Search or add a thesis

Advanced Search (Beta)
Home > Biodegradation of Azo Dyes by Bacterial Cells and Azoreductase

Biodegradation of Azo Dyes by Bacterial Cells and Azoreductase

Thesis Info

Access Option

External Link

Author

Imran, Muhammad

Program

PhD

Institute

University of Agriculture

City

Faisalabad

Province

Punjab

Country

Pakistan

Thesis Completing Year

2013

Thesis Completion Status

Completed

Subject

Soil Sciences

Language

English

Link

http://prr.hec.gov.pk/jspui/handle/123456789/998

Added

2021-02-17 19:49:13

Modified

2024-03-24 20:25:49

ARI ID

1676725601134

Asian Research Index Whatsapp Chanel
Asian Research Index Whatsapp Chanel

Join our Whatsapp Channel to get regular updates.

Similar


Azo dyes are widely used by different industries including the textile industry. In Pakistan, dye-containing industrial wastewater is commonly used to irrigate crops, which leads to the contamination of agricultural soils. These azo dyes may influence soil microbes adversely. Hence, a study was conducted to assess the persistence of azo dyes in soil and their impact on soil microbial community structural changes. Furthermore, biodegradation of these azo dyes by bacterial cells and enzyme azoreductase was examined in the liquid medium. Three azo dyes such as Direct Red 81, Reactive Black 5 and Acid Yellow 19 were added into 10 g soil at concentration of 160 mg kg-1 soil. Azo dyes were found to be quite stable and degraded slowly in the soil. A substantial amount of Direct Red 81 (63.5%), Reactive Black 5 (17.3%) and Acid Yellow 19 (24.6%) was recovered from soil upon treatment with a mixture of four solvents (water, methanol, acetone, chloroform, 1:1:1:1 v/v) after 14 days of spiking. Phospholipid fatty acid (PLFA) analysis showed significant changes in the soil microbial community structure after treatment of the soil with azo dyes compared to untreated soil. To prevent contamination of soil, dye-contaminated wastewater discharged by dyeing units requires treatment prior to its release into water streams and soil. For this purpose, thirty bacterial strains capable of degrading azo dyes were isolated from wastewater of textile industry. Isolate IFN4 was identified by 16S rRNA gene sequencing. It belonged to genus Shewanella and was named as Shewanella sp. strain IFN4. This bacterium was highly efficient in decolorizing four, structurally different azo dyes (200 mg L-1) individually as well as in mixture, and 72-99% decolorization was achieved just in 4 h under static incubation. Optimum pH and temperature for the decolorization of dye mixtures were 8.5 and 35 °C, respectively. Decolorization of the dyes was dependent on the presence of co-substrate in medium, and yeast extract was used preferably by the strain IFN4 as a co-substrate for the decolorization of dye mixtures compared to other co-substrates. Maximum decolorization occurred when the dye solution was supplemented with 6 g L-1 yeast extract. Moreover, azoreductase activity of strain IFN4 was significantly higher in the dye solution containing 2 g L-1 yeast extract (4.19 U/mg proteins) than that observed without yeast extract (1.32 U/mg proteins). Michaelis-Menten kinetics was employed to calculate Km and Vmax values for crude proteins of strain IFN4, and were 0.062 g L-1 yeast extract and 4.44 U/mg proteins, respectively. Among the components (riboflavin, pyridoxine and thiamine) of yeast extract, only riboflavin enhanced the decolorization of azo dyes by bacterial cells and azoreductase. Textile wastewater contains toxic heavy metals and salts, thus decolorizing activity of strain IFN4 and its azoreductase was evaluated in the presence of various metals and salts. The decolorization efficiency of Shewanella sp. strain IFN4 was not affected by the addition of Ni2+, Cr2+, Pb2+, Fe3+ and Mn2+ in liquid medium containing 200 mg L-1 Reactive Black 5. However, addition of Cu2+, Zn2+, Co2+ and Cd2+ substantially reduced the decolorization rate. Cd2+ was highly toxic as no decolorization was observed at concentration of 10 mg L-1. In contrast, strain IFN4 was able to decolorize Reactive Black 5 dye efficiently in the presence of metal ion mixture with concentration up to 15 mg L-1 dye solution. The results also revealed that Zn2+, Co2+, Cd2+ and Cu2+ inhibited bacterial growth while Fe3+ and Mn2+ enhanced it. The metal ions did not cause a significant inhibition in the azoreductase activity except Cu2+. Furthermore, strain IFN4 was able to decolorize Reactive Black 5 at salt concentration of 50 g NaCl L-1 and 60 g Na2SO4 L-1. However, this strain was unable to decolorize Reactive Black 5 in the presence of even 2 g NaNO3 L-1 medium. Azoreductase activity of strain IFN4 was not significantly decreased at salt concentration of 30 and 60 g L-1 Na2SO4 and NaCl, respectively. However, a significant inhibition in the enzyme activity was observed above these concentrations. Moreover, azoreductase of strain IFN4 showed broad substrate specificity and maximum decolorization of azo dyes was observed at pH 8.0 and 45 °C. Azoreductase activity was dependent on coenzymes (NADH or NADPH), flavin and quinone compounds as enzyme activity increased by their presence in the assay. The azoreductase of Shewanella sp. strain IFN4 had a molecular mass of 33±0.5 kDa and was identified as Na (+)-translocating NADH-quinone reductase subunit F. This study suggested that Shewanella sp. strain IFN4 and its azoreductase are the potential tools to treat textile wastewater.
Loading...
Loading...

