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Background: Pyrazinamide (PZA) represents a milestone as a first-line antituberculosis drug due to its sterilizing activity against Mycobacterium tuberculosis. Materials & Methods: The protein changes induced by subinhibitory PZA exposure of M. tuberculosis in acidic pH were evaluated by a proteomic approach. Results: Among the 1059 M. tuberculosis proteins identified, the specific acidification in the culture medium induced the over-representation of MurF (Rv2157c), and its under-representation was induced by 12 h of PZA exposure. PanB (Rv2225) was over-represented at 24 h of PZA exposure. Conclusion: The authors highlight the over-representation of PanB in M. tuberculosis correlates of PZA action in acidic pH, reinforcing the role of the pantothenate pathway as a bacillus drug target to be explored.

Hibiscus calyx presents high content of bioactive compounds, such as anthocyanins and other phenolic compounds responsible for antioxidant activity. The present study investigated how the tea infusion temperature (hot and cold) can change the phytochemical profile, antimicrobial activity, and stability of hibiscus tea. The results indicated the same phytochemical profile for cold (infusion during 2 h/25 °C) and hot (7 min/75 °C) tea by using FTIR and UPLC-MS/MS analyses. Hibiscus tea, hot or cold, showed antimicrobial activity against strains of Salmonella Typhimurium, Pseudomonas aeruginosa, Escherichia coli and Staphylococcus, with minimum inhibitory concentration (MIC), obtaining values between 62.5 and 125.0 mg/ml. The hot infusion was more efficient for the bioactive compounds extraction, being 47% higher for total anthocyanins. After 48 h at 5 °C, the anthocyanin content had an average decrease of 30% (cold tea) and 48% (hot tea). Tea cream content increased to 15% (cold tea) and 37% (hot tea) after 72 h storage. Regarding the color, it was observed that after 48 h storage there was a clearing of the teas, and the L* coordinate increased from 21.03 to 24.93, and 20.72 to 24.90 for cold and hot tea, respectively. Our study indicates that hibiscus tea provides more antioxidants when prepared in the hot condition (7 min at 75 °C), and soon after cooled to 5 °C. Finally, it is recommended that hibiscus tea be consumed up to 24 h from preparation even when kept refrigerated.

Biofilms formed on food contact surfaces are a challenge for health authorities and industries due to health impact and economic losses caused by microbial contamination of foodstuffs. In this regard, studies about biofilm prevention, control, and disassembly employing antimicrobial photodynamic therapy (aPDT) have been done in the past few years. On this technique, the antimicrobial effect is attributed to reactive oxygen species (ROS) generated when light, oxygen, and a photoactivatable molecule—called photosensitizer (PS)—are combined. The mechanistic events found in aPDT, the main classes of PS, and light sources will be addressed in this chapter. It will highlight the recent researches employing aPDT for biofilm control in food science and technology field.

Rifampicin plays an important role during the treatment of tuberculosis, which makes it to be recommended throughout the regimen. The molecular target for rifampicin activity and resistance is the bacterial RNA polymerase coded by rpoB. However, it has been observed that Mycobacterium tuberculosis could use different metabolic pathways contributing to drug activity/resistance. In this sense, Proteomics analysis has been a key aspect towards the understanding of the dynamic genome expression triggered by drugs and other M. tuberculosis hostile stimuli. Herein, we aimed to report the changes in the M. tuberculosis protein profile triggered by rifampicin. The M. tuberculosis H37Rv strain was submitted to 12, 24 and 48 h of rifampicin challenge, at the minimal inhibitory concentration (0.03 μg mL−1), and proteins were extracted. The protein identification was carried out by liquid chromatography coupled to mass spectrometry (LC-MS). Four proteins, Ino1 (Rv0046c), FabD (Rv2243), EsxK (Rv1197) and PPE60 (Rv3478) were statistically underexpressed over 48 h of rifampicin exposure, indicating that in addition to the known activity of rifampin in transcriptional machinery in M. tuberculosis, processes related to disturbance in cell wall synthesis and lipid metabolism in the bacillus are also triggered by rifampicin contributing to bacillus death.