (P), iron (Fe), copper (Cu) and zinc (Zn). In nutrient solution culture, when the Se content in the tissues of Chinese brake fern was relatively low, the supplementation of Se suppressed the uptake of most essential elements; however, with the increase of Se content, stimulation effects of Se on the uptake of Ca, Mg, K were observed. An initial decrease followed by a rapid increase of Fe content in the fronds of Chinese brake fern was found with Se addition and tissue Se content increasing in nutrient solution culture, suggesting antagonistic and synergic roles of Se on these elements under low and high Se exposure, respectively. We suggest that Ca, Mg, K may be involved in the tolerance mechanism of Se, and that the regulation of Fe accumulation by Se in the fronds might be partially due to the dual effects of Se on Chinese brake fern.     

Technical Note: Phytoremediation of Hg and Cd from Industrial Effluents using an Aquatic Free Floating Macrophyte Azolla Pinnata

The level of heavy metal pollution in Singrauli, an industrial region in India, was assessed and the phytoremediation capacity of a small water fern, Azolla pinnata R.Br (Azollaceae), was observed to purify waters polluted by two heavy metals, i.e., mercury (Hg) and cadmium (Cd) under a microcosm condition. Azolla pinnata is endemic to India and is an abundant and easy-growing free-floating water fern usually found in the rice fields, polluted ponds, and reservoirs of India. The fern was grown in 24 40-L aquariums containing Hg²⁺ and Cd²⁺ ions each in concentrations of 0.5, 1.0, and 3.0 mgL^?1 during the course of this study. The study revealed an inhibition of Azolla pinnata growth by 27.0–33.9% with the highest in the presence of Hg (II) ions at 0.5 mgL^?1 in comparison to the control. After 13 days of the experiment, metal contents in the solution were decreased up to 70–94%. In the tissues of Azolla pinnata, the concentration of selected heavy metals during investigation was recorded between 310 and 740 mgKg^?1 dry mass, with the highest level found for Cd (II) treatment at 3.0 mgL^?1 containing a metal solution.     

Interactive effects of selenium and arsenic on their uptake by Pteris vittata L. under hydroponic conditions

The interactive effects of selenium (Se) and arsenic (As) on plant uptake of Se and As have rarely been documented. In this study, the interactive effects of As and Se on their uptake by Chinese brake fern (Pteris vittata), an As-hyperaccumulator and Se-accumulator, were explored in two hydroponic experiments based on a two-factor, five-level central composite design. At Se levels of less than 2.5 mg L^?1, increasing amounts of As stimulated the uptake of Se in Chinese brake fern roots, possibly because of the beneficial effects of Se. In contrast, at Se concentrations greater than 2.5 mg L^?1, As suppressed the uptake of Se in Chinese brake fern roots. Uptake of As by both fronds and roots of Chinese brake fern was suppressed by the addition of Se, indicating the antagonistic effects of Se on As. In addition, at Se concentrations of less than 2.5 mg L^?1, As stimulated the translocation of Se from roots to fronds; meanwhile, the addition of Se resulted in reduced translocation of As from roots to fronds. These findings demonstrate the interactive effects of As and Se on their uptake by Chinese brake fern.     

EFFECTS OF NITROGEN AND PHOSPHORUS LEVELS,AND FROND-HARVESTING ON ABSORPTION,TRANSLOCATION AND ACCUMULATION OF ARSENIC BY CHINESE BRAKE FERN (PTERIS VITTATA L.)

This hydroponic experiment was conducted to determine the effects of nitrogen (N) and phosphorus (P) levels and frond-harvesting on the effectiveness of arsenic (As)-hyperaccumulator Chinese brake fern (Pteris vittata L.) to remove As from contaminated groundwater collected from south Florida. Three-month old ferns were grown in 38-L plastic tanks (two ferns per tank) containing 30-L of As-contaminated water (130 μg·L^?1 As), which was amended with modified 0.25 strength Hoagland's solution #2. Two N (26 or 52 mg·L^?1) and two P levels (1.2 and 2.4 mg·L^?1) were tested in one experiment, whereas the effect of frond-harvesting was tested in a separate experiment. Initially, N had little effect on plant As removal whereas low P treatment was more effective than high P and As was reduced to <5 μg·L^?1 in 28 d compared to 35 d. For well-established ferns, N and P levels had little effect. Reused fern, with or without harvesting the As-rich fronds, took up arsenic more rapidly so the As concentration in the groundwater declined faster (130 to ～10 μg·L^?1 in 8 h). Regardless of the treatments, most As (85–93%) was located in the aboveground tissue (rhizomes and fronds). Frond As concentrations were higher for non-harvested ferns than for ferns where fronds were partially harvested prior to treatment. Conversely, rhizomes accumulated more arsenic in ferns where fronds had been partially harvested. Low-P treatment coupled with reuse of more established ferns with or without harvesting fronds can be used to effectively remove arsenic from contaminated water using P. vittata     

