Abstract:
Riboflavin, known as vitamin B2, is an essential part of the bacterial metabolism process. Also, it is a vitamin that vertebrates, including humans, cannot produce and obtain by themselves. Over the decades, there’s been several suggestions to increase riboflavin producing abilities of microorganisms. Bioelectrofermentation is a process which combines classical microbial fermentation with electrochemistry, by using electroactive microorganisms to transfer electrons either from or to an electrode. The main goal is to convert organic matter into more efficient biofuels or other high-value chemicals compared with microbial fermentation processes. The aim of the thesis research is to investigate the effect of electrochemical stimuli on the production of riboflavin by the Lactococcus lactis. In the research electroanalytical methods were used, such as cyclic voltammetry (CV), chronoamperometry (CA), and differential pulse voltammetry (DPV) to assess the electrochemical activity of L. lactis and its impact on the riboflavin yields. The 2-hydroxy-1,4-naphthoquinone (2-HNQ) redox mediator was employed in electrofermentation experiments to investigate its effect on bacterial activity. The objective of this investigation was to assess the potential of 2-HNQ to modulate the electrochemical behavior of bacteria during fermentation. The results of the electrochemical analysis using the 2-HNQ redox mediator at low concentrations of 12.5 and 25 μM at 0.4 V indicated that the electrical activity of L. lactis had no significant difference. Among the L. lactis B-RKM 0357, L. lactis B-RKM 0358, L. lactis B-RKM 0042 and L. lactis BRKM 0044 strains, L. lactis B-RKM 0357 showed the highest amount of riboflavin yields ((2.5 ± 0.004)*10-7 μg/CFU) after 24 h. incubation. Although, after electrofermentation, the amount of riboflavin arose for 12% ((2.8± 0.038)*10-7 μg/CFU). Additional investigation will be necessary to assess the impact of varying voltages and using diverse redox mediators.