Antibiotic activity of two Anabaena species against four fish pathogenic Aeromonas species

Three organic extracts (chloroform, ethyl acetate and n-butanol) of ten cyanobacterial species (Anabaena solitaria, Anabaena variabilis, Anabaena cylindrical, Anabaena spiroides, Anabaenacircinalis, Oscillatoria ornate, Oscillatoria salins, Oscillatoria tenuis, Oscillatoria rubescens and Oscillatoria prolifica) were investigated for their antibacterial activities against 4 fish pathogenicbacterial species belonging to genus Aeromonas, namely, Aer. salmonicida, Aer. hydrophila, Aer. formicans and Aer. liquefaciens using oxytetracycline as reference antibiotic. Of all cyanobacterialsamples, only ethyl acetate extracts of A. variabilis and A. circinalis were proved to be the most effective against all tested Aeromonas species. Bioautographic investigation for 13 organic solventsystems indicate that the spot with Rf = 0.79 for A. variabilis and that of Rf = 0.84 for A. circinalis were the most effective. The median lethal doses (LD50) for the purified antibacterial compounds against micewere 246.67 and 231.67 mg/kg for that extracted from A. variabilis and A. circinalis, respectivel

Agricultural importance of algae

Algae are a large and diverse group of microorganisms that can carry out photosynthesis since they capture energy from sunlight. Algae play an important role in agriculture where they are used as biofertilizer and soil stabilizers. Algae, particularly the seaweeds, are used as fertilizers, resulting in less nitrogen and  phosphorous runoff than the one from the use of livestock manure. This in turn, increases the quality of water flowing into rivers and oceans. These organisms are cultivated around the world and used as human food  supplements. They can produce a clean and carbon-neutral food also and can be grown on abandoned lands and arid desert lands with minimal demands for fresh water. Seaweeds are an important source of iodine. Iodine levels in milk depend on what the cow producing the milk has been fed with. Feeding milk cattle with seaweeds can increase the quantity of iodine in milk, according to Fuzhou Wonderful Biological Technology. Egg-laying rate in hen is also increased by algae feed additives. In this article, we discussed the most important aspects of algae and its agricultural uses to those who work in this area.Key words: Algae, seaweeds, agriculture, biofertilizer, soil stabilizers

Algae and Cyanobacteria as Biocontrol Agents of Fungal Plant Pathogens

none2noAbstract: Since long time, algae are used in agriculture as soil amendment for their beneficial effects on plant health and productivity. In fact, algae contain several molecules such as plant growth hormones (cytokinins, auxins, abscisic and gibberellic acid), polysaccharides, betaines and micronutrients. The research on algae, their compounds and their effects on plants have started in the middle 1950s and brought to the formulations of liquid products containing extracts with compounds readily available for plants. The algae extracts, besides having effects on plant growth, have demonstrated to improve plant resistance to both abiotic and biotic stresses. Among biotic stresses, algae showed antifungal activity against different pathogens especially of horticultural plants. From the middle of last century, plant management has always been dependent from the market demand that required growing quantity of ‘perfect’ fruits and vegetables over the year. In this scenario, the chemical industry of fertilizers and pesticides developed new products that have been used for years. In particular, pesticides have represented the base of the management of fungal plant pathogens. During the last decades, the use of both pesticides and chemical fertilizers has represented a serious risk for human health and brought disorder of ecosystem equilibrium. Consequently, algae for their biostimulant and antifungal effects may be considered useful tools to reduce the input of chemicals in integrated pest management strategies. In line with these strategies, the European Regulation EC 1107/2009, concerning the placing of plant protection products on the market and repealing Council Directives 79/117/ EEC and 91/414/EEC, recommends that priority should be given to non-chemical and natural alternatives wherever possible.mixedHillary Righini; Roberta RobertiHillary Righini; Roberta Robert