Advanced Journal of Microbiology Research

Advanced Journal of Microbiology Research Vol. 2005

Available online at http://internationalscholarsjournals.org/journal/ajmr

© 2005 International Scholars Journals

Full Length Research Paper

Production and partial characterization of a thermostable amylase from ascomycetes yeast strain isolated from starchy soils

Bertrand Tatsinkou Fossi¹, Frédéric Tavea¹, Robert Ndjouenkeu^1*

Department of Food Science and Nutrition, University of Ngaoundéré, P.O.Box 455 Ngaoundéré, Cameroon.

Accepted 14 july, 2004

Abstract

An amylolytic yeast strain was isolated from starchy soils (flour mills environment, flour market, cassava farms after harvesting and transformation of tubers) and its enzyme productivity and activity evaluated. The enzyme synthesis was optimum at 30°C when initial pH of fermentation medium was 4.5. After extraction and partial purification, the enzyme remained stable in a range of temperature and pH between 20°C-60°C and 2-8 pH respectively. The optimum enzyme activity was displayed at 70°C and pH 5.5 and 6.5. The thermostability of the enzyme was comparable to that of amylases from bacteria.

Key word: Amylolytic yeast, amylase activity, thermostable amylase.

Advanced Journal of Microbiology Research Vol. 2004

Available online at http://internationalscholarsjournals.org/journal/ajmr

© 2004 International Scholars Journals

Full Length Research Paper

Histological exploration of follicular population of the Moroccan bovine (Oulmes-Zaers) breed

A. Fassi Fihri¹, K.H. Hajji¹ and H. Lakhdissi²

¹Laboratory of Zoology and General Biology, Department of Biology, College of Science, University Mohamed V. Rabat, Morocco.

²Department of Animal Reproduction, Obstetrics and Artificial Insemination. Hassan II Agronomy and veterinary Medicine Institute, Rabat, Morocco.

Accepted 27 April, 2004

Abstract

Follicular population and repartition in the ovarian cortex was investigated in the ovaries of the Oulmès-Zaers cattle breed and its crosses. A total of 30 ovaries were collected at slaughterhouse in Casablanca and Rabat from Oulmes-Zaers breed and its crosses (2 genotypes) of 3 age groups (<3; 3 to 5; >5 years). The histological study of the ovary revealed that the ovarian cortex is composed of different areas (from the periphery to the medulla), the non stratified epithelium of the ovary, the tunica albuginea composed of two areas rich of collagen fibers directed into different ways white variable thickness. The primordial and antral follicles appear in underlying areas. Therefore, the follicles cannot appear on the ovarian surface when situated under thicker Layers. At the quantitative level, the ovary of the Oulmes-Zaears breed seems to contain less follicles in animals less than 3 years of age as compared to the crossbreed (P< 0.05). Between 3 and 5 years of age, the follicles occupied similar areas of the ovaries (17% and 18% for oulmes-Zaers and its crosses, respectively). This study shows that the ovary of the Moroccan local cattle breed (Oulmes-Zaers) is equipped with a whole plain follicular population that is more important than the one visible on the surface of the ovary and which is exploited by aspiration and picking techniques.

Key words: Ovary, Oulmès-Zaers, follicular population, bovine, age.

Advanced Journal of Microbiology Research Vol. 2004

Available online at http://internationalscholarsjournals.org/journal/ajmr

© 2004 International Scholars Journals

Full Length Research Paper

Optimization of industrial production of rifamycin B by Amycolatopsis mediterranei. II. The role of gene amplification and physiological factors in productivity in shake flasks

El-Tayeb, O.M.¹*, Hussein, M. M. M.², Salama, A.A.² and El-Sedawy, H.F.¹

¹Microbial Biotechnology Center, Faculty of Pharmacy, Cairo University, Cairo, Egypt.

²Department of Microbiology and Immunology, Faculty of Pharmacy, Cairo University, Cairo, Egypt.

Accepted 25 March 2004

Abstract

Amplification of gene expression of the most productive colony type of Amycolatopsis mediterranei strain N1 under stress of chloramphenicol, resulted in isolation of a variant NCH with productivity of 2.56 g/l compared to 1.15 g/l by the parent strain N1 (2.2 fold increase) . This amplified variant has a further advantage of reduced variation in colony morphology with predominance of the most productive colony type. Using variant NCH, modification of the fermentation medium F1 by the addition of 0.1% yeast extract or the use of 1.8% KNO₃ resulted in 3.8 and 5.8-fold increase in productivity, respectively, compared to strain N1. When the F1 medium was replaced by a new medium F2 containing soytone, instead of the particulate constituents (peanut meal and soybean meal) the yield by variant NCH reached 7.85 g/l (6.8-fold increase). Modification of the F2 medium by addition of glycerol or the replacement of glucose by glucose syrup decreased rifamycin B production. Changing the concentration of soytone increased the yield only slightly while replacing it with peptone or tryptone or the addition of 1 % corn steep liquor failed to increase the yield. On the other hand, the addition of 0.1 %  yeast extract, or the replacement of 0.6% (NH₄)₂SO₄ by 1.2% KNO₃ or 0.4% NH₄NO_3, to F2 medium led to 8.2, 10.2 and 10.4-fold increase in productivity, respectively, compared to productivity of strain N1 in F1 medium. The change in the concentrations of either MgSO₄ or CaCO₃, the use of different types of antifoams and the use of higher concentrations of sodium diethyl barbiturate did not significantly influence the yield. These collective optimization attempts thus resulted in a 10.4-fold increase in productivity, from 1.15 to 11.99 g/l.

Key words: Rifamycin B, fermentation, biotechnology, Amycolatopsis mediterranei, optimization, gene amplification, physiological factors.

