Fusarium proliferatum, an endophytic fungus from Dysoxylum binectariferum Hook.f, produces rohitukine, a chromane alkaloid possessing anti-cancer activity

Rohitukine is a chromane alkaloid possessing anti-inflammatory, anti-cancer and immuno-modulatory properties. The compound was first reported from Amoora rohituka (Meliaceae) and later from Dysoxylum binectariferum (Meliaceae) and Schumanniophyton problematicum (Rubiaceae). Flavopiridol, a semi-synthetic derivative of rohitukine is a potent CDK inhibitor and is currently in Phase III clinical trials. In this study, the isolation of an endophytic fungus, Fusarium proliferatum (MTCC 9690) from the inner bark tissue of Dysoxylum binectariferum Hook.f (Meliaceae) is reported. The endophytic fungus produces rohitukine when cultured in shake flasks containing potato dextrose broth. The yield of rohitukine was 186 μg/100 g dry mycelial weight, substantially lower than that produced by the host tissue. The compound from the fungus was authenticated by comparing the LC–HRMS and LC–HRMS/MS spectra with those of the reference standard and that produced by the host plant. Methanolic extract of the fungus was cytotoxic against HCT-116 and MCF-7 human cancer cell lines (IC₅₀ = 10 μg/ml for both cancer cell lines).     

Comparative research of chemical constituents,antifungal and antitumor properties of ether extracts of Panax ginseng and its endophytic fungus

The chemical compositions and bioactivities of ether extracts of an endophytic fungus Paecilomyces sp. isolated from Panax ginseng were reported, and the comparative analysis of the constituents, antifungal and antitumor properties of the ether extracts from this fungus and its host ginseng were also conducted. By means of GC/MS technique, 51 compounds of Panax ginseng and 38 compounds of Paecilomyce sp. were determined. It is attractive that the extracts derived from Paecilomyce sp. and ginseng samples contained the same compound falcarinol, a natural pesticide and anti-cancer agent. The ether extracts of Paecilomyce sp., tested at 7.8 μg/ml, completely inhibited the visible growth of Pyricularia oryzae. Furthermore, both extracts were tested against four human pathogenic fungi and showed the IC₈₀ of Paecilomyce sp. was 4 μg/ml against Trichophyton rubrum, equally to the control. Finally, the in vitro antitumor experience showed that the most of the IC₅₀ values were all being below 20 μg/ml.     

Liquid chromatography-tandem mass spectrometry method for determination of the pyridinium aldoxime 4-PAO in brain,liver, lung,and kidney

A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was validated and applied to the in vitro determination of 4-[(hydroxyimino)methyl]-1-octylpyridinium cation (4-PAO), which can penetrate the blood–brain barrier and reactivate acetylcholinesterase (AChE) inhibited by alkylphosphonate in the brain, liver, lung, and kidney. The limit of detection (LOD) was 0.235 μg cation/g wet weight, and the quantification range and linearity of the calibration curve extended over a range of 0.470–941 μg cation/g wet weight. For the proof of applicability, when 4-PAO was administrated intravenously via the rat tail vein at 10% LD₅₀, we were able to quantify the 4-PAO concentration in the tissues: brain 7.60 ± 1.32 μg cation/g wet weight (mean ± SD, n = 5), liver 26.8 ± 2.82 μg cation/g, lung 76.4 ± 24.9 μg cation/g, and kidney 638 ± 266 μg cation/g. In addition, the methods for 4-[(hydroxyimino)methyl]-1-decylpyridinium bromide (4-PAD) and 4-[(hydroxyimino)methyl]-1-(2-phenylethyl) pyridinium bromide (4-PAPE) were partly validated referring to the findings of the 4-PAO full validation. Thus, the LC-MS/MS method described in this study can be useful for quantification of pyridinium aldoxime methiodide (PAM)-type oximes in biological samples.     

