ObjectiveThis work is the first application of a morphological engineering technique called microparticle-enhanced cultivation (MPEC) aimed at the facilitation of laccase production in the submerged cultures by two basidiomycetes species Cerrena unicolor and Pleurotus sapidus.ResultsThe positive effect of the applied 10 μm Al2O3 microparticles at concentrations from 5 to 30 g Al2O3 l−1 was shown. Laccase activity increased 3.5-fold for C. unicolor and 2-fold for P. sapidus at 15 g Al2O3 l−1 on 9 and 14 day of the cultivation, respectively, compared to the control culture without microparticles. The increase of laccase activity in the cultivation broths was caused by the action of Al2O3 microparticles on the agglomeration of hyphae. It led to the decrease of the size of the pellets, (on average by 2 mm for C. unicolor), the change of their shape (star-shaped pellets for C. unicolor) and the change of their structure (more compact pellets for P. sapidus).ConclusionsApplication of MPEC for the submerged cultures of two laccase-producing basidiomycetes proved successful in increasing of enzyme production.

Morphological engineering techniques have recently gained popularity as they are used for increasing the productivity of a variety of metabolites and enzymes in fungi growing in submerged cultures. Their action is mainly associated with the changes they evoke in fungal morphology. Traditional morphological engineering approaches include manipulation of spore concentration, pH-shifting and mechanical stress exerted by stirring and aeration. As the traditional methods proved to be insufficient, modern techniques such as changes of medium osmolality or addition of mineral microparticles to the media (microparticle-enhanced cultivation, MPEC) were proposed. Despite the fact that this area of knowledge is still being developed, there are a fair amount of scientific articles concerning the cultivations of filamentous fungi with the use of these techniques. It was described that in Ascomycetes fungi both MPEC or change of osmolality successfully led to the change of mycelial morphology, which appeared to be favorable for increased productivity of secondary metabolites and enzymes. There are also limited but very promising reports involving the successful application of MPEC with Basidiomycetes species. Despite the fact that the mineral microparticles behave differently for various microorganisms, being strain and particle specific, the low cost of its application is a great benefit. This paper reviews the application of the modern morphology engineering techniques. The authors critically assess the advantages, shortcomings, and future prospects of their application in the cultivation of fungi.

Gasification of char derived from sewage sludge was studied under different oxidizing atmospheres containing CO 2 , O 2 or H 2 O. The gasification tests were carried out in thermobalance at different temperatures and oxidizing reagent concentrations. The most efficient were the gaseous mixtures containing oxygen. The reaction took place at temperature 400-500°C, whilst in the case of CO 2 and steam much higher temperatures (700-900°C) were necessary to complete the conversion. Two rate models for gas-solid reaction were applied to describe the effect of char conversion on reaction rate. The shrinking core model for reaction-controlled regime was found to be the best for predicting the rate of char gasification in CO 2 and O 2 atmosphere. The experimental data for steam gasification of the char were fitted best by the first-order kinetics. The kinetic parameters estimated from the experimental data are in accordance with the literature for lignocellulosic char gasification and are the first published for sewage sludge char gasification.

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