Acta Microbiologica Bulgarica

10-25

Authors: Kroumov, A. D., Módenes, A. N.

The objective of this review article was to highlight the authors’ more than 30 years’ experience in the field of model development procedure of ethanol biosynthesis. During all these years a powerful system analysis theory and its decomposition principles were applied not only for studying and description of microbial kinetics but for the needs of bioprocesses and bioreactors/photobioreactors optimization and scale-up. Special attention was given to the description of phenomena and techniques involved in ethanol synthesis on single and two substrates utilization processes by wild and genetically modified strains. The method of simultaneous saccharification and fermentation of starch to ethanol (SSFSE) by genetically modified microbial Saccharomyces cerevisiae YPB-G strain is presented to fully illustrate the strength of the applied theory. Another modern method for extractive fermentation and ethanol production is presented as well. Diauxic growth phenomena in ethanol synthesis is the example showing a modeling approach by connecting knowledge from molecular and population hierarchic levels. This modeling work helped tremendously to find new insights on the control of internal metabolic mechanisms of the cells and how the processes can be guided to an optimal trajectory. A parameter identification procedure was performed by using the latest achievements in global search methods. The applied strategy of model development was extremely successful in obtaining new knowledge about the microbial systems’ behavior as well as for fast and robust bioprocesses development. The review article can be very useful for modelers and young scientists working in the fields of biotechnology, bioengineering, metabolic and chemical engineering.

42-46

Authors: Bumbarov, V., Tzymanis, A., Hristov, M., Peshev, R., Eligulashvili, R.

An immunohistochemistry method on frozen tissue cryostat sections based on new polyclonal monospecific affinity-purified rabbit antibodies (PMAP) against 19-residue synthetic peptides (154-171), originated from the group-specific peptide P-32 for sheep poxvirus (SPV) was developed. PMAP were used as primary antibodies in an immunohistochemistry test on frozen ovine tissue for rapid laboratory diagnosis of SPV infection. This method is highly specific, reproducible, simple and inexpensive. The total time of the procedure was within 2 hours of receiving the samples in the laboratory.

56-64

Authors: Atanasova-Pancevska, N., Popovska, I., Davalieva, K., Kungulovski, D.

New antimicrobial compounds are continuously required to combat antibiotic-resistant bacteria and pathogenic yeast as such resistance increasingly limits the effectiveness of current antimicrobial drugs. New screening approaches, including the search for novel targets and exploration of non-conventional places as sources of producer microorganisms, are needed. Rotten apples compost samples from the composting plant in Resen, Macedonia, were screened for microbial colonies which form a clear zone of inhibition. The isolated bacterial strains were further screened for their antimicrobial activity against different bacteria and fungi by diffusion agar method. The isolates were later identified as Paenibacillus alvei and Bacillus subtilis by morphological studies and sequencing of the 16S rRNA bacterial gene. The maximum growth of P. alvei and B. subtilis for different cultivation media, pH, temperature, time of incubation and glucose concentration were determined. Maximum growth of P. alvei and B. subtilis was observed in MHB, at pH 6 after 24 hours of incubation at 30 °C for P. alvei, and at pH 7 after 48 hours at 40 °C for B. subtilis. In conclusion, the identified strains with antimicrobial activity in this study are a useful addition to the worldwide effort for new antibiotic discovery.

74-80

Authors: Zheleva, P., Vasileva, T., Bivolarski, V., Iliev, I.

A β-Galactosidase preparation from ten strains Lactobacillus plantarum was evaluated as a biocatalyst for the synthesis of oligosaccharides. Among them, the enzymes from L. plantarum S26 and L. plantarum S30 were selected for further studies. The correlation between organic acid production, α-galactosidase, β-galactosidase and lactate dehydrogenase activity and the initial concentration of lactose and lactulose was studied. It could be suggested that the studied β-galactosidase catalyzes the trans-glycosylation reaction at 20% lactose and 20% lactulose concentrations.

85-93

Authors: Trigueros, D. E. G., Kroumov, A. D.

The paper presents the modeling approach to aerobic biodegradation of 1,2-dichloroethane (1,2-DCE) by the microorganism Xanthobacter autotrophicus GJ10, and of trichlorethylene (TCE) by the microorganism Pseudomonas cepacia PR131 in a bioreactor with an ultrafiltration (UF) membrane unit. The aim of the study was to estimate the kinetics of the bioprocess and to perform a parameter identification procedure. The specific growth rate was assumed to be a function of 1,2-DCE and TCE and oxygen substrate concentrations. The parameter values were estimated based on experimental data of continuous and discontinuous systems published elsewhere. For this purpose, the Particle Swarm optimization algorithm, coded in Maple 15® software, was applied. Simulations with the developed kinetic model showed new highlights and an optimal trajectory that can help to increase organochlorine wastewater treatment efficiency.