Signal transducer and oxidative stress mediated modulation of phenylpropanoid pathway to enhance rosmarinic acid biosynthesis in fungi elicited whole plant culture of Solenostemon scutellarioides

This study aimed to improve rosmarinic acid (RA) production in the whole plant culture of Solenostemon scutellarioides through elicitation with phytopathogenic fungi. Amongst selected fungi, Aternaria alternata caused significant elevation (p < 0.05–0.01) in RA accumulation (∼1.3–1.6-fold) between 25 and 100 μg l⁻¹. However, elicitation at the dose of 50 μg l⁻¹ has been found to be most effective and intracellular RA content reached almost ∼1.6-fold (p < 0.01) higher in day 7. Therefore, A. alternata (50 μg l⁻¹) was selected for mechanism evaluation. A significant elevation of intercellular jasmonic acid was observed up to day 6 after elicitation with A. alternata (50 μg l⁻¹). A significant increase in tissue H₂O₂ and lipid peroxidation coupled with depletion of antioxidant enzymes superoxide dismutase and catalase indicated augmented oxidative stress associated with biotic interaction. Preceding the elicitor-induced RA accumulation, a notable alteration in the specific activities of biosynthetic enzymes namely PAL and TAT was recorded, while, no significant change in the activities of RAS was observed. HPPR activity was slightly improved in elicited plant. Therefore, it could be concluded that A. alternata elicited the biosynthesis of rosmarinic acid via signal transduction through jasmonic acid coupled with elicitor induced oxidative stress and associated mechanism.     

Dispersal pattern of airborne emissions from an aluminium smelter in Ouro Preto,Brazil, as expressed by foliar fluoride accumulation in eight plant species

In order to evaluate the dispersal pattern of airborne fluoride emissions, from a single source in the city of Ouro Preto, Brazil, the fluoride impact on some herbaceous plant species was studied using the plants as passive bioindicators. Foliar fluoride contents of eight species collected at different distances from an aluminium smelter were analyzed. The plant species were: Baccaharis dracunculifolia, Bidens pilosa, Borreria verticillata, Calopogonium mucunoides, Erigeron bonariensis, Hedychium coronarium, Ipomoea purpurea and Ipomoea cairica. In all species the fluoride accumulation decreased exponentially with the distance from the emission source. There was specific and distinct variation in fluoride accumulation among the species, a group of high-accumulator species (B. dracunculifolia and Bidens pilosa) and a group of low-accumulator species (I. cairica, H. coronarium and Borreria verticillata). C. mucunoides and E. bonariensis occupied an intermediate position. There was a pattern of plant contamination response during the periods analyzed. The plants nearest to the emission source, between 0.4 km northwest and 1.1 km east, showed fluoride contamination traits in leaves reaching values between 100 and 500 μg g⁻¹. Moreover, fluoride contents higher than 1000 μg g⁻¹ were found in these plants. At the most distant stations, situated 2.9 km northwest and 6 km east from the factory, the fluoride content of the dry matter was less than 10 μg g⁻¹ showing that plants at those distances were submitted to minimum contamination. There were different patterns of tolerance among the species analyzed. While B. dracunculifolia accumulated fluoride up to 1500 μg g⁻¹ in dry matter without any signs of injury, Borreria verticillata showed severe necrosis in leaves, but the fluoride content found was not higher than 120 μg g⁻¹.     

Diversity and heavy metal tolerance of endophytic fungi from six dominant plant species in a Pb–Zn mine wasteland in China

The diversity and metal tolerance of endophytic fungi from six dominant plant species in a Pb–Zn mine wasteland in Yunnan, China were investigated. Four hundred and ninety-five endophytic fungi were isolated from 690 tissue segments. The endophytic fungal colonization extent and isolation extent ranged from 59 % to 75 %, and 0.42–0.93, respectively, and a positive correlation was detected between them. Stems harboured more endophytic fungi than leaves in each plant species, and the average colonization extent of stems was 82 %, being significantly higher than that of leaves (47 %) (P ≤ 0.001, chi-square test). The fungi were identified to 20 taxa in which Phoma, Alternaria and Peyronellaea were the dominant genera and the relative frequencies of them were 39.6 %, 19.0 % and 20.4 %, respectively. Metal tolerance test showed that 3.6 mM Pb²⁺ or 11.5 mM Zn²⁺ exhibited the greatest toxicity to some isolates and they did not grow on the metal-amended media. In contrast, some isolates were growth stimulated in the presence of tested metals. The isolates of Phoma were more sensitive to Zn²⁺ than the isolates of Alternaria and Peyronellaea. However, the sensitivity of isolates to Pb²⁺ was not significantly different among Phoma, Alternaria, Peyronellaea and other taxa (P > 0.05, chi-square test). Our results suggested that fungal endophyte colonization in Pb–Zn polluted plants is moderately abundant and some isolates have a marked adaptation to Pb²⁺ and Zn²⁺ metals, which has a potential application in phytoremediation in this area.     