Antimony accumulation and antioxidative responses in four fern plants

Antimony (Sb) toxicity and contamination has become a growing concern in recent years. Remediation of Sb contamination using plants may be an effective approach. This study aimed to investigate the potential of antimony (Sb) tolerance and accumulation by plants, as well as to understand the antioxidative responses to Sb. One set of hydroponic trials was set up using four species of fern plants, including Pteris cretica (PCA), Microlepia hancei (MH), Cyrtomium fortunei (CYF) and Cyclosorus dentatus (CYD). Ferns were grown for 2 weeks in nutrient solution containing a medium (5 mg L^?1) and a high (20 mg L^?1) rate of Sb, with no Sb added as the control. The biomass of fern PCA remained constant with Sb addition, whereas the biomass of ferns CYF, MH and CYD at the high Sb rate exposure decreased by 12.5%, 35.0% and 38.3%, respectively as compared with their controls. This suggests a high to low Sb tolerance order for these four fern plants. For all of these fern plants, more Sb was accumulated in the roots than in the fronds. Antimony concentration in the roots at the high rate of Sb addition was recorded, on average, as 358 mg kg^?1 for fern PCA, 224 mg kg^?1 for fern CYF, 124 mg kg^?1 for fern CYD and 123 mg kg^?1 for fern MH. A high rate of addition of Sb increased the contents of malondialdehyde (MDA) by 41.3% and 171.6% for ferns MH and CYD, respectively, as compared with their controls. No changes for MDA contents were observed in ferns PCA and CYF with Sb addition, indicating no lipid peroxidation reaction in these two plants. At a medium rate of Sb addition, the activities of peroxidase, catalase and ascorbate peroxidase in fern PCA were much higher than those in ferns CYF, CYD and MH, demonstrating the important role of these three enzymes in resisting Sb toxicity. The consistency in unchanged biomass, high accumulation of Sb in roots, lower MDA contents, as well as high enzyme production in fronds, indicated that fern PCA was more tolerant to Sb than the other three fern plants. Antioxidative enzymes (peroxidase, catalase and ascorbate peroxidase) might be involved in Sb toxicity resistance of fern PCA.     

Differential responses of hydrogen peroxide, lipid peroxidation and antioxidant enzymes in Azolla microphylla exposed to paraquat and nitric oxide

The present investigation was carried out to decipher the interplay between paraquat (PQ) and exogenously applied nitric oxide (NO) in Azolla microphylla. The addition of PQ (8 ??M) increased the activities of superoxide dismutase (SOD), catalase (CAT), guaiacol peroxidase (GPX), ascorbate peroxidase (APX) by 1.7, 2.7, 3.9 and 1.9 folds respectively than that control in the fronds of Azolla. The amount of H₂O₂ was also enhanced by 2.7 times in the PQ treated plants than that of control. The supplementation of sodium nitroprusside (SNP) from 8?C100 ??M along with PQ, suppressed the activities of antioxidative enzymes and the amount of H₂O₂ compared to PQ alone. The drop in the activity of antioxidative enzymes ?? SOD, GPX, CAT and APX was highest (39.9%, 48.4%, 41.6% and 41.3% respectively) on the supplementation of 100 ??M SNP with PQ treated fronds compared to PQ alone. The addition of NO scavengers along with NO donor in PQ treated fronds neutralized the effect of exogenously supplied NO. This indicates that NO can effectively protect Azolla against PQ toxicity by quenching reactive oxygen species. However, 200 ??M of SNP reversed the protective effect of lower concentration of NO donor against herbicide toxicity. Our study clearly suggests that (i) SNP released NO can work both as cytoprotective and cytotoxic in concentration dependent manner and (ii) involvement of NO in protecting Azolla against PQ toxicity.     

