ABSTRACT
Aims: The process parameters affecting enzyme production were optimized to ascertain the best optimal conditions for β-mannanase production by Penicillium italicum in solid state fermentation. Study Design: Four stages of experimental processes were designed for this study. The first experiment, samples were withdrawn after 24, 48, 72, 96, 120, 144,168 and 192 h incubation. In second experiment, the fermentation media were incubated at different temperatures. In third experiment, the effect of different pH values on β-mannanase production was evaluated, while the fourth experiment described the supplementation of surfactants in mineral salt solution for β-mannanase production. Place and Duration of Study: Microbiology Research Laboratory, Federal University of Technology, Akure Nigeria between September 2011 and March 2012. Methodology: β-mannanase production was conducted using Locust Bean Gum (LBG) as the sole carbon source; moisten with mineral salt solution, and enzyme activity determined by dinitrosalicylic acid method, while protein content was determined by Lowry method. Results: Maximum enzyme activity (146.389 U/ml) was observed after 72 h of incubation. Different surfactants were supplemented in the basal medium, and Sodium Dodecyl Sulfate (SDS) was observed to give the highest β-mannanase activity of 53.335 U/ml. Initial pH of the culture medium was optimized and a pH of 6.0 was found to support maximum enzyme activity (173.241 U/mg protein). The optimum incubation temperature was achieved at 35°C. Conclusion: The results obtained provide information on optimal process parameters that might improve the yield of β-mannanase by P. italicum for better fish feed formulation, especially in the larval stages of fish fingerlings when the enzyme system is not efficient.
ABSTRACT
O objetivo do estudo foi determinar, em casa de vegetação, as características estruturais de cultivares de azevém diplóides e tetraplóides, em regime de corte. Os tratamentos constaram de três cultivares diploides [Comum-RS (Lolium multiflorum), Pronto® (L. multiflorum var. westerwoldicum) e Conquest® (L. multiflorum var. italicum)]; e quatro tetraploides [INIA Titan® (L. multiflorum var. italicum), Winter Star® (L. multiflorum var. westerwoldicum), KLM 138® (L. multiflorum var. italicum) e Banquet II® (L. perenne)], alocados em delineamento completamente ao acaso com seis repetições. As cultivares foram semeadas na densidade de 10 sementes vaso-1 de 2500g de solo, com correção e fertilização realizada em dose única antes da semeadura. Quando as plantas atingiram 20 cm de altura foi realizado o primeiro corte, para dar condições ao adequado estabelecimento, enquanto os demais foram realizados quando era atingida altura média de 15 cm, deixando-se sempre resíduo de 7 cm. Por análise de variância e comparação de médias pelo teste de Tukey (P<0,05), foram analisadas as variáveis estruturais: Comprimento final da folha, número de folhas vivas por perfilho, densidade populacional de perfilhos, comprimento da planta e relação folha:colmo, avaliadas no dia de cada corte, momentos antes da execução deste. As cultivares Comum-RS, INIA Titan®, Winter Star®, Conquest®, KLM 138®, Pronto® e Banquet II® diferem quanto às características estruturais estudadas. A cultivar Banquet II® apresenta as melhores características estruturais, todavia as cultivares Winter Star®, Conquest® e KLM 138® também apresentam estrutura adequada ao pastejo durante todo seu ciclo, enquanto Pronto® e Comum-RS, ao final do ciclo, têm a acessibilidade das folhas comprometida.
The main goal was to determine, under defoliation, in greenhouse, ryegrass structural traits of diploid and tetraploid cultivars. Treatments consisted of three diploid cultivars [Comum-RS (Lolium multiflorum), Pronto® (L. multiflorum var. westerwoldicum) and Conquest® (L. multiflorum var. Italicum)], and four tetraploids [INIA Titan® (L. multiflorum var. Italicum), Winter Star® (L. multiflorum var. westerwoldicum), KLM 138® (L. multiflorum var. italicum) and Banquet II® (L. perenne)], in a completely randomized design with six replications. Cultivars were sown at a density of 10 seeds pot-1 2500g of soil; correction and fertilization was performed in a single dose before sowing. When plants reached 20 cm height the first cutting was made, to allow for appropriate establishment. The following cuttings were made when when plants reached 15 cm average height, always leaving a residue of 7 cm. Data were submitted to analysis of variance and means compared by Tukey test (P<0.05). Variables evaluated were: Final length leaf, number of life leaves, population tillers density, plant length and leaf/sheath ratio, evaluated on each cut, moments before the execution of this. Cultivars Comum-RS, INIA Titan®, Winter Star®, Conquest®, KLM 138®, Pronto® e Banquet II® differ as to structural characteristics studed. Banquet II® cultivar presents the best structural features, however the Winter Star®, Conquest® and KLM 138® cultivars also have adequate structure to grazing throughout your cycle, while Pronto® and Comum-RS, to the end of the cycle, have accessibility leaves compromised.
Subject(s)
Plants , Lolium , Crop Production , Diploidy , TetraploidyABSTRACT
Aim: The study aimed at purification and characterization of β-mannanase from Penicillium italicum. Study Design: The first experiment, β-mannanase from Penicillium italicum was produced in basal medium supplemented with Locust Bean Gum (LBG). The second described the purification of crude β-mannanase, while the third experiment dealt with characterization and kinetic studies of purified β-mannanase from Penicillium italicum. Place and Duration of Study: Microbiology Research Laboratory, Federal University of Technology, Akure Nigeria between July and August 2012. Methodology: β-mannanase from Penicillium italicum was produced in basal medium supplemented with LBG. The enzyme was purified by ammonium sulphate precipitation, ion exchange chromatography (DEAE-Sephadex A-50) and gel filtration (Sephadex G-150). The purified enzyme was characterized to determine its optimal conditions by standard assay procedures. The kinetic parameters of the purified enzyme were determined by Lineweaver-Bulk plot. Results: Fractionation of ammonium sulphate precipitated β-mannanase from Penicillium italicum on sephadex A-50 produced one major activity peak. Further fractionation of partially purified enzyme from ion exchange on Sephadex G-150 yielded one activity peak. A pH of 5.0 was optimum for purified enzyme activity and relatively stable between 40 to 100 min of incubation at this pH. The optimum temperature was 70ºC and 100% thermostable for 40 min after which a slight decline in activity was observed. The apparent Km for the hydrolysis of LBG from Lineweaver-Bulk plot was approximately 0.26 mg/mL, while the Vmax was 0.12 μmol/min/mL. The incubation of salts and organic compounds at 10 mM and 40 mM caused inhibition of enzyme activity. At 20 mM, enzyme activity was enhanced by FeSO4.7H2O, SDS and ZnSO4. 7H2O, while others caused inhibition of enzyme activity. The incubation of enzyme with CaCl2 and FeSO4.7H2O at 60 mM enhanced enzyme activity, while others caused inhibition. Conclusion: The result obtained from this study revealed that purified β-mannanase is active over a wide pH and temperature, and its stability implies that the enzyme will be useful during industrial processes where extreme conditions are required.