5-Nitro-2-furfuriliden derivatives as potential anti-Trypanosoma cruzi agents: Design,synthesis, bioactivity evaluation,cytotoxicity and exploratory data analysis

The anti-Trypanosoma cruzi activity of 5-nitro-2-furfuriliden derivatives as well as the cytotoxicity of these compounds on J774 macrophages cell line and FN1 human fibroblast cells were investigated in this study. The most active compounds of series I and II were 4-butyl-[N′-(5-nitrofuran-2-yl) methylene] benzidrazide (3g; IC₅₀ = 1.05 μM ± 0.07) and 3-acetyl-5-(4-butylphenyl)-2-(5-nitrofuran-2-yl)-2,3-dihydro,1,3,4-oxadiazole (4g; IC₅₀ = 8.27 μM ± 0.42), respectively. Also, compound 3g was more active than the standard drugs, benznidazole (IC₅₀ = 22.69 μM ± 1.96) and nifurtimox (IC₅₀ = 3.78 μM ± 0.10). Regarding the cytotoxicity assay, the 3g compound presented IC₅₀ value of 28.05 μM (SI = 26.71) against J774 cells. For the FN1 fibroblast assay, 3g showed IC₅₀ value of 98 μM (SI = 93.33). On the other hand, compound 4g presented a cytotoxicity value on J774 cells higher than 400 μM (SI >48), and for the FN1 cells its IC₅₀ value was 186 μM (SI = 22.49). Moreover, an exploratory data analysis, which comprises hierarchical cluster (HCA) and principal component analysis (PCA), was carried out and the findings were complementary. The molecular properties that most influenced the compounds’ grouping were C log P and total dipole moment, pointing out the need of a lipophilic/hydrophilic balance in the designing of novel potential anti-T. cruzi molecules.     

Hydrolysis of nitriles and amides by filamentous fungi

Screening of culture collection afforded nitrile-utilizing fungi belonging to genera Aspergillus, Talaromyces and Penicillium. Fusarium solani O1 was enriched from soil using 3-cyanopyridine as the sole source of nitrogen. This strain, and Penicillium multicolor CCF 2244 (the best one of the culture collection strains), showed comparable specific benzonitrile-hydrolyzing activities (0.95 and 0.87 μmol of benzoic acid h⁻¹ mg⁻¹ of dry cell weight at 28 °C, respectively). These fungi showed similar substrate specificities for substituted benzonitriles and heterocyclic nitriles but different pH and temperature optima (pH 8 and 38 °C for P. multicolor, pH 7 and 48 °C for F. solani). Amides as by-products were produced from some heterocyclic nitriles. Both fungi showed an amidase activity for nicotinamide.     

Isolation and bioelectrochemical characterization of novel fungal sources with oxidasic activity applied in situ for the cathodic oxygen reduction in microbial fuel cells

Brazilian filamentous fungi Rhizopus sp. (SIS-31), Aspergillus sp. (SIS-18) and Penicillium sp. (SIS-21), sources of oxidases were isolated from Caatinga's soils and applied during the in situ cathodic oxygen reduction in fuel cells. All strains were cultivated in submerged cultures using an optimized saline medium enriched with 10 g L⁻¹ of glucose, 3.0 g L⁻¹ of peptone and 0.0005 g L⁻¹ of CuSO₄ as enzyme inducer. Parameters of oxidase activity, glucose consumption and microbial growth were evaluated. In-cell experiments evaluated by chronoamperometry were performed and two different electrode compositions were also compared. Maximum current densities of 125.7, 98.7 and 11.5 μA cm⁻² were observed before 24 h and coulombic efficiencies of 56.5, 46.5 and 23.8% were obtained for SIS-31, SIS-21 and SIS-18, respectively. Conversely, maximum power outputs of 328.73, 288.80 and 197.77 mW m⁻³ were observed for SIS-18, SIS-21 and SIS-31, respectively. This work provides the primary experimental evidences that fungi isolated from the Caatinga region in Brazil can serve as efficient biocatalysts during the oxygen reduction in air-cathodes to improve electricity generation in MFCs.     

