RESUMEN
Growth of members of most of the studied genera of gram-positive (Dietzia, Kocuria, and Rhodo- coccus) and gram-negative bacteria (Pseudomonas and Chromobacterium) in biofilms exhibited higher resistance to an translation inhibitor, azithromycin compared to the growth of planktonic cultures of the same strains. Low concentrations of azithromycin were found to stimulate biofilm formation by the studied saprotrophic strains. The rate of synthesis of the polysaccharide matrix component exceeded the rate of cell growth, indicating implementation of the biofilm phenotype under these conditions. It was found that an alkylhydroxybenzene (AHB) compound 4-hexylresorcinol was capable of almost uniform suppression of growth of both planktonic cultures and biofilms of the saprotrophic strains under study. In some cases, combined action ofazithromycin and AHB resulted in an additive inhibitory effect and prevented the stimulation of biofilm growth by subinhibitory azithromycin concentrations. Thus, AHB may be considered a promising antibiofilm agent.
Asunto(s)
Actinomycetales/efectos de los fármacos , Azitromicina/farmacología , Biopelículas/efectos de los fármacos , Hexilresorcinol/farmacología , Micrococcaceae/efectos de los fármacos , Rhodococcus equi/efectos de los fármacos , Actinomycetales/fisiología , Antibacterianos/farmacología , Azitromicina/antagonistas & inhibidores , Biopelículas/crecimiento & desarrollo , Chromobacterium/efectos de los fármacos , Chromobacterium/fisiología , Combinación de Medicamentos , Micrococcaceae/fisiología , Plancton/efectos de los fármacos , Plancton/crecimiento & desarrollo , Polisacáridos Bacterianos/agonistas , Polisacáridos Bacterianos/antagonistas & inhibidores , Polisacáridos Bacterianos/biosíntesis , Pseudomonas/efectos de los fármacos , Pseudomonas/fisiología , Rhodococcus equi/fisiologíaRESUMEN
BACKGROUND: A lot of interesting research has been undertaken to enhance the yield of exopolysaccharides (EPS) produced by lactic acid bacteria (LAB). The objective of this study was to determine the influence of casein hydrolysates (CH) with molecular weight less than 3 kDa on cell viability, EPS synthesis and the enzyme activity involved in EPS synthesis during the co-culturing of Streptococcus thermophilus and Lactobacillus delbrueckii ssp. bulgaricus in MRS broth for 72 h at 37 ± 0.1 °C. RESULTS: The highest EPS yield (150.1 mg L⻹) was obtained on CH prepared with papain (CHP) at 48 h. At 24 h, EPS were composed of galactose, glucose and rhamnose in a molar ratio of 1.0:2.4:1.5. The monosaccharide composition changed with extension of the fermentation time. The activities of α-phosphoglucomutase, uridine 5'-diphosphate (UDP)-glucose pyrophosphorylase and UDP-galactose 4-epimerase were associated with EPS synthesis. Moreover, the activities of ß-phosphoglucomutase and deoxythymadine 5'-diphosphate (dTDP)-glucose pyrophosphorylase involved in rhamnose synthesis were very low at the exponential growth phase and could not be detected during other given periods. CONCLUSION: The influence of different CH (<3 kDa) on LAB viability, EPS production, EPS monomeric composition and activity levels of key metabolic enzymes was distinct. Besides, their influence was related to the distribution of amino acids.