Antibacterial activity of ethanol extracts of fifteen Bulgarian plants

A. Solak, S. Dyankova

Institute of Cryobiology and Food Technologies, 53 Cherni Vrah Str., 1407 Sofia, Bulgaria

(Manuscript received 1 September 2018; accepted for publication 16 January 2019)

Abstract. Analyses were performed of the antimicrobial activity of 15 herbs and spices (lemongrass, sour cherry, horseradish, ginger, St. John’s wort, common centaury, fig, clove, rose geranium, dill, rosemary, oregano, savory, smoketree and wild thyme) widely spread and used in Bulgaria and of some combinations thereof by the agar disk diffusion method. Total phenol content was the highest in the smoketree extract (43.80±1.50 GAE/ml), followed by rosemary (27.80±1.20 GAE/ml), clove (25.17±0.26 GAE/ml), wild thyme (24.83±1.20 GAE/ml), and oregano (23.50±2.00 GAE/ml) extracts. It was established that ethanol extracts of many tested plants showed inhibitory action against S. aureus and E. coli. The most potent effect was observed with extracts of St. John’s wort, smoketree and clove. With combination of plant extracts, very good results were demonstrated in mixtures of St. John’s wort with wild thyme, with savory and with clove. The said extracts may be used as active constituents in biopolymer matrices for development of functional antimicrobial films needed for food and pharmaceutical industries.

Antimicrobial activity of Lactobacillus acidophilus against pathogenic and food spoilage microorganisms: A review

T. Dinev1*, G. Beev1, S. Denev1, D. Dermendzhieva2, M. Tzanova1, E. Valkova1

1Department of Biochemistry, Microbiology and Physics, Faculty of Agriculture, Trakia University, 6000 Stara Zagora, Bulgaria 2Department of Applied Ecology and Animal Hygiene, Faculty of Agriculture, Trakia University, 6000 Stara Zagora, Bulgaria

(Manuscript received 23 November 2016; accepted for publication 17 February 2017)

Abstract. The purpose of this review is to summarize the information regarding the antimicrobial activity of Lactobacillus acidophilus, an important species of lactic acid bacteria. Lactic acid bacteria are constituents of many beneficent for the consumer’s health food products. They are considered potentially promising in the strategy to combat infections and prevent the growth of spoilage microorganisms, and also have antimutagenic, anticarcinogenic, hypolipidemic and hypocholesterolemic properties, improve the lactose metabolism, stimulate the immune system, etc. In the resent years Lactobacillus acidophilus is considered the main probiotic species in the intestinal tract of healthy humans and is widely used in functional dairy foods. It produces a variety of metabolic productswithantimicrobialproperties,includingorganicacidsandbacteriocins,suchaslactacinsBandF,acidophilin,acidocin,acidophilucin, acidophilicin, which are active against many pathogenic and spoilage microorganisms – Escherichia coli (including Escherichi coli 0157:H7), Staphylococcus aureus, Pseudomonas aeruginosa, Listeria monocytogenes, Vibrio parahaemolyticus, Vibrio cholerae, Helicobacter pylori, Klebsiella, Salmonella, Shigella, Bacillus, Clostridium, Mucor, Aspergillus, Fusarium, Trichoderma and Candida spp., etc. Because of the above mentioned reasons Lactobacillus acidophilus could be used as an alternative therapeutic agent against infections caused by susceptible microorganisms. On the other hand Lactobacillus acidophilus based antimicrobial products (mainly bacteriocins and pure cultures) could also be applied to food products to prevent the growth of spoilage microorganisms and food-borne pathogens. To better understand the mode of action and the spectrum of antifungal activity more clinical and laboratory studies of different Lactobacillus acidophilus strains are required.