Novel pyrazole integrated 1,3,4-oxadiazoles: Synthesis,characterization and antimicrobial evaluation

A novel series of 2-(5-methyl-1,3-diphenyl-1H-pyrazol-4-yl)-5-phenyl-1,3,4-oxadiazoles 7(a–m) were synthesized either by cyclization of N′-benzoyl-5-methyl-1,3-diphenyl-1H-pyrazole-4-carbohydrazide 4a using POCl₃ at 120 °C or by oxidative cyclization of hydrazones derived from various arylaldehyde and (E)-N′-benzylidene-5-methyl-1,3-diphenyl-1H-pyrazole-4-carbohydrazide 5(a–d) using chloramine-T as oxidant. Newly synthesized compounds were characterized by analytical and spectral (IR, ¹H NMR, ¹³C NMR and LC–MS) methods. The synthesized compounds were evaluated for their antimicrobial activity and were compared with standard drugs. The compounds demonstrated potent to weak antimicrobial activity. Among the synthesized compounds, compound 7m emerged as an effective antimicrobial agent, while compounds 7d, 7f, 7i and 7l showed good to moderate activity. The minimum inhibitory concentration of the compounds was in the range of 20–50 μg mL⁻¹ against bacteria and 25–55 μg mL⁻¹ against fungi. The title compounds represent a novel class of potent antimicrobial agents.     

Salicylic acid-induced resistance to Fusarium oxysporum f. sp. lycopersici in tomato

We demonstrated that exogenous application of 200 μM salicylic acid through root feeding and foliar spray could induce resistance against Fusarium oxysporum f. sp. Lycopersici (Fol) in tomato. Endogenous accumulation of free salicylic acid in tomato roots was detected by HPLC and identification was confirmed by LC–MS/MS analysis. At 168 h of salicylic acid treatment through roots, the endogenous salicylic acid level in the roots increased to 1477 ng g^?1 FW which was 10 times higher than control plants. Similarly, the salicylic acid content was 1001 ng g^?1 FW at 168 h of treatment by foliar spray, which was 8.7 times higher than control plants. The activities of phenylalanine ammonia lyase (PAL, EC 4.3.1.5) and peroxidase (POD, EC 1.11.1.7) were 5.9 and 4.7 times higher, respectively than the control plants at 168 h of salicylic acid feeding through the roots. The increase in PAL and POD activities was 3.7 and 3.3 times higher, respectively at 168 h of salicylic acid treatments through foliar spray than control plants. The salicylic acid-treated tomato plants challenged with Fol exhibited significantly reduced vascular browning and leaf yellowing wilting. The mycelial growth of Fol was not significantly affected by salicylic acid. Significant increase in basal level of salicylic acid in noninoculated plants indicated that tomato root system might have the capacity to assimilate and distribute salicylic acid throughout the plant. The results indicated that the induced resistance observed in tomato against Fol might be a case of salicylic acid-dependent systemic acquired resistance.     

Patulin distribution in decayed apple and its reduction

Patulin is a mycotoxin produced by some species of the fungi Aspergillus and Penicillium, and is often detected in apple products. In this study spores from two fungal species that produce patulin were inoculated with a needle into apples about 1 mm below the skin. After incubation the apples were examined and then divided into 9 or 36 parts for patulin analysis. Patulin was analyzed by the UV–HPLC method. Apples inoculated with Penicillium griseofulvum showed no visual signs of decay and no patulin was detected. Extensive decay was observed on those apples that had been inoculated with Penicillium expansum and more than 1000 μg kg^?1 patulin was detected from the site of inoculation. Over 100 μg kg^?1 of patulin were detected in parts next to the inoculation site. However, only traces of patulin were detected in those areas where there were no visible signs of decay. Removal of the decayed part of the apple can significantly reduce patulin contamination in the final product.     