Light-Induced Adaptive Responses under Greenhouse and Controlled Conditions in the Fern Pteris cretica var. ouvrardii

The photosynthetic capabilities of the fern Pteris cretica var. ouvrardii were analysed by means of the light response curves of CO₂ exchange. In control growth conditions (greenhouse, low-light: 20–32 W m^?2); photosynthesis was shown to be saturated for low irradiance (20–25 W m^?2); the saturating photosynthetic rate, very low as compared to higher plants, was due to an extremely high intracellular resistance. When irradiance during the photosynthesis measurement was higher than 60–80 W m^?2, a constant decline of net CO₂ exchange as a function of time was observed. When irradiance during growth was enhanced, whether in greenhouse (20–250 W m^?2) or controlled (62 W m^?2) conditions, the first fronds that had developed in the new condition from the crosier stage exhibited decreased net maximal photosynthesis and a decreased efficiency in low light, but saturating irradiance was unmodified. However, the fronds whose entire differentiation (from meristem) occurred under these moderate irradiances (plants defoliated of all fronds and crosiers at the time of transfer), possessed more efficient photosynthetic characteristics than control plants. Pteris is able to grow under extreme shade conditions (4–8 W m^?2); light saturating photosynthesis and efficiency are higher under extreme shade than under control conditions. These adaptive characteristics indicate that Pteris is a well-adapted shade species.     

Changes in elemental content in fronds of Azolla filiculoides due to arsenic accumulation

This study analyzed the accumulation of arsenic and its influence on the content of P, Mn, Fe, Cu, Zn, S, Ca, Cl, and K in fronds of Azolla filiculoides via X-ray fluorescence (XRF). Azolla was exposed to increased concentrations of sodium arsenate (0, 5, 10, 20, and 30 μg ml ^? 1) in Yoshida's nutrient solution. After 96 h, fronds were collected and taken to constant weight to calculate the relative growth rate (RGR), the biomass duplication rate, the bioaccumulation factor (BAF), and the elemental concentration via XRF analysis. By increasing As concentrations the RGR and BAF were reduced. The greatest accumulation of As in fronds was achieved at 20 μg As ml ^? 1, which did not show significant differences with the highest concentration. Accumulation of As in fronds diminished concentrations of Mn, Fe, Zn, S, Ca, and K, while the concentration of P remained low but unchanging. The P content was significantly lower than the As content, thus the As:P ratio in fronds enhanced as the As concentration increased. Concentrations of Cl and Cu were unaffected due to As. This is one of the first reports about the influence of As-accumulation on the elemental content in Azolla fronds.     

Establishment and Control of Hay-scented Fern: A Native Invasive Species

Hay-scented fern (Dennstaedtia punctilobula (Michx.) Moore) is a native forest understory species that behaves as an invasive plant under certain conditions. Previous work has shown that both increased understory light intensity following overstory thinning and removal of competing plants by herbivores can lead to accelerated growth of hay-scented fern, allowing it to develop dense, nearly monospecific understories that inhibit tree seedling regeneration. To study the relationship between these two factors, we sampled 28 forest stands thinned at different times and subjected to different levels of browsing by white-tailed deer (Odocoileus virginianus), and concluded that more than 15 years of intensive browsing following thinning was necessary for ferns to form closed understory canopies with densities of >90 fronds/m² and canopy heights of 60–80 cm; thinning alone or intensive browsing alone was not sufficient to cause this level of fern invasion. We applied three treatments to dense fern understories to determine the relative importance of the fern canopy and the dense mat of roots, rhizomes, and dead fronds in the inhibition of tree seedling establishment. Results after two years were: (1) complete removal of the organic mat produced a large germination response of woody and herbaceous species; (2) mixing the organic mat into the mineral soil produced an initial germination response but poor seedling survivorship, as the fern canopy regrew to near pretreatment density; (3) repeatedly clipping the ferns for two years without disturbing the organic mat resulted in a lower germination response than the removal treatment, but rapid growth of seedlings.     

