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Published: Kem. Ind. 52 (12) (2003) 573–576
Paper reference number: KUI-06/2003
Paper type: Conference paper
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Microbial Activities During Composting of Waste Microbial Biomass from the Antibiotic Production

J. Glavica, J. Friedrich and A. Pavko


Composting means the decomposition of organic matter by a mixed microbial population in a warm, moist and mostly aerobic environment. In the last decade, it has gained renewed attention as an alternative technique for treatment of solid organic wastes. Depending on the nature of organic material, the microorganisms produce varios types of enzymes, which break down components with higher molecular weight into the fragments that can be assimilated while the rest is converted into a stable product, compost. In the presented research, a waste microbial biomass, remaining after fermentation and isolation of an industrial pharmaceutical product, was treated by composting. For this reason the wet waste biomass was mixed with wood chips and the mixture was put into a 40 liter perforated plastic box. The process was followed for five days. Temperature was measured in the middle of the composting mixture. Humidity and pH of the withdrawn samples were determined, while various extracellular enzyme activities were analysed after extraction of a sample in water followed by centrifugation. Amylases, esterases and proteases were determined using a standard semiquantitative biochemical technique on solid agar plates, while cellulases and ligninases were determined quantitatively in supernatant by using spectrophotometrical methods. In the first 10 hours of composting, temperature increased from initial room temperature to a maximum of almost 60 °C, while in the next five days it slowly decreased (Fig 1). Humidity was in the range of 57 % to 51 % while pH varied between 5.6 and 8.4. Already in the innitial mixture for composting different enzyme activities were detected, some of them originating from the microbial biomass, others from the wooden structural material. During composting the following enzymes were active: proteases, esterases, cellulases, amylases, and two ligninases: laccase and manganese peroxidase (Figs. 2 and 3). In some experiments some xylanase activity was present also while lipolytic activity and lignin peroxidase activity could not be detected. The measured enzymes were extracellular, however, in the case of cellulases the activity was mostly associated to the cell membrane.

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pharmaceutical waste treatment, waste microbial biomass, composting, enzyme activities