Advanced Journal of Microbiology Research Vol. 2004

Available online at http://internationalscholarsjournals.org/journal/ajmr

© 2004 International Scholars Journals

Full Length Research Paper

Optimization of industrial production of rifamycin B by Amycolatopsis mediterranei. I. The role of colony morphology and nitrogen sources in productivity

El-Tayeb, O.M.¹*, Salama, A.A.², Hussein, M.M.M.² and El-Sedawy, H.F.¹

¹Microbial Biotechnology Center, Faculty of Pharmacy, Cairo University, Cairo, Egypt.

²Department of Microbiology and Immunology, Faculty of Pharmacy, Cairo University, Cairo, Egypt.

Accepted 24 March 2004

Abstract

A systematic approach to process optimization for production of rifamycin B was applied to a strain of Amycolatopsis mediterranei. Examination of the growth revealed 6 different morphologically distinct colonies on Bennett’s agar medium. Rifamycin B production in shake flasks by the six different colony types ranged between 0.5 and 1.2 g/l. There was a clear correlation between the colony morphology and rifamycin B productivity. The highest yield of rifamycin B (1.03-1.2 g/l) was obtained by using the orange-red colored colonies, rosette shaped, devoid of hollow center and 2-3 mm in diameter. Variability in colony morphology, however, remained and the appropriate colonies had to be picked up for preparing the inoculum of each experiment. Addition of yeast extract to the fermentation medium at different times increased rifamycin B production. The highest antibiotic production was obtained upon the addition of 0.1% yeast extract after 2 days of incubation, where the yield increased from 1.15 to 1.95 g/l (70%). The use of 1.8% KNO₃ in the fermentation medium, instead of 0.96% (NH ₄)₂SO_4, markedly increased rifamycin B production from 1.15 to 2.92 g/l (154%). It was also observed, upon microscopical examination, that KNO₃ decreased branching and fragmentation of the mycelia in the fermentation medium.

Key words: Rifamycin B, fermentation, biotechnology, Amycolatopsis mediterranei, strain selection.

Advanced Journal of Microbiology Research Vol. 2004

Available online at http://internationalscholarsjournals.org/journal/ajmr

© 2004 International Scholars Journals 

Full Length Research Paper

Improving bambara groundnut productivity using gamma irradiation and in vitro techniques

H.K. Adu-Dapaah¹* and R.S. Sangwan²

¹Crops Research Institute, P. O. Box 3785, Kumasi, Ghana.

²Director, Androgenesis and Biotechnology Laboratory, Université de Picardie Jules Verne, 33 rue Saint Leu, F-80039 Amiens, France

Accepted 29 March, 2004

Abstract

In recent times efforts are being made to improve the productivity of bambara groundnut. Studies were initiated (i) to characterise and evaluate landraces and to select superior ones for irradiation, (ii) to induce genetic variation through gamma irradiation and (iii) to use biotechnological approaches to shorten the generation cycle. The results of the study indicated that gamma irradiation induced higher genetic variation of up to four times within the varieties used in the study compared to the unirradiated control. Bambara groundnut yield could be increased through selection for number of pods per plant. Using the in vitro plus in vivo system and embryo axis explants, over four generations per year were obtained compared to 1 or 2 in the field. All the plants were morphologically normal and fertile. The shorter duration, high efficiency and genotype independency makes this system well suited for wider biotechnological applications in bambara groundnut. This novel approach is being applied to the variants/mutants obtained from gamma irradiation.

Key words: Gamma irradiation, generation cycle, genetic variation, Vigna subterranean.

Advanced Journal of Microbiology Research Vol. 2004

Available online at http://internationalscholarsjournals.org/journal/ajmr

© 2004 International Scholars Journals

Full Length Research Paper

High frequency plant regeneration from desiccated calli of indica rice (Oryza Sativa l.)

Vinod Saharan¹*, Ram C. Yadav², Neelam R. Yadav², Bishnu P. Chapagain¹

¹The Institutes for Applied Research, Ben-Gurion University, P.O.B. 653, Beer-Sheva 84105, Israel.

²Department of Biotechnology and Molecular Biology, CCS HAU, Hisar 125004 (Haryana), India.

Accepted 27 March, 2004

Abstract

An efficient and reproducible protocol is required to achieve high frequency transformation from transformed calli. We report here high frequency plant regeneration from mature seed derived embryogenic calli of two recalcitrant indica rice cultivars HKR-46 and HKR-126 after partial desiccation treatment. Embryogenic and nodular callus was initiated on MS basal medium supplemented with 2.5 mg l^-1 2,4-D, 500 mg l^-1 proline, 500 mg l^-1 casein hydrolysate, 30 g l^-1 sucrose and 2.5 g l^-1 gelrite. Several media with different combinations of growth regulators were tried. Maximum shoot regeneration frequency (63%) was observed in partially desiccated calli for 48 h in cv. HKR 46 and 82.1 per cent in cv. HKR-126 on the MS modified medium supplemented with 2 mg l^-1 kinetin + 0.5 mg l^-1 NAA + 30 gl^-1 sucrose + 6 g l^-1 gelrite followed by in the medium supplemented with 1 mgl^-1 2ip + 30 g l^-1 sucrose + 6 g l^-1 gelrite (61% in cv. HKR-46 and 79.2 % in cv. HKR-126). Highly significant regeneration differences were observed in partially desiccated calli (48 h) in comparison to non-dehydrated (0 h desiccation) calli. Shoot regeneration frequency increased from 1.2 to 5.6 fold after 48 h of desiccation in both the cultivars on different regeneration media. Shoot regeneration frequency declined at 72 h desiccation treatment as compared to 48 h treatment. Well-developed plantlets were hardened and transferred to the green house.

Key words: Plant regeneration, indica rice, mature embryo, partial desiccation.