Fungal and enzymatic treatment of mature municipal landfill leachate.

The aim of our study was to evaluate biotreatability of mature municipal landfill leachate by using white rot fungus and its extracellular enzymes. Leachates were collected in one active and one closed regional municipal landfill. Both chosen landfills were operating for many years and the leachates generated there were polluted by organic and inorganic compounds.

Optimization of ligninolytic enzyme activity and production rate with Ceriporiopsis subvermispora for application in bioremediation by varying submerged media composition and growth immobilization support.

Response surface methodology (central composite design of experiments) was employed to simultaneously optimize enzyme production and productivities of two ligninolytic enzymes produced by Ceriporiopsis subvermispora. Concentrations of glucose, ammonium tartrate and Polysorbate 80 were varied to establish the optimal composition of liquid media (OLM), where the highest experimentally obtained activities and productivities were 41 U L(-1) and 16 U L(-1) day(-1) for laccase (Lac), and 193 U L(-1) and 80 U L(-1) day(-1) for manganese peroxidase (MnP). Considering culture growth in OLM on various types of immobilization support, the best results were obtained with 1 cm beech wood cubes (BWCM).

The use of the fungus Dichomitus squalens for degradation in rotating biological contactor conditions.

Biodegradation potential of Dichomitus squalens in biofilm cultures and rotating biological contactor (RBC) was investigated. The fungus formed thick biofilms on inert and lignocellulosic supports and exhibited stable activities of laccase and manganese peroxidase to reach 40-62 and 25-32% decolorization of anthraquinone Remazol Brilliant Blue R and heterocyclic phthalocyanine dyes, respectively. The decolorization ceased when glucose concentration dropped to 1 mmol l(-1).

Enhanced enzyme production with the pelleted form of D. squalens in laboratory bioreactors using added natural lignin inducer.

White-rot fungi are extensively used in various submerged biotechnology processes to produce ligninolytic enzymes. Transfer of the process from the laboratory to the industrial level requires optimization of the cultivation conditions on the laboratory scale. An interesting area of optimization is pellet growth since this morphological form solves problems such as the decreased oxygen concentration, limited heat, and nutrient transport, which usually occur in dispersed mycelium cultures.

Oxygen transfer in a laboratory stirred tank bioreactor during Mammalian cell culture cultivation.

The influence of power consumption on the volumetric mass transfer coefficient was studied in a 5 liter stirred tank bioreactor during cultivation of a recombinant Chinese Hamster Ovary (CHO) cell line, which requires low aeration and mixing intensity. Under these conditions and at high cell concentrations, oxygen mass transfer coefficient and consequently volumetric oxygen mass transfer rate was not sufficient for the oxygen requirements. This problem was successfully solved by introducing pure oxygen into the bioreactor and the oxygen mass balance was studied.

Constitutive versus thermoinducible expression of heterologous proteins in Escherichia coli based on strong PR,PL promoters from phage lambda.

Constitutive and thermoinducible expression plasmids based on strong P(R),P(L) promoters from phage lambda were compared for production of TNF-alpha and its analogs under various conditions. Much higher accumulation of TNF was obtained in a constitutive system, so the wider applicability of such systems was studied. In constitutive systems, proteolytically susceptible proteins can be produced easily at low cultivation temperatures and the addition of expensive or toxic chemical inducers is not required.