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ABSTRACTFilamentous fungi are widely used for the production of homologous and heterologous proteins. Recently, there has been increasing interest in Aspergillus oryzae PP and Aspergillus awamori K-1 because of its ability to produce heterologous proteins in submerged (liquid) cultures. The goal of this investigation was to determine the α-amylase and endoxylanase enzyme production ability and molecular characteristics of fungal strains Aspergillus oryzae PP and Aspergillus awamori K-1 and its mutant strains R5 and A45. The strains were cultivated in liquid culture and maximum enzyme production of parent and mutant strains was determined after 72–96 h of cultivation. Extracellulars α-amylase and endoxylanase were partially purified from the culture filtrates, using molecular sieve chromatography with Gel permeation chromatography. The molecular weight of the partial purified enzymes has been estimated to be 57 kDa for α-amylase and 31 kDa for endoxylanase on SDS-polyacrylamide gel electrophoresis. The temperature optimum of the enzyme α-amylase was 30°C, respectively for endoxylanase was 40°C and the pH optimum was 4.7 and 4.0.

ABSTRACTMus spicilegus is an outdoor species from southern-eastern Europe, adapted to agroecosystems. In the beginning of autumn, to spend the winter, mound-building mice build complex mounds. These mounds are built using accumulation of seeds covered with earth. This behavior is unique among mice species. However, there is evidence that at higher temperatures and a larger availability of food in winter, mice can optimize this particular behavior in direction to simpler constructions or even not build them at all. To clarify if mice display building activity under laboratory conditions we studied behavior of M. spicilegus in 5 intraspecific cage groups during autumn-winter period. The observations were carried out in 100 × 100 cm glass cages provided with earth and sawdust as bedding and straw and hay as nesting material. The groups were formed by 3–4 mice captured from a wild population in northern Bulgaria in early September of 2008, where mounds were already built. Mice were grouped according to the mound they belong to. The results showed that mound-building mice display high level of building activity, especially in the first month of their time in the laboratory. In majority of groups mice built domed nests made from straw and hay, where they lived together. Seeds in the cages were covered with earth, as far as that was possible. However, mice in some groups made burrows of simple design. Based on these findings it could be assumed that building behavior of M. spicilegus is genetically determined, but as microtine rodents M. spicilegus can be quite flexible in employing behavior to suit the local environment.

ABSTRACTDifferent aspects, including safety, functional and technological characteristics, have to be taken into consideration in the selection of each probiotic microorganism. The aim of the present work was to determine the kinetic growth parameters of L. plantarum strain after cultivation in media with different carbon sources. The strain was isolated from traditional Bulgarian white cheese and previously characterized as putative probiotic, based on commonly accepted in vitro criteria. For further biotechnological implementation was necessary to select a suitable and economically relevant growth media. Thus, reconstituted permeate (6% w/v) and the following modification of de Man, Rogose Sharpe media (MRS): (i) MRS-glucose; (ii) MRS-lactose; (iii) MRS-galactooligosaccharide; (iv) MRS-fructooligosaccharide were used. The strain growth, lactic acid production and carbon source utilization were monitored by pH and cell number determination, and HPLC analysis at different time points of the cultivation process. The highest cell growth and carbohydrate conversation were detected in the presence of glucose and lactose. The main product of the fermentation was lactate with detectable level of acetate. The permeate and MRS-galactooligosaccharide also support good growth and lactic acid production, which indicate a great potential for industrial applications of studied L. plantarum strain into the food system.

ABSTRACTIn recent years interest in the probiotic lactobacilli has been stimulated by the use of these bacteria in products that are claimed to confer health benefits on the consumer. The probiotic effects are usually strain-specific, meaning that a correct identification is important to link the strain to the specific health effect. Taxonomical characterization of probiotic strains only in phenotypic and phisyological characteristics is often with low level of discrimination, probably due to their co-evolution in the same ecological niches. Thus, the nucleotide base techniques provide an accurate basis for phylogenetic analysis and identification. With this aim a probiotic strain Lactobacillus spp. 50P1 was studied.Trough the physiological characterization with API 50 CH the strain 50P1, was determinate as Lactobacillus helveticus, with low probability- 77,5%. Three PCR-based methods, species-specific PCR, of 16S rRNA gene sequencing, and restriction enzyme of 16S rDNA ARDRA analysis were used for reliable taxonomic characterization of probiotic strain Lactobacillus sp. 50P1. The sequence obtained from the strain was compared to those of Lactobacillus species held in GenBank and the belonging of the strain 50P1 to the species Lactobacillus helveticus was confirmed.