Open Access Original Research Article

Increase in Endoglucanase Productivity and Mycelial Stability of Rhizopus oryzae by Classical Mutagenesis

Sudarshana Bandyopadhyay, Moumita Karmakar, Rina Rani Ray

Biotechnology Journal International, Page 60-72
DOI: 10.9734/BBJ/2012/1037

Aim: To develop a mutant strain with high endoglucanase productivity and optimization of some cultivation parameters.
Place and Duration of Study: Microbiology Research Laboratory, Department of Zoology, Molecular Biology & Genetics, Presidency University, College Street, Kolkata: 700 073, India, between Aug, 2010 and March 2011.
Methodology: The wild strain of Rhizopus oryzae PR7 MTCC 9642 was subjected to classical mutagenesis by suspending 5 hyphal discs (0.5 cm) in 10ml of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) solutions of various concentrations (125-1000µg). The in situ cellulolytic activity of the colonies of the mutant strains on the plates were measured by using alcoholic iodine solution and the highest enzyme producing mutant was selected. The mutant strain was later cultivated in presence of various domestic wastes at various pH, temperature, time. The morphological alteration was also checked by staining with fluorescent dye.
Results: Out of 50 mutants, strain A7 was selected that showed about 33% increase in endoglucanase synthesis utilizing orange bagasse as sole carbon source in a shake flask screen. The strain was found to have the same pH and temperature optima, but could achieve highest level of enzyme production earlier than that by its wild counterpart. Being a dimorphic fungus, the wild type strain of Rhizopus oryzae, showed a transformation to yeast like pelleted form, whereas the mutant strain A 7 showed persistent filamentous structure indicating the achievement of a structural stability in presence of environmental stress.
Conclusion: The present mutant strain could ferment orange bagasse and showed an increased production of endoglucanase with minimized time consumption with greater mycelial stability against various environmental stresses. These achievements will definitely add economy in industrial production of endoglucanse at a nominal cost.

Open Access Original Research Article

Biosorption of Lead by Bacillus cereus Isolated from Industrial Effluents

Shruti Murthy, Geetha Bali, S. K. Sarangi

Biotechnology Journal International, Page 73-84
DOI: 10.9734/BBJ/2012/1173

Aims: To study the biosorption of lead ions from solution using Bacillus cereus isolated from industrial effluents collected from Peenya industrial area, Bangalore, India and to determine the optimum conditions for biosorption.
Study Design: Experimental study.
Place and Duration of Study: Department of Microbiology and Biotechnology, Bangalore University, Bangalore, Karnataka, India, between October 2008 and December 2009.
Methodology: Sixty bacterial strains were isolated from industrial effluents collected from Peenya industrial area. Among the sixty isolates only six were selected for further investigation due to their high minimum inhibition concentration for lead. Lead biosorption studies were carried out for all the six isolates using atomic absorption spectrometry. The optimum conditions (temperature, pH and culture age) for biosorption were determined for the isolate showing highest lead biosorption.
Results: The lead biosorption capability of all six isolates was studied at different concentrations of lead (100, 200, 300, 400 and 500 mg/l). The isolate 6 showed highest lead biosorption capability and was identified as Bacillus cereus. Studies on the control of environmental factors revealed that an optimum temperature of 30°C and pH 5, facilitates maximum biosorption of lead by 24hrs old culture of Bacillus cereus.
Conclusion: Biosorption is an alternative to traditional physicochemical methods for removing toxic metals from wastewaters. The results of this study are discussed in the light of the biosorption capacity of Bacillus cereus that could be exploited in the bioremediation of lead.

Open Access Original Research Article

Adsorption and Stabilization of a Raw Starch Digesting Amylase on Micro Bead Silica Gel 300 A

Tochukwu Nwamaka Nwagu, Hideki Aoyagi, Bartholomew N. Okolo

Biotechnology Journal International, Page 85-101
DOI: 10.9734/BBJ/2012/894

Aims: To produce a robust starch hydrolyzing enzyme (improved catalytic and non-catalytic properties) by the adsorption of the soluble enzyme on micro bead silica gel.
Place and Duration of Study: Department of Life Sciences and Bioengineering, Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba-shi Ibaraki-ken, Japan between July 2009 and August 2010.
Methodology: Ten types of Micro Bead silica gel with pore sizes ranging from 0.4-100 nm were screened to determine the best support for the immobilization of a microbial raw starch digesting amylase (RSDA). The micro bead which gave the highest yield was selected for further studies. Properties of the immobilized enzyme were compared to the free type to determine the effect of immobilization on catalytic, storage and operational stability.
Results: Micro Bead 300 A gave the highest yield and the optimum condition for adsorption of the RSDA was at pH 5, 25°C for 24 h. Optimum pH of the immobilized enzyme shifted from 5 to 4.5 and optimum temperature from 30 to 50°C. The immobilized amylase retained over 70% of its initial activity after 12 h incubation at 70°C in 0.2 M citrate phosphate buffer pH 5 whereas free enzyme lost 92% initial activity under same conditions. Immobilized enzyme retained 95% activity after 10 batch reactions of 30 min each and 100% activity after storage for 6 weeks at room temperature.
Conclusion: Immobilized RSDA was marginally more pH and temperature stable compared to the native type. It also exhibited storage stability and could be re-used repeatedly without considerable desorption during washing. The kinetic and stability features combined with the properties of the support make this process appealing for industrial application.

Open Access Original Research Article

Screening Maize (Zea mays L.) Genotypes by Genetic Variability of Vegetative and Yield Traits Using Compromise Programming Technique

Atif Elsadig Idris, Hassan Ibrahim Mohammed

Biotechnology Journal International, Page 102-114
DOI: 10.9734/BBJ/2012/1292

The present study was made to develop a suitable procedure for selecting the most sustainable maize genotype to grow by considering genetic variability for vegetative, yield and yield components under irrigated farming. The experiment was conducted at the experimental farm, College of Agricultural studies, Sudan University of Science and Technology, Shambat, during summer seasons of 2007/08 and 2008/09, respectively. Significant variability was observed for plant height, stem diameter, number of rows per cob and ear length during the first season 2007/08 and for days to 50% flowering and 100-seed weight during the second season 2008/09. Frantic genotype scored maximum seed weight (81.0g) while Baladi had least seed weight (57.48g). Frantic genotype had maximum grain yield (0.577 ton/ha), while minimum grain yield ton/ha was recorded in Baladi (0.473 ton/ha). Data recorded for heritability showed that days to 50% flowering had maximum heritability (79.1%) while the minimum heritability (4.46%) was recorded for 100 seed weight. The present study revealed considerable amount of diversity among the tested populations which could be manipulated for further improvement in maize breeding in Sudan. However, significant differences of grain yield were observed among varieties. Due to the observed variability multi objective compromise programming technique is employed to screen these Maize (Zea mays L.) genotypes according to their vegetative and yield traits for purpose of selecting the best one that suit irrigated farming conditions of Shambat area. The study ranked the different Maize (Zea mays L.) genotypes and recommends the best alternative. Ranking of alternatives was explored in reference to selection criteria weights preferred by an agronomist, animal production specialist and nutrition scientist in comparison to equal weights.