Immune responses,ROS generation and the haemocyte damage of scallop Chlamys farreri exposed to Aroclor 1254

The toxic effects of Aroclor 1254 (0.05, 0.5, 5 and 50 μg l^?1) on scallop (Chlamys farreri) immune system in vivo were studied. The results showed that Aroclor 1254 had significant toxic effect on the parameters tested in this paper (P < 0.05). The total number of haemocytes, the proportion of granulocytes, phagocytosis in all groups as well as the lysosomal membrane stability (LMS) in 5, 50 μg l^?1 and bacteriolytic activity 0.5, 5, 50 μg l^?1 treatments decreased significantly, while the proportion of hyalinocytes and the production of O₂^- in all treatments remarkably increased during the sampling time and tended to be stable gradually after 6–15 d. The bacteriolytic activity in 0.05 μg l^?1 treatments, LMS in 0.05, 0.5 μg l^?1 groups and the DNA damage (comet ratios and arbitrary values) in all treatments increased at the beginning of exposure and reached their peaks on day 1, day 1, day 6 and day 3, following that they all decreased gradually and became stable after 9–15 d. When the indices reached stability, except for DNA damage was higher than controls, the others were all significantly lower than those of controls (P < 0.05). Thus, Aroclor 1254 has evident toxic effects on scallop immune system, which supports the view that a relationship exists between pollution and immunomodulation in aquatic organisms. Also it supports the speculation that the PCBs pollution is one of the important reasons of the mass mortality of the C. farreri.     

Antimicrobial activity of Araucaria cunninghamii Sweet and the chemical constituents of its twigs and leaves

The present study was aimed at the identification of antimicrobial components from Araucaria cunninghamii with an activity-guided purification process. Eight compounds were obtained from the most active n-BuOH fraction and identified as the new compound 4-n-butoxyl-phenylpropanetriol (1), together with seven known compounds (2–8). These compounds were tested for antimicrobial activities against five bacteria and four plant pathogenic fungi. Within the series of compounds tested, compound 2 was the most active, particularly displaying moderate antibacterial activities against Erwinia carotovora and Bacillus subtilis with MICs 7.8 and 15.5 μg/ml. Moreover, this compound exhibited inhibitory activities against four plant pathogenic fungi: Helminthosporium sativum, Rhizoctonia solani, Fusarium oxysporum f. sp. Niveum and Fusarium oxysporum f. sp. Cubense, with EC₅₀ values of 42.3, 90.0, 62.7 and 100.2 μg/ml. To our knowledge, this is the first report that the n-BuOH fraction and compound 2 from A. cunninghamii showed inhibitory activity against plant pathogenic fungi.     

Effects of exposure to sublethal propiconazole on intestine-related biochemical responses in rainbow trout,Oncorhynchus mykiss

The effect of long-term (30 days) exposure to PCZ (0.2, 50, and 500 μg l^?1) on intestine-related biochemical markers in rainbow trout was investigated. Multiple biomarkers were measured, including digestive enzymes (proteolytic enzymes and amylase), antioxidant responses (TBARS, CP, SOD, CAT, GR and GPx) and energy metabolic parameters (RNA/DNA ratio, Na⁺-K⁺-ATPase). Exposure to 500 μg l^?1 PCZ led to significantly inhibited (p < 0.01) proteolytic enzyme and amylase activity. Activities of the antioxidant enzymes SOD, CAT, and GPx gradually increased at lower PCZ concentrations (0.2 and 50 μg l^?1). At the highest concentration (500 μg l^?1), oxidative stress was apparent as significant higher (p < 0.05) lipid peroxidation and protein carbonyls, associated with an inhibition of antioxidant enzymes activity. Moreover, energy metabolic parameters (RNA/DNA ratio, Na⁺-K⁺-ATPase) were significantly inhibited (p < 0.01) in the intestines of fish exposed to 500 μg l^?1 PCZ, compared with controls. We suggest that long-term exposure to PCZ could result in several responses in intestine-related biochemical markers, which potentially could be used as indicators for monitoring residual PCZ present in the aquatic environment.     

