Study on Antibacterial Effect of Aloe Extract I: Materials and Methods

Study on Antibacterial Effect of Aloe Extract I: Materials and Methods

Wang Jinxu, Wang Xin, Ye Jingbo, Zhu Yiping, Guan Zhanwen, He Yanming (National Biology Experimental Teaching Center, Zhongshan College of Life Sciences, Guangzhou 510275, Guangdong)

Abstract:

[Objective] The research aimed to provide theoretical basis for the development and utilization of aloe in food industry.

[Method] With sodium benzoate as the control, using the filter paper method, the resistance and thermal stability of the extracts from the root, middle and tip of Aloe vera leaves were studied.

[Result] Different parts of aloe extract showed certain antibacterial effects on Staphylococcus aureus, Escherichia coli and Aspergillus niger, comparable to sodium benzoate, but the antibacterial effect on Saccharomyces cerevisiae was not very obvious. For various strains, the antibacterial effect of aloe extract had good thermal stability, and it still retained good antibacterial ability even after heat treatment.

[Ability] Aloe extract had a strong antibacterial effect on a variety of bacteria and molds, but had no inhibitory effect on Saccharomyces cerevisiae.

Main article:

Aloe, lily family aloe is a perennial evergreen succulent herb, native to Africa, widely distributed in tropical and subtropical regions. Aloe has many functions such as medical treatment, beauty treatment, health care, edible, ornamental and so on. Studies have shown that aloe has antibacterial and bactericidal effects, and anthraquinones are the main antibacterial substances in aloe. Aloe juice was extracted from the root, middle and tip of Aloe vera, and sodium benzoate (PH = 3 and PH = 6) was used as the control to study the antibacterial effect and thermal stability of aloe extract, which provided the basis for the development and utilization of aloe in the food industry.

1. Materials and Methods

1.1 materials: Aloe vera was used in the United States: Staphylococcus aureus, Escherichia coli, Aspergillus niger and Saccharomyces cerevisiae were used. The culture medium includes beef extract peptone medium (bacterial medium), LB medium (yeast medium) and potato medium (mold medium). All of them are provided by Microbiology Laboratory of School of Life Sciences, Sun Yat-sen University.

1.2 method:

1.2.1 Preparation of raw aloe juice. After washing fresh American aloe vera, it is disinfected with 0.11 KMhO4 and then rinsed with flowing water. The root, middle and tip of the leaf are taken respectively, the light green original method is squeezed out with a fruit and vegetable juicer, and filtered with 4 layers of gauze.

1.2.2 Preparation of bacterial suspension. The above four kinds of bacteria to be tested (Staphylococcus aureus, Escherichia coli, Aspergillus niger, Saccharomyces cerevisiae) were activated with a suitable slant, and a bacterial solution of 106-107cfu/ml was prepared with sterile saline.

1.2.3 Preparation of aloe extract instead of water culture medium. The aloe original method is diluted 10 times to prepare the aloe solution, and the solution is used instead of distilled water to prepare the medium for standby.

1.2.4 Determination of antibacterial effect by filter paper method. Take sterilized filter paper pieces with a diameter of 7mm and soak them in aloe juice for 24 hours. Take 0.5ml of each bacterial suspension to be tested and the corresponding solid medium to make a bacterial-containing plate. Use sterile tweezers to take filter paper pieces containing aloe and stick them on the bacterial-containing plate. Paste 3 pieces on each dish and repeat 3 times for each bacterial. The results were observed after the bacteria were cultured at (37±1)0C for 18-24h, and the fungi were cultured at 280C for 48h. Sodium benzoate (pH = 3 and pH = 6) was additionally used as a control. The size of the bacteriostatic zone of the filter paper was measured and the bacteriostatic effect was compared.

1.2.5 Aloe juice resistance assay. In a variety of aloe extract instead of water in the culture medium were inoculated with a variety of bacteria to be tested, with the corresponding culture medium prepared with distilled water inoculation as a control. Appropriate temperature culture, observe the growth.

(Study on the antibacterial effect of aloe extract to be continued)