Armoracia rusticana is the commercial source of the enzyme Horseradish Peroxidase (HRP). Calcium ions play an important role in the functional conformation of HRP. The present study assesses the effect of three calcium salts viz., calcium chloride (CaCl 2 ), calcium nitrate [Ca(NO 3 ) 2 ] and calcium sulphate (CaSO 4 ) on the guaiacol activity of crude peroxidase extracted from the shoots and roots of in vitro grown plantlets of A. rusticana and their growth medium. The highest activity was observed in the shoot extracts of 25 mM CaCl 2 treated plantlets (1.92 U/mL) and the root extracts of 25 mM Ca(NO 3 ) 2 supplemented plantlets (2.84 U/mL). The crude peroxidase activity of the medium containing 25 mM CaCl 2 supplement was highest (0.13 U/mL). The capacity of the shoot and root extracts to decolourise a 10 ppm solution of methyl orange over 48 hours, was also tested. The decolourisation capacity was highest in the shoot extracts from CaCl 2 treated plantlets (49.32%) and root extracts from Ca(NO 3 ) 2 treated plantlets (29.72%) respectively. Hence, the addition of calcium salts to growth medium enhances both peroxidase activity and decolourisation capacity of crude extracts of A. rusticana plantlets. These findings are of significance in enzymatic treatment for decolourisation of effluents containing dyestuffs.

The decolourisation of Methyl Orange (MO) and Bismarck Brown (BB) by crude peroxidase from Armoracia rusticana (Horseradish) was studied by varying different reaction parameters. The pH of the reaction mixture, initial dye concentration, amount of enzyme and hydrogen peroxide concentration were optimised for ambient temperatures (30 ± 2°C). The optimum pH for decolourisation was 4.0 (72.95 %) and 3.0 (79.24 %) for MO and BB, respectively. Also it was found that the Chemical Oxygen Demand of the enzyme-treated sample was significantly lower than that of the untreated controls for both dyes. The addition of a complex iron salt like Ferric EDTA was found to enhance the decolourisation of both dyes at pH 6.0, showing an increase of 8.69 % and 14.17 % in the decolourisation of MO and of BB, respectively. The present study explores the potential of crude peroxidase from horseradish to decolourise representative monoazo and diazo dyes, MO and BB, respectively. An attempt has been made to utilise a crude enzyme with appreciable activity obtained after minimal processing for the decolourisation of the aforesaid dyes. The findings of this study would find application in the enzymatic treatment of wastewater containing azo dyes.

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Aims: The fragrant flowers of Alstonia scholaris are rich in volatile compounds or essential oils, which comprise terpenes such as 1,8-cineole and linalool. The effects of the oils on the growth of Aspergillus niger were assessed for the first time in the present study. Study Design: Fungal growth assay. Place and Duration of Study: Sample: Department of Botany, St. Xavier’s College, Mumbai, between September 2006 and December 2006. Methodology: The volatile compounds of A. scholaris were extracted through steam distillation and hydrodistillation by using a Clevenger apparatus. The effect of the steam distillate (10% v/v) on the number of spores of A. niger was observed over 5 days. Furthermore, three fractions with distinct fragrances and boiling points were collected through hydrodistillation. The effects of each fraction on mycelial growth and sporulation in A. niger were examined. Accordingly, each hydrodistilled fraction was incorporated in growth medium (10% v/v) inoculated with fungal spores. The growth of the fungus was observed over 5 days. Distilled water was used as the control. All experiments were conducted in triplicate. Results: The fungal samples treated with steam distillates showed a significantly lower number of spores than the control after 5 days (165 ± 36 vs. 35 ± 7 spores/mL) at P ≤ .05. Furthermore, the fungal samples treated with the hydrodistilled fractions exhibited a delayed mycelial growth and sporulation compared with the control over 5 days. Fraction 1 was most effective in delaying mycelial growth (Day 4 vs. Day 1). Notably, on Day 4 none of the treated samples but the control sample exhibited sporulation. Conclusion: The volatile compounds of A. scholaris flowers clearly suppressed and delayed both mycelial growth and sporulation in A. niger but did not inhibit growth entirely. Hence, the floral volatile compounds exhibit fungistatic activity against A. niger.

Aluminium toxicity commonly affects plants and considerably reduces crop production. However, some plants, particularly tropical trees, have adapted to high aluminium concentrations by using strategies such as aluminium accumulation. The present study is the first report of aluminium hyperaccumulation in Alstonia scholaris, which is a common tree in Mumbai. Aluminium was accidently detected in the inflorescence tissue of A. scholaris. Volumetric analysis and atomic absorption spectrometry revealed that the aluminium concentration exceeded 1000 μg/g (dry weight). Notably, aluminium appeared to be stored in the fresh inflorescence stalks but not in the flowers. The aluminium concentration in the stalks determined through volumetric analysis was 10689.7±846.8 μg/g dry weight. Furthermore, the aluminium concentration in oven-dried stalks determined through atomic absorption spectrometry was 4080.36±11.60 μg/g. Because A. scholaris accumulates aluminium in its aerial parts at a concentration exceeding 1000 ppm, it can be considered a hyperaccumulator of aluminium. The high concentration of organic acids in the flowers indicated the possible role of organic acids in compartmentalization or sequestration of aluminium in the inflorescence stalks. Investigating the molecular and genetic basis of the mechanism(s) underlying aluminium sequestration in A. scholaris can provide important information for the development of crop varieties that are minimally affected by aluminium toxicity.