Continuous production of glucose oxidase with Aspergillus sp. under ultrasound waves

Application of low-strength ultrasonication to the continuous anaerobic digestion processes: UASBr and dry digester

In this study, the positive effects of low-strength ultrasonication (LS-ultrasonication) on the anaerobic digestion (AD) performance were investigated by continuously operating an upflow anaerobic sludge blanket reactor (UASBr) and a dry digester. In the ultrasonicated UASBr system (1 s per min, 0.05 W/mL), ultrasonication enhanced the CH₄ production by 38% and 19% in an ambient and a mesophilic condition, respectively. In addition, a different sludge yield and a changed electron flow were observed after ultrasonication. In the ultrasonicated dry digestion system (2 s per 30 s, 0.0025 W/mL), a 40% increase in the production of CH₄ was observed after lowering the total solid content of the reactor from 12% to 10%, implying that a high solid content diminished the ultrasonic stimulation effect. Moreover, the ultrasonication strength itself appeared to be a more crucial factor than the ultrasonication density during the application of LS-ultrasonication in the AD system.

Studies on the lipolytic activity of sonicated enzymes from Yarrowia lipolytica

The aim of this study was to evaluate the efficiency of sonication in releasing protein from a widespread lipase-producing yeast, Yarrowia lipolytica KKP 379, and to examine the impact of ultrasound waves generated in a horn-type sonicator on the lipolytic activity of Y. lipolytica in the hydrolysis of p-nitrophenyl laurate. In this paper, we focused on a few parameters of ultrasound cell disruption, such as the time of sonication, acoustic power, storage time of the frozen yeast biomass used in sonication and the solvent used to suspend the yeast cells which were considered as the most important part in the process of obtaining a biocatalyst from Y. lipolytica for organic synthesis. The most effective additive in protein release proved to be 2% Tween 80; other ideal parameters of the process were ultrasonic power at 150 W for 15 min and 9 weeks of frozen biomass storage time. The sonication parameters, which were the best for protein release, did not seem to be the most effective for obtaining high lipolytic activity due to denaturation as an effect of cavitation.

A combination of ultrasound and oxidative enzyme: sono-biodegradation of substituted phenols

Sonolysis, enzyme treatment, and a combination of the two processes were tested for the degradation of substituted phenols (phenol, p-chlorophenol, p-bromophenol, p-iodophenol, p-methoxyphenol, p-cresol and p-nitrophenol) in aqueous medium. These organic pollutants are divided into three groups according to their degradation behaviour. In group (I), p-nitrophenol, horseradish peroxidase (HRP) in presence of hydrogen peroxide had a negligible effect on its decomposition. The combined method showed the same effect as sonolysis. Therefore, it is convenient to degrade p-nitrophenol by ultrasonic waves alone. In group (II), p-methoxyphenol and p-cresol, the combined method was approximately the same as enzyme treatment. It means that, the ultrasound had a negligible effect and the enzyme treatment alone was more favourable. Phenol and its halogenated compounds (choloro, bromo and iodo) were placed in group (III) and showed different behaviour than the two mentioned cases. The combined method was more efficient than the sonolysis and enzyme treatment individually. It should be noted that the effect of enzyme on this group (III) was in the medium level in compare of the two other groups (I and II) which the enzyme had a lower and higher effects respectively.