Biomedical Engineering Reference
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biological control of animal pathogens. Toxicological tests performed by team from Institute
of Experimental Veterinary Reseach have shown that the selected strain is not toxigenic and
not pathogenic and hence it may be used in microbiological industry. It was demonstrated by
wells technique that strain
B. subtilis
B-454 D did not affect growth of species-constituents of
normal gut microbiota in young cattle -
Lactobacillus gasseri, Lactobacillus acidophilus,
as
evidenced by lack of growth inhibition zone in studied cultures.
Evaluating adhesive properties of
B. subtilis
B 454 D it was found that adhesion index of
the selected strain was less than 1, indicating its inability to colonize mucous membrane of
gastrointestinal tract and supporting its affiliation to exogenous transitory (auto-eliminating)
microflora.
Investigations into impact of metabolites generated by selected bacterial strain on
immune system of lab test animals provided results confirming activation of immune humoral
factors. It was detected that in 5 days after per oral administration the levels of lysozyme and
interferon in blood serum raised by 20-40%.
Table1. Antimicrobial activity spectrum of strain B. subtilis B-454 D
Test culture
B. subtilis
B-454 D
wells technique
I
replica method
II
Escherichia coli
018 21.5±0.5 95.1
Escherichia coli
099 23.5±0.4 93.5
Proteus vulgaris
25.0±0.6 83.0
Salmonella holeraesuis
20.0±0.5 74.0
Klebsiella pneumoniae
21.5±0.2 71.0
Pasteurella multocida
22.0±0.6 85.0
Staphylococcus sp
. 30.5±0.3 98.3
Staphylococcus aureus
6538-p 28.5±0.4 95.5
Streptococcus sp.
31.5±0.6 92.5
Note - antagonistic activity was assessed: I - via diameter of growth inhibition zone in test cultures,
mm; II - as size ration of experimental and control colonies of test cultures, %.
It was shown that optimal conditions for growth and synthesis of antimicrobial
metabolites by
B. subtilis
B-454 D in lab fermenter were reached at pH 7.0, temperature 30
ºC. aeration rate 1 l/l·min and agitation rate 200 rpm on modified Meynell medium with
molasses as a carbon source [9].
The obtained findings were used for running pilot plant technology of manufacturing new
probiotic product for prevention and treatment of enteritis and respiratory diseases of farm
stock at facilities of Biotechnological Center, Institute of Microbiology, National Academy of
Sciences, Belarus.
Optimization of technological parameters achieved during scale-up of
B. subtilis
B-454 D
fermentation process in pilot-plant bioreactors corroborated several correlations revealed in
the course of bacterial growth in 10 l laboratory fermenters ANCUM 2M.
It was found that low rate of air supply 0,8 l/l medium·min negatively affected growth
characteristics and antagonistic activity of strain-producer. Rise in aeration intensity to 1 and
1.5l/l·min resulted in more complete consumption of nutrient substrate and, as a consequence,
increased number of cells and spores in cultural medium. This is accompanied by maximal
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