an experimental study on citric acid production by aspergillus niger using gelidiella acerosa as a substrate ppt
Answers
Abstract
Citric acid (CA) is the most important commercial product which is produced by using various sugar substrates in the terrestrial environment. The present study made an attempt to produce citric acid by the fungal strain Aspergillus niger from red seaweed Gelidiella acerosa is the best alternative to sugar substrate in the marine environment. In this study three types of production media were prepared including control (sucrose) by following standard fermentation conditions. The acid production was indicated by the reduction of pH levels. The control medium gave the highest yield of 80 g/l at pH 1.5 and the medium containing crude seaweed powder and other compositions gave the yield of 30 g/l at pH 3.5 whereas the medium containing crude seaweed and 10% sucrose gave the yield of 50 g/l at pH 3.0. When calculating the benefit cost ratio, crude seaweed powder and 10% sucrose yielded 50 g of citric acid at the lower cost of Rs. 35, whereas the other two media gave the yield of 80 and 30 g respectively with the cost of Rs. 77 and 28. In economic point of view, the medium containing seaweed and 10% sucrose showed more benefit with lower cost.
Introduction
Citric acid (2-hydroxy-1,2,3-propanetricarboxylic acid) is the most important commercial product, which is found in almost all plant and animal tissues. It exists widely in the nature and present as a kind of fruit acid in lemon, orange, pine apple, plum, peas, peach and in animal bones, muscles and blood. It has many applications in food, pharmaceutical and cosmetic industries as an acidulant, flavour enhancer, preservative, antioxidant, emulsifier and chelating agent [5]. In recent years, citric acid has been commercially produced by fungal fermentation mainly by Aspergillus. niger [2]. Citric acid is also produced commercially using mutant fungal strains of Saccharomycopsis lipolytica, [3] Penicillium simplicissimum and Aspergillus. foeitidus [4]. A. niger are principally used to produce citric acid, however in culturing these fungi, the growth of Aspergillus in pellet form is desirable and this can be achieved by process optimization [5, 6]. Yarrowia lipolytica has the ability to produce citric acid from raw glycerol [7], a by-product of biodiesel production from rapeseed oil. Citric acid is produced commercially employing various inexpensive and readily available raw materials like molasses, carob pod extract, rape seed oil, corn-cobs, apple and grape pomace, kiwi-fruit peel, mandarine orange and brewery wastes have been used as carbon substrates [8] in terrestrial environment. Most reports are devoted to various types of citric acid producing yeasts and to experimental conditions governing production of citric acid, essentially based on shake flasks assays under undefined fermentation conditions. But there has been no report was found in use of marine sources, there is a need for finding the alternative carbon substrate from the marine environment. Marine environment has more and more number of beneficial sources in it, in this environment, seaweeds is easily available as well as renewable marine resources, which have enormous uses both in industrial and medicinal fields. Mostly all the living resources are rich in proteins, but the red seaweed, Gelidiella acerosa is highly rich in carbohydrates and very less in protein content [9]. G. acerosa is a red alga, which is commonly found in tide pools, high intertidal rocky areas and shallow sub-tides. This study was undertaken to explore alternate marine carbon sources and reports successful higher yields of citric acid using seaweed powder in shake flask fermentation at comparatively lower costs.
Materials and Methods
Aspergillus niger was isolated from the marine soil sample and identified by lactophenol cotton blue (LCB) mount method. The seaweed was collected from Rameswaram coastal area and brought to the laboratory and identification was made using the keys [10]. It was shade-dried for several days and then powdered mechanically. Seaweed powder was tested for its anti fungal activity against A. niger. Carbohydrate estimation [11] was carried out by following standard method. From the 7-days-old fungal culture, a loop-full of fungal spores was transferred to 5 ml of the sterile Potato dextrose broth and kept in rotary shaker for the formation of pellets. The production medium was prepared and the initial pH was adjusted to 6.5. Then the medium was sterilized at 15 lbs pressure and 121°C for 15 min. After sterilization, the medium was allowed to cool at room temperature. Then the pellet form of fungal culture was transferred and mixed in the sterilized production medium. The inoculated flask was placed into a water bath shaker at 30°C and 200 rpm for 10 days for proper aeration. The pH was checked in aseptic conditions at every 2 days of interval.
THIS IS VERY LONG BUT IT WILL HELP YOU
PLZ MARK IT AS BRAINLIEST