Seasonal and interspecific variation in the biochemical composition of some British fern species and their effects on Spodoptera littoralis larvae

Fern-feeding insects in Britain are mainly found on mature fronds in late summer. Six fern species (Dtyopteris filix-mas, D. dilatata, D. borreri, Phyllitis scolopendrium, Polyslkhum setiferum and Polypodium vulgare) were analysed for fibre, lignin, cellulose, tannins, cyanogenesis and thiaminase activity in an attempt to determine the biochemical basis for this seasonal pattern of attack. A bioassay was also carried out, using frond material incorporated in the diet of Spodoptera littoralis, to determine the effects of seasonal changes in fern toxins on a non-adapted, insect herbivore. The young fronds of all six species had a high protein content and low fibre-lignocellulose; protein levels decreased and cell wall materials increased as the fronds matured. Tannin concentrations and thiaminase activity showed a less consistent seasonal pattern. Tannins were present in the highest concentration in the young fronds of D. borreri, Polystichum and Polypodium and decreased with season; D. dilatata, Polystichum and Polypodium showed a similar pattern of thiaminase activity. The other species showed no strong seasonality in the levels of either tannins or thiaminase. No cyanogenic activity was detected in any of the fern species. Frond material from all six species decreased survivorship and growth rates of Spodoptera larvae. Larval performance and growth on diets containing fern material from young immature fronds was generally poorer than on diets containing material from mature fronds, collected later in the season. Neither tannin concentrations nor thiaminase activity levels closely corresponded to the observed interspecific and seasonal patterns of larval development and mortality, and other toxins must be involved. It is concluded that ferns are highly toxic to non-adapted herbivorous insects but the effects on adapted species are unknown. The restricted seasonal occurrence of a small number of insect species exhibiting specialized feeding habits suggests, however, that biochemical properties of the ferns determine this pattern of attack and limit the number of species which are able to exploit ferns as food resources.     

Characterization of glutathione reductase and catalase in the fronds of two Pteris ferns upon arsenic exposure

To better understand the mechanisms of plant tolerance to high concentration of arsenic, we characterized two antioxidant enzymes, glutathione reductase (GR) and catalase (CAT), in the fronds of Pteris vittata, an arsenic-hyperaccumulating fern, and Pteris ensiformis, an arsenic-sensitive fern. The induction, activation and apparent kinetics of GR and CAT in the plants upon arsenic exposure were investigated. Under arsenic exposure (sodium arsenate), CAT activity in P. vittata was increased by 1.5-fold, but GR activity was unchanged. Further, GR was not inhibited or activated by the arsenic in assays. No significant differences in K_m and V_max values of GR or CAT were observed between the two ferns. However, CAT activity in P. vittata was activated by 200 μM arsenate up to 300% compared to the control. Similar but much smaller increases were observed for P. ensiformis and purified bovine liver catalase (133% and 120%, respectively). This research reports, for the first time, the activation of CAT by arsenic in P. vittata. The increased CAT activities may allow P. vittata to more efficiently mediate arsenic-induced stress by preparing the fern for the impeding production of reactive oxygen species resulting from arsenate reduction to arsenite in the fronds.     

Changes in Pigment Composition and Photosynthetic Activity of Aquatic Fern (Azolla Microphylla Kaulf.) Exposed to Low Doses of UV-C (254 nm) Radiation

Changes in the content of pigments and rate of photosynthesis in Azolla microphylla Kaulf. fronds were measured during growth under solar and ultraviolet-C (UV-C) supplemented solar radiation. Maximum content of total chlorophyll (Chl) was observed on the 13^th day (termination of the experiment) of treatment in both control and treated plants. The treated plants had significantly lower total Chl and carotenoid contents than the control plants during the 1^st day of growth. After the 4^th day of exposure to UV-C supplemented solar radiation, the Chl and carotenoids accumulation increased in treated plants, so that the pigment concentration in the treated fronds was nearer to the control values after the 13^th day of treatment. Significant increase in UV absorbing pigments, anthocyanins, and flavonoids was observed at the 13^th day of treatment. In spite of the roughly similar photosynthetic pigment concentration, the photosynthetic activity measured as the rate of electron transport at photosystem 2 was only 65 % of the control values after 13 d of UV-C exposure. This revised version was published online in June 2006 with corrections to the Cover Date.     