Domoic acid in a marine pelagic food web: Exposure of southern right whales Eubalaena australis to domoic acid on the Península Valdés calving ground,Argentina

The gulfs that surround Península Valdés (PV), Golfo Nuevo and Golfo San José in Argentina, are important calving grounds for the southern right whale Eubalaena australis. However, high calf mortality events in recent years could be associated with phycotoxin exposure. The present study evaluated the transfer of domoic acid (DA) from Pseudo-nitzschia spp., potential producers of DA, to living and dead right whales via zooplanktonic vectors, while the whales are on their calving ground at PV. Phytoplankton and mesozooplankton (primary prey of the right whales at PV and potential grazers of Pseudo-nitzschia cells) were collected during the 2015 whale season and analyzed for species composition and abundance. DA was measured in plankton and fecal whale samples (collected during whale seasons 2013, 2014 and 2015) using liquid chromatography coupled to tandem mass spectrometry (LC–MS/MS). The genus Pseudo-nitzschia was present in both gulfs with abundances ranging from 4.4 × 10² and 4.56 × 10⁵ cell l⁻¹. Pseudo-nitzschia australis had the highest abundance with up to 4.56 × 10⁵ cell l⁻¹. DA in phytoplankton was generally low, with the exception of samples collected during a P. australis bloom. No clear correlation was found between DA in phytoplankton and mesozooplankton samples. The predominance of copepods in mesozooplankton samples indicates that they were the primary vector for the transfer of DA from Pseudo-nitzschia spp. to higher trophic levels. High levels of DA were detected in four whale fecal samples (ranging from 0.30 to 710 μg g⁻¹ dry weight of fecal sample or from 0.05 and 113.6 μg g⁻¹ wet weight assuming a mean water content of 84%). The maximum level of DA detected in fecal samples (710 μg DA g⁻¹ dry weight of fecal sample) is the highest reported in southern right whales to date. The current findings demonstrate for the first time that southern right whales, E. australis, are exposed to DA via copepods as vectors during their calving season in the gulfs of PV.     

Development of a transparent,non-cytotoxic,silver ion-exchanged glass with antimicrobial activity and low ion elution

We investigated the antimicrobial, cytotoxicity, skin irritation, and ion elution behaviors of glass doped with silver ions with respect to its application to electronic equipment such as phones and tablet screens. The microbes tested were Escherichia coli, Staphylococcus aureus, and Penicillium funiculosum. AgNO₃ powder was spread on both sides of aluminosilicate glass, and it was heated to 250–280 °C for 10 min. Under optimized heating conditions (260 °C, 10 min), the antimicrobial activity of ion-exchanged glass against bacteria and fungi was over 99.9% after 24 weeks. The glass failed to irritate the skin of experimental animals and was considered non-cytotoxic. The maximum amount of Ag ions that were eluted from the ion-exchanged glass into drinking water was measured at 0.037 ± 0.003 μg L⁻¹, an amount which is several orders of magnitude below the standard limit of 0.1 mg L⁻¹ in drinking water. Ag ion-exchanged glass had characteristics suitable for use as a display screen, such as a light transmittance of 90% and a surface roughness of 0.704 nm. Our findings suggest that glass doped with silver ions is more hygienic than non-doped glass is, and should be applied to display screens and glassware.     

Effect of disease state on ionization during bioanalysis of MK-7009, a selective HCV NS3/NS4 protease inhibitor,in human plasma and human Tween-treated urine by high-performance liquid chromatography with tandem mass spectrometric detection

HPLC–MS/MS methods for the determination of a Hepatitis C NS3/NS4 protease inhibitor (MK-7009) in human plasma and Tween-treated urine were developed and validated over the concentration range 1–1000 ng/mL and 0.2–100 μg/mL respectively. A stable isotope labeled internal standard (ISTD), D₄-MK-7009, was employed. Analytes were chromatographed by reversed phase HPLC and quantified by an MS/MS system. Electrospray ionization in the positive mode was employed. Multiple reaction monitoring of the precursor to product ion pairs m/z 758.6 → 637.4 MK-7009 and m/z 762.5 → 637.4 ISTD was used for quantitation. Analyte and internal standard were extracted from 250 μL of plasma using an automated 96-well liquid–liquid extraction. Plasma pH adjustment prior to extraction minimized ionization suppression in plasma samples from patients with Hepatitis C. The urine method involved direct dilution in the 96-well format of 0.020 mL Tween-treated urine. These methods have supported several clinical studies. Incurred plasma sample reanalysis demonstrated adequate assay reproducibility and ruggedness.     

