Antibacterial effect of crude water-soluble arrowroot (Puerariae radix) tea extracts on food-borne pathogens in liquid medium

Abstract

Aims:To evaluate the effect of crude water-soluble arrowroot tea extracts on microbial growth of food-borne pathogens in liquid medium and to confirm the damage to bacterial cells using Transmission Electronic Microscopy (TEM). Methods and Results: Inhibition of growth of Escherichia coli O157:H7, Salmonella enterica serovar Enteritidis, Listeria monocytogenes and Staphylococcus aureus was investigated using Brain Heart Infusion (BHI) broth containing 0 (control), 0AE63, 1AE25, 2AE5 and 5AE0% (w/v) arrowroot tea. Bacterial cell counts were performed on specific selective agar on days 0, 1, 3 and 5. BHI containing 5AE0% arrowroot tea extract showed a 6-7 log suppression of growth for all test strains on days 3 and 5, compared with the control. Even 0AE63% arrowroot tea effectively inhibited microbial growth of all test strains on day 5. TEM images of the samples treated with 5AE0% arrowroot tea revealed the rupture of cell walls and nonhomogeneous disposition of cytoplasmic materials within treated bacteria. Conclusions: Crude water-soluble arrowroot tea extract strongly inhibited microbial growth of all test pathogens in liquid medium. Significance and Impact of the Study: Water-soluble arrowroot tea extract has the potential to be used directly on foods or as a spray on the surfaces of food handling and processing facilities in order to prevent microbial growth of both Gram-negative and Gram-positive bacteria.

Antimicrobial efficacies of plant extracts and sodium nitrite against Clostridium botulinum

“…Such phenomenon further results in the reduction of pH and ATP concentration and ultimately leads to cell death. Kim and Fung (2004) similarly observed cracking on the bacterial cell wall after exposure to turmeric extract while Ultee and Kets (1999) also attributed cellular death to reduction of cellular ATP concentration after exposure of B. cereus to carvacrol.…”

Heat-sensitizing effects of plant extracts on Clostridium spp. spores

“…Ultee, Kets, and Smid (1999) reported that carvacrol, a naturally occurring compound in oregano and thyme extracts increases the permeability of the membrane of B. cereus cells that leads to dissipation of ionic gradient and eventually inactivates cells. Furthermore, cell membrane disruption and cytoplasm leakages were similarly reported to be the effects of extracts from other herbs and spices against various food borne pathogens (Kim & Fung, 2004;Oussalah, Caillet, & Lacroix, 2006). Addition of salt counteracted the effects of licorice extract, significantly reducing the total amount of inactivated spore population with increasing NaCl concentration.…”

Antimicrobial Activities of Leaf Extracts of Guava (Psidium guajavaL.) on Two Gram-Negative and Gram-Positive Bacteria

“…Several fruits and fruit extracts, as well as arrowroot tea extract [1] and caffeine [2], have been found to exhibit antimicrobial activity against E. coli O157:H7. This suggests that plants which manifest relatively high levels of antimicrobial action may be sources of compounds that can be used to inhibit the growth of foodborne pathogens.…”