Effect of phosphorus and nitrogen on growth,chlorophyll, amino nitrogen,soluble sugar contents and algal heterocysts of water fernAzolla pinnata

The P uptake inAzolla pinnata in mineral medium increased linearly with increasing phosphate doses and optimum growth and chlorophyll content of fern were recorded at 1.2 mM of K₂HPO₄. The higher doses of phosphate reduced growth and chlorophyll, but an increase in soluble sugar and amino nitrogen was noticed. Addition of combined nitrogen sources decreased the fern growth, soluble sugar, chlorophyll and heterocyst frequency but amino nitrogen was comparatively higher. The growth and chlorophyll content were always high when the fern was grown in the absence of added nitrogen sources; this supports the thesis about the specific importance of symbiosis for the nutrition of fern with nitrogen which cannot be replaced by mineral compounds.     

Phytoextraction potential of water fern (Azolla pinnata) in the removal of a hazardous dye,methyl violet 2B: Artificial neural network modelling

This study investigated the potential of Azolla pinnata (AP) in the removal of toxic methyl violet 2B (MV) dye wastewater using the phytoextraction approach with the inclusion of an Artificial Neural Network (ANN) modelling. Parameters examined included the effects of dye concentration, pH and plant dosage. The highest removal efficiency was 93% which was achieved at a plant dosage of 0.8 g (dye volume = 200 mL, initial pH = 6.0, initial dye concentration = 10 mg L^?1). A significant decrease in relative frond number (RFN), a growth rate estimator, observed at a dye concentration of 20 mg L^?1 MV indicated some toxicity, which coincided with the plant pigments studies where the chlorophyll a content was lower than the control. There were little differences in the plant pigment contents between the control and those in the presence of dye (5 to 15 mg L^?1) indicating the tolerance of AP to MV at lower concentrations. A three-layer ANN model was optimized (6 neurons in the hidden layer) and successfully predicted the phytoextraction of MV (R = 0.9989, RMSE = 0.0098). In conclusion, AP proved to be a suitable plant that could be used for the phytoextraction of MV while the ANN modelling has shown to be a reliable method for the modelling of phytoextraction of MV using AP.     

Optimization of triazo Acid Black 210 dye degradation by Providencia sp. SRS82 and elucidation of degradation pathway

The current work is aimed to evaluate the degradation of triazo textile dye Acid Black 210 (AB210) by Providencia sp. SRS82 that degrade 100 mg/L dye within 90 min under optimum conditions and was also found tolerant to as high as 2000 ppm of dye AB210. Optimum conditions for decolourization and degradation of AB210 with the isolate were viz. temperature 30 °C, pH 8, NaCl concentration 2.5% (w/v) and initial cell load of 8 × 10⁸ cells/mL under static condition. Induction of intracellular and extracellular lignin peroxidase, intracellular laccase and tyrosinase, azoreductase, and DCIP reductase indicated their contribution in the biodegradation of AB210. The products obtained from Providencia sp. SRS82 degradation was monitored through UV–Vis spectrophotometer and were characterized by FTIR, HPTLC, HPLC, GC/MS and LCMS. The proposed metabolic pathway for the biodegradation of AB210 is elucidated for the first time, which showed production of 4 molecules of benzene, one of naphthalene and 4-aminophenyl-N-(4-amino phenyl) benzene sulphonamide. Microbial toxicity and cytotoxicity studies revealed the comparatively less toxic nature of metabolites generated after degradation of AB210. Providencia sp. SRS82 was found competent to degrade actual effluent and diverse dyes that could be present in textile industry effluent showing usefulness of the organism for possible commercial application.     

Alteration in growth and thylakoid membrane lipid composition of <Emphasis Type="Italic">Azolla caroliniana</Emphasis> under phosphate deficiency

The changes in the fresh biomass accumulation, photosynthetic and anthocyanin pigments, photosystem 2 (PS 2) activity, ultrastructure of chloroplast, total lipids and fatty acid composition of thylakoid membrane were followed in the aquatic fern Azolla caroliniana grown on medium either deficient or supplied with various phosphorus concentrations. The content of photosynthetic pigments and the anthocyanin/chlorophyll ratio increased significantly with increasing PO₄ ³⁻ concentration. Phosphate deficiency inhibited growth and PS 2 activity and decreased content of total lipids and phospholipids in isolated thylakoids. This was accompanied with a significant increase in the percentage of galalactolipids.