Similar Books

Loading...

Similar Chapters

Loading...

Similar News

Loading...

Similar Articles

Loading...

Similar Article Headings

Loading...

۴۷۔ میں اور تُو

میں اور تو

ہماری زندگی ہے کچھ یوں منتشر

جیسے دو متوازی خطوط کا سفر

نہ ابتدا میں لچک

نہ انتہا پہ خم

بس محو ِ سفر ہیں

نہ ابتدائے سفر کا جنوں

نہ وصال منزل کی لذت

فقط اک خلا ہے

جو درمیاں پڑا اونگھ رہا ہے

یہ ’’تُو‘‘،’’میں‘‘کے دو خطوط

شاگرد کے خلاف تادیبی کاروائی کا دائرہ کار سنت نبوی اور فقہ اسلامی کی روشنی میں ایک تحقیقی جائزہ

Education is the development of the different aspects of human being like psychological, social and physical development etc. It is not only the provision of information but it is for the sake of guidance of students to make them beneficial human beings. A teacher inculcates good habits in students and tries to reduce or terminate bad habits in them. Therefore, the responsibility of teacher is to guide the students about good and bad along with improving their academics. But while doing so, the teacher should avoid the ways which can be harmful for the students. Therefore he (the teacher) should know how to guide the students and stop them from wrong doings. At what time what technique, he should adopt that can give benefits to students? He should be aware of the student’s psychology, their age and their abilities. Sometimes punishment is very much necessary for students to make them realize not to commit anything like this again. At this critical moment what can help the student and teacher? The Holy Prophet Muhammad (SAW), being a perfect teacher guided the Umma in this aspect. He used many skills as a teacher and taught his followers, how to guide their children and pupils. Many times the prophets would use to advise his followers on anywrong doing and that is why none of the followers repeated the same mistake. It is very important to follow the teachings of the Holy Prophet in aspect. This research paper discusses the way of handling the students in different situations.

Formulation and In-Vitro In-Vivo Evaluation of Creams Containing Plants Extracts Having Skin Soothing and Depigmenting Effect

Plant extracts due to their antioxidant properties and lack of any toxicity or side effects to the human skin are becoming prevalent as ingredients in different cosmeceutical preparations because they can protect the skin from harmful ultraviolet radiations and the free radicals produced due to these radiations. Plant extracts are useful in treating different skin conditions and are effective for depigmenting and soothing effects as well as act as moisturizers when applied topically due to the different agents they contain. The current work aimed to prepare stable formulations that act as vehicle for the effective and safe delivery of active ingredients in the form of topical water-in-oil (W/O) emulsion; with comparable antioxidant properties, their in-vitro characterization and in-vivo study on human volunteers. Stable placebo formulation (F4) without active (plant extract) and stable formulations F1 (Hibiscus rosa-sinensis extract), F2 (Bombax ceiba extract) and F3 (Matricaria recutita extract) containing plant extracts were developed as creams of water-in-oil type. Antioxidant activities of plant extracts were determined by three different methods namely DPPH, reducing power activity (RPA) and nitric oxide (NO) scavenging activity while those of formulations containing plant extract were determined by DPPH (2, 2-di-phenyl-1-picrylhydrazyl) assay. Phenolic and flavonoid contents were also assessed in the extracts. In-vitro characterization was done to investigate the changes in the physical stability (color, liquefaction, phase separation, centrifugation, viscosity and rheological parameters) in active formulations (F1, F2 and F3) containing plant extract and placebo (F4) by storing them at different storage conditions, i.e. 8 ºC, 25 ºC, 40 ºC and 40 ºC + 75% RH for a span of 12 weeks. In-vivo characterization was done to measure the effects of active formulations (F1, F2 and F3) on various skin parameters like melanin, erythema, moisture contents, elasticity, sebum and surface evaluation of living skin (SELS parameters) on human volunteers by taking the reading at specific time intervals for a total of three months. For this purpose a single blinded, split face study was conducted by dividing the volunteers into three groups with 11 volunteers in each group. Statistical tools of two-way ANOVA and paired sample t-test were employed to assess the effects produced. Antioxidant activities of Hibiscus rosa-sinensis, Bombax ceiba and Matricaria recutita extracts were 78%, 90% and 87%, respectively by DPPH method. The fresh active formulations (F1, F2 and F3) containing these extracts showed 72%, 80% and 81% anti-oxidant activities, respectively while placebo formulation (F4) showed no activity. Active formulations containing plant extracts (4% each) as well as placebo F4 showed good stability and rheological characteristics for a total period of 12 weeks. Phytochemical analysis revealed that extracts are rich in phenolic and flavonoid contents. Active formulations F1, F2 and F3 exhibited significant changes in different skin parameters while placebo (F4) displayed an insignificant change in skin melanin (P=0.05), elasticity (P=0.05), and moisture contents (P=0.000) while an increase in sebum was observed. Active formulations depicted statistically significant (P=0.05) effects on surface evaluation of living skin parameters i.e., skin roughness (SEr), skin scaliness (SEsc), skin smoothness (SEsm) and skin wrinkles (SEw) while placebo formulation did not appear to affect SELS parameters significantly. On the basis of these findings, it is concluded that the formulations containing plant extracts were found safe and effective for the improvement of skin parameters. Keywords: plant extracts, W/O emulsion, rheology, stability, viscosity, melanin, erythema.