Utilización de dos soportes para la inmovilización de la papaína

Papain was immobilized on activated carbon (AC) and on alumina (AL), with the aim of preparing low cost dietarysupplements, using whey as hydrolysed protein source. The quantifi cation of the non-adsorbed enzyme, using Lowry’smethod was used to determine the immobilization rate. The effect of the contact time and the temperature was tested,and 30 min at 250C was considered the best condition for immobilizing papain in both supports. AC showed muchhigher immobilization rates (from 95% to 99%) than AL (from 4% to 13%). The reusability of papain was evaluated bymeasuring the residual activity of the enzyme after it has been used for up to 20 times. The quantifi cation of exposurerate of phenylalanine by second derivative spectrophotometry was used to determine the enzyme activity. In this case, ALshowed better results than AC, since the activity of papain remained unchanged after 15 and 5 times, respectively.Con la intención de preparar suplementos dietéticos de bajo coste, se inmovilizó papaína en carbón activado (CA) yen alúmina, utilizando suero como fuente de proteínas hidrolizadas. Para determinar el índice de inmovilización secuantifi caron las enzimas no adsorbidas mediante el método de Lowry. Se analizó el efecto del tiempo de contactoy la temperatura, considerándose 30 min. a 25 ºC como la condición óptima para inmovilizar la papaína en ambossoportes. El CA presentó unos índices de inmovilización muy superiores (entre 95% y 99%) a los de la AL (entre4% y 13%). Para evaluar la capacidad de reutilización de la papaína se midió la actividad residual de la enzimadespués de haber sido utilizada hasta 20 veces. Para determinar la actividad de la enzima se cuantifi có el índice deexposición de la fenilalanina mediante espectrofotometría de derivada segunda. En este caso, la AL presentó mejoresresultados que el CA, ya que la actividad de la papaína seguía siendo la misma después de haber sido utilizada 15y 5 veces, respectivamente

Parallel use of shake flask and microtiter plate online measuring devices (RAMOS and BioLector) reduces the number of experiments in laboratory-scale stirred tank bioreactors

Background Conventional experiments in small scale are often performed in a Black Box fashion, analyzing only the product concentration in the final sample. Online monitoring of relevant process characteristics and parameters such as substrate limitation, product inhibition and oxygen supply is lacking. Therefore, fully equipped laboratory-scale stirred tank bioreactors are hitherto required for detailed studies of new microbial systems. However, they are too spacious, laborious and expensive to be operated in larger number in parallel. Thus, the aim of this study is to present a new experimental approach to obtain dense quantitative process information by parallel use of two small-scale culture systems with online monitoring capabilities: Respiration Activity MOnitoring System (RAMOS) and the BioLector device. Results The same mastermix (medium plus microorganisms) was distributed to the different small-scale culture systems: 1) RAMOS device; 2) 48-well microtiter plate for BioLector device; and 3) separate shake flasks or microtiter plates for offline sampling. By adjusting the same maximum oxygen transfer capacity (OTRmax), the results from the RAMOS and BioLector online monitoring systems supplemented each other very well for all studied microbial systems (E. coli, G. oxydans, K. lactis) and culture conditions (oxygen limitation, diauxic growth, auto-induction, buffer effects). Conclusions The parallel use of RAMOS and BioLector devices is a suitable and fast approach to gain comprehensive quantitative data about growth and production behavior of the evaluated microorganisms. These acquired data largely reduce the necessary number of experiments in laboratory-scale stirred tank bioreactors for basic process development. Thus, much more quantitative information is obtained in parallel in shorter time.Cluster of Excellence “Tailor-Made Fuels from Biomass”, which is funded by the Excellence Initiative by the German federal and state governments to promote science and research at German universities