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Zuzana Hladíková, Jana Smetanková, Gabriel Greif and Mária Greifová

Antimicrobial activity of selected lactic acid cocci and production of organic acids

Antimicrobial activity and production of organic acids by selected lactic acid bacteria were monitored in this study. The largest antimicrobial activity against indicator microorganisms showed Pediococcus sp. G5, whereas Streptococcus thermophilus had no inhibitory effect. The inhibitory effect of Pediococcus sp. G5 was strongest against Bacillus subtilis (17.78 %). Lactococci inhibited the growth of Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus (% of inhibition ≤ 5.25). The growth of Asperglillus flavus, Penicillium funiculosum and Rhizopus oryzae was not inhibited by all of tested cocci. Cocci produced varying quantities of organic acids (lactic acid, acetic acid, succinic acid, etc.). Lactic acid was in large amounts and phenyllactic acid was produced only by Pediococcus sp. G5 (49.65 mg/L).

Open access

Jana Smetanková, Zuzana Hladíková, František Valach, Michaela Zimanová, Zlatica Kohajdová, Gabriel Greif and Mária Greifová

Abstract

Three wild strains of Lactobacillus plantarum were investigated for their growth and ability to produce lactic acid, acetic acid and ethanol under aerobic and anaerobic conditions. They were tested at three different temperatures (30 °C, 37 °C and 45 °C). The growth of lactobacilli was studied by measuring optical density (OD) at λ = 600 nm and pH value at the following times. With increasing temperature difference of cell yield was observed. The final cell yield under aerobic conditions was higher. Organic acids and ethanol were analysed using an HPLC RID method. Formation of lactic acid (as the major metabolite) was the slowest during cultivation at 30 °C, but the final amount of lactic acid showed the highest values. Concentrations of metabolites produced by lactobacilli after 48th hours of cultivation were: 9.18-11.48 g.dm-3 (lactic acid), 0.84-1.65 g.dm-3 (acetic acid) and 2.51-4.03 g.dm-3 (ethanol). No significant differences (p = 0.05) were found in production of lactic acid and ethanol by different bacterial strains under aerobic and anaerobic conditions. Statistically significant differences (p = 0.05) were observed in production of acetic acid by 2L2 under aerobic and anaerobic conditions and for production of ethanol under anaerobic conditions by strains 1L5 and 2L2.