The effects of NH4+ and NO3− on growth,resource allocation and nitrogen uptake kinetics of Phragmites australis and Glyceria maxima

The effects of NH₄⁺ or NO₃⁻ on growth, resource allocation and nitrogen (N) uptake kinetics of two common helophytes Phragmites australis (Cav.) Trin. ex Steudel and Glyceria maxima (Hartm.) Holmb. were studied in semi steady-state hydroponic cultures. At a steady-state nitrogen availability of 34 μM the growth rate of Phragmites was not affected by the N form (mean RGR = 35.4 mg g⁻¹ d⁻¹), whereas the growth rate of Glyceria was 16% higher in NH₄⁺-N cultures than in NO₃⁻-N cultures (mean = 66.7 and 57.4 mg g⁻¹ d⁻¹ of NH₄⁺ and NO₃⁻ treated plants, respectively). Phragmites and Glyceria had higher S/R ratio in NH₄⁺ cultures than in NO₃⁻ cultures, 123.5 and 129.7%, respectively.Species differed in the nitrogen utilisation. In Glyceria, the relative tissue N content was higher than in Phragmites and was increased in NH₄⁺ treated plants by 16%. The tissue NH₄⁺ concentration (mean = 1.6 μmol g fresh wt⁻¹) was not affected by N treatment, whereas NO₃⁻ contents were higher in NO₃⁻ (mean = 1.5 μmol g fresh wt⁻¹) than in NH₄⁺ (mean = 0.4 μmol g fresh wt⁻¹) treated plants. In Phragmites, NH₄⁺ (mean = 1.6 μmol g fresh wt⁻¹) and NO₃⁻ (mean = 0.2 μmol g fresh wt⁻¹) contents were not affected by the N regime. Species did not differ in NH₄⁺ (mean = 56.5 μmol g⁻¹ root dry wt h⁻¹) and NO₃⁻ (mean = 34.5 μmol g⁻¹ root dry wt h⁻¹) maximum uptake rates (V_max), and V_max for NH₄⁺ uptake was not affected by N treatment. The uptake rate of NO₃⁻ was low in NH₄⁺ treated plants, and an induction phase for NO₃⁻ was observed in NH₄⁺ treated Phragmites but not in Glyceria. Phragmites had low K_m (mean = 4.5 μM) and high affinity (10.3 l g⁻¹ root dry wt h⁻¹) for both ions compared to Glyceria (K_m = 6.3 μM, affinity = 8.0 l g⁻¹ root dry wt h⁻¹). The results showed different plasticity of Phragmites and Glyceria toward N source. The positive response to NH₄⁺-N source may participates in the observed success of Glyceria at NH₄⁺ rich sites, although other factors have to be considered. Higher plasticity of Phragmites toward low nutrient availability may favour this species at oligotrophic sites.     

Ochrosin,a new biosurfactant produced by halophilic Ochrobactrum sp. strain BS-206 (MTCC 5720): Purification,characterization and its biological evaluation

A new bioactive molecule characterized as 4-dimethylaminobenzaldehyde (designated as Ochrosin) was isolated from a halophilic Ochrobactrum sp. strain BS-206 (MTCC 5720). Ochrosin exhibited good antimicrobial activity against both Gram-positive and Gram-negative bacteria and different Candida strains with minimum inhibitory concentration (MIC) values ranging from 4.68 to 150 μg mL⁻¹. It also exhibited anti-adhesive activity against various bacterial pathogens. Ochrosin caused an increase in the reactive oxygen species (ROS) levels to 32.4% and 28% and increased the NAD⁺/NADH ratio by 2.61 and 2.26 in S. aureus and E. coli, respectively. Ochrosin appears to interfere with ergosterol biosynthetic pathway in different Candida strains as it reduced the ergosterol content. Ochrosin showed insecticidal activity against three major stored-product grain pests like Tribolium castaneum, Callosobruchus chinensis and Sitophilus oryzae with LC₅₀ values of 7.3, 8.9 and 7.6 μg cc⁻¹, respectively. The anti-feedant index (ED₅₀) values observed were 1.07 and 1.35 μg cm⁻² of leaf area against Achaea janata and Spodoptera litura, respectively. This is the first report on Ochrosin, a multifunctional biosurfactant, produced by Ochrobactrum sp. BS-206 exhibiting promising antimicrobial, anti-adhesive, anti-feedant and insecticidal activities.