Tanveer Abbas

Effects of Different Physical and Chemical Parameters on Phosphate Solubilization Activity of Plant Growth Promoting Bacteria Isolated from Indigenous Soil

The microorganisms play a vital role in fertility of soil and hence favors’ large group of plants. In present study we have successfully isolated certain bacteria from soil including both Gram positive and Gram negative bacteria and access their ability in phosphate solubilization. Effects of temperature, pH and different carbon sources, on phosphate solubilization, by these isolates were also determined. Low temperature 25 °C, pH between 5-7, and glucose as carbon source were found to be best for phosphate solubilization by most of the isolates. Present study highlights the importance of these plants growth promoting bacteria and their uses for agriculture purposes.

New antimicrobial flavonoids and chalcone from Colutea armata

Colucins A (1) and B (2), new flavonoids and colucone (3), the new chalcone derivative, have been isolated from the CHCl3-soluble fraction of the whole plant of Colutea armata along with luteolin (4), luteolin 7-O-β-D-glucoside (5), isoliquiritigenin (6), trans-caffeic acid (7) and stigmasterol (8) reported for the first time from this species. Their structures were elucidated by spectroscopic techniques including MS and 2D-NMR spectroscopy. Compounds 1 and 2 showed significant antimicrobial activity against two Gram positive and three Gram negative bacterial strains while 3 was moderately active.

Effect of Taro (Colocasia esculenta) Starch-Hydrocolloids Mixture on the Physical and Sensory Characteristics of Leavened Bread

During this study, different blends of taro starch-hydrocolloid were incorporated in yeast leavened bread and their effects were investigated. The specific volume, moisture content and slice shape of the bread were found to be improved by the addition of taro starch-guar gum blend. Taro starch-xanthan gum mixture was also found to be a good additive to improve specific volume, slice shape, crumb softness as well as sensory characteristics of bread. The study reveals taro starch-hydrocolloid blend can be utilized as a novel ingredient to improve the physical and sensory characteristics of leavened bread.

Effect of guar gum coatings containing essential oils on shelf life and nutritional quality of green-unripe mangoes during low temperature storage

This study investigated the effect of treatment of guar gum coating coupled with essential oils. Harvested unripe green mangoes (UGM) were preserved using edible coatings containing essential oils of Nigella sativa, Coriandrum sativum, Foeniculum vulgare and Laurus nobilis derived using two different solvents (methanol and ethanol) and stored at refrigeration temperature (10°C, 80-85% relative humidity). Physiological and biochemical parameters that assess the quality of fruits were determined. Microbiological analysis was also performed at the start and end of shelf life. Generally, it was observed that ethanolic essential oils supplemented coatings conferred a greater retention of fruit quality as compared to both controls. Bacterial counts were significantly reduced in fruits that were coated with ethanolic essential oil edible coatings. Secondly, the coatings supplemented with ethanolic and methanolic essential oils extended shelf life up to 24days whereas treated and untreated control decayed after 10 and 6days respectively (P<0.05). These results suggested the application of these edible coatings for preservation of unripe green mangoes during cold storage.

Bioactive Metabolites from Indigenous Actinomycetes Isolated from Marine Water

Microbial natural products have continued to play an important role in the discovery of novel chemicals for the development of important therapeutic agents. Actinomycetes form a potent reservoir of biologically active secondary metabolites and enzymes. The need for finding novel bioactive compounds for the development of new therapeutic agents is required due to the emergence of antibiotic resistance among pathogenic bacteria. Actinomycetes are considered as one of the best producers of variety of antagonistic compounds that could serve as potential chemotherapeutic agents. The present study was undertaken to find new antagonistic compounds from actinomycetes. Actinomycetes were successfully isolated from marine water samples collected at various locations of Karachi. Initially 39 isolates were collected out of which 23 were found to produce active metabolites against one or more test bacterial cultures. Actinomycetes strains IS26, IS33, and IS39 showed significant potential of having bioactive metabolites. Further, the spectrum of those strains was tested against gram positive and gram negative bacteria and results showed variable potential of actinomycetes to inhibit bacterial growth.

Effect of Taro Starch-Hydrocolloids Mixture as a Functional Ingredient on the Quality of Milk Dessert

The study was carried out to investigate the effect of taro starch-hydrocolloids mixture on the physical and sensory properties of milk dessert. Four different hydrocolloid i.e. arabic, Carboxymethyl cellulose (CMC), guar and xanthan gums were mixed with taro starch in different concentration and their potential use in milk dessert as functional ingredients were evaluated. Physical and sensory characteristics were found to be considerably improved in different aspects by adding these functional ingredients. Taro starch-arabic gum blend was observed to be an effective additive to produce creamy texture of milk dessert. Syneresis from dessert was noted to be diminished and sensory characteristics were also found to be improved by adding taro starch-guar gum blend. Similarly, taro starch-xanthan gum blend has effectively been stabilized the texture and sensory properties of milk dessert.