FACULTY OF BIOSCIENCES
ABSTRACT
Anthropogenic influence of water resource is a global problem. The major pollutants such as dye stuffs from the textile industries affect the aquatic ecosystem. Due its toxicity it increases the Biological Oxygen Demand (BOD) and also depletes the oxygen in water. The conventional methods such as extraction, steam distillation, absorption, filtration etc., will have drawbacks of incomplete removal of dye stuffs. Enzymes reduces their adverse impact on the environment thereby making enzymatic wastewater treatment an ecologically sustainable technique. Two hundred and forty isolates were isolated from the cow dung, compost, soils where the hides and skin of animals were burnt. Three isolates displayed clear zones of inhibition characteristic of Actinomycetes. The isolates were further characterized by examining their colony morphology, cover slip culture techniques, gram staining reaction and amylase activity. The α-amylase activity was determined on solid medium supplemented with starch. The detection α-amylase activity of the isolates was based on the formation of clear zones around the colonies when flooded with iodine. The decolourization abilities of the isolates were also determined. The isolates showed good absorption characteristics and degrading capacity on the dye Congo red and brilliant green. It showed that Actinomycetes are potential decolorizer of dye stuffs and are good biosorbent.
Introduction
Environmental pollution is one of the serious issues of concern in developing countries such as Nigeria. This could be due to industrial activities. Industrialization being a welcomed development has its negative side effects. The major pollutants such as dye stuffs from the textile industries affect the aquatic ecosystem. Due to its toxicity it increases the Biological Oxygen Demand (BOD) and also depletes the oxygen in water. The effluent discharge lead to pollution of the ground water. (Bello et al., 2013). Textile effluents have been found to contain a higher amount of metals especially chromium, copper, lead and cadmium. The metals are used in the production of color pigments of textile dyes. The toxic effect of dye stuffs and other organic compounds as well as acidic and alkaline contaminants from industrial establishments are widely unacceptable due to increased awareness of environmental issue.
Textile industry is one of the oldest and largest industries of. Synthetic dyes are coloring agents mainly used in textile industries which generate a huge amount of wastewater in the process of dyeing. It is estimated that these industries discharge around 280,000 tons of dyes every year into the environment. Discharge of these colored effluents into rivers and lakes results in the reduction of dissolved oxygen concentration, thus creating anoxic condition and leading to the acute toxic effects on the flora and fauna of the ecosystem. Azo dyes constitute the largest and most versatile class of synthetic dyes used in the textile industry due to their ease in production and variety in color compared to natural dyes (Pandey et al., 2007). Organisms such as Actinomycetes have been shown to specifically degrade azo dyes.
A dye can generally be described as a colored substance with an affinity to the substrate to which it is applied. Two percent of dyes produced are discharged into aqueous effluents while ten percent is subsequently lost during textile coloration process. (Easton 1995). Apart from the toxicological properties of dyes, their color is one of the first signs of contamination in a waste water.
It is therefore of great necessity to isolate thermophilic Actinomycetes from natural sources like cow dung, compost and soil when the hides and skins of cows were burnt to isolate, characterize thermophilic halophilic Actinomycetes and their ability to degrade and absorb dyes.
Effluents released from the textile industry are usually discharged into water bodies half treated or untreated (Bello et al., 2009). These dyes and other allied chemicals contribute to a major pollution load of the receiving water bodies .The major constituents of effluent discharged by dye is the color. It is the contaminant to be recognized in waste water and the presence of its very small amount in waste water is highly visible and undesirable. Synthetic dyes are used alongside with other toxic metals and the discharge of their effluents could have a very hazardous effect on the environment
Actinomycetes belong to the phylum Actinobacteria, which represents one of the largest taxonomic units currently recognized within the Domain Bacteria (Ventura et al., 2007). They are commonly believed to have a role in the recycling of nutrient and some exists as aerobes and some are anaerobes and are rich source of secondary metabolites with diverse biological activity.
Actinomycetes are a group of prokaryotic organisms belonging to subdivision of the gram- positive bacteria phylum. The Actinomycetes (order Actinomycetales) are bacteria that tend to form branching filaments which in some families develop into mycelium. They are regarded as higher bacteria because of this mycelia character. These bacteria closely resemble fungi in overall morphology. They are distinguished from other bacteria by their morphology DNA rich in guanine plus cytosine and on the basis of nucleic acid sequencing and pairing studies. The soil Actinomycetes produce a volatile compound called geosmin, which literally translates to “earth smell”. This organic substance contributes to the typical odour one gets when rain falls on soil (Uzel et al., 2011). Actinomyctes may be aerobic or anaerobic, although the thermophilic forms are primarily aerobic.
Actinomycetes are grouped as mesophilic, thermophilic and psychrophilic. The majority of them are mesophilic, growing at temperatures ranging from 18oC to 40oC. A few are thermophilic, which means that they have an optimum temperature for growth at 55oC and above. These thermophilic Actinomycetes exist in soil, compost heaps, heating hays. The group of Actinomycetes are Thermoactinomyces, Streptomyces and Thermomonospora species (Gousterovac et al., 2014). Thermophiles are the most primitive organisms which are important biotechnologically for thermostability, less incubation time, early sporulation and immense industrial feasibility. Many mesophilic Actinomycetes are active in compost in the initial stage of decomposition.
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