The methylated soybean protein and methylated chickpea protein (MSP and MCP) with isoelectric points around pI 8 were prepared by esterifying 83 % of their free carboxyl groups and tested for their interactions with Listeria monocytogenes and Salmonella Enteritidis. The two substances exhibited a concentration-dependent inhibitory action against the two studied bacteria with a minimum inhibitory concentration of about 100 μg/mL. The IC50 % of the two proteins against L. monocytogenes (17 μg/mL) was comparable to penicillin but comparatively much lower (15 μg/mL) than that of penicillin (85 μg/mL) against S. Enteritidis. The two proteins could inhibit the growth of L. monocytogenes and S. Enteritidis by about 97 and 91 %, respectively, after 6-12 h of incubation at 37 °C. The constituting subunits of MSP (methylated 11S and methylated 7S) were both responsible for its antimicrobial action. Transmission electron microscopy of the protein-treated bacteria showed various signs of cellular deformation. The cationic proteins can electrostatically and hydrophobically interact with cell wall and cell membrane, producing large pores, pore channels and cell wall and cell membrane disintegration, engendering higher cell permeability leading finally to cell emptiness, lysis and death.

Supplementation of raw milk with 0.5% methylated soybean protein (MSP) or methylated chickpea protein (MCP) delayed its spoilage at room temperature (25C) and extended its technological validity up to 12 h instead of 6 h in case of the control. Titratable acidity and pH reached respective levels of 0.22 and 6.30 in raw milk provided with 0.5% esterified legume protein after 12 h of storage at room temperature against 0.49 and 4.64 in case of control. MSP (0.5%) delayed casein degradation to the 24th hour instead of 12 h in case of control and extended milk stability to heat and ethanol to 12 h instead of 6 h in case of control. Total mesophilic bacteria, Pseudomonas spp. and Enterobacteriaceae counts, in MSP‐ and MCP‐supplemented raw milk were lower by about 1.9–2.0 log as compared with control after 12 h of storage at room temperature. Practical Applications Extending the technological milk validity from 6 to 12 h will help avoid big losses of raw milk and enhance its chances to be incorporated into many dairy products while avoiding hygienic, chemical and technological deterioration.

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The biologically active compounds isolated from plants are known to be efficient as antibacterial and antioxidants. The antioxidant and antibacterial activities of total phenols and flavonoids drived from the petroleum ether, ethyl acetate and ethanol extracts of Opuntia ficus-indica seeds and peels were performed using DPPH and modified Kirby-Bauer disc diffusion technique against gram-positive bacteria (Bacillus subtilis) and gram-negative bacteria (Serratia marcescens), respectively. In the present study, it is demonstrated that, both alcohol and ethyl acetate extracts show the best antioxidant and antibacterial activities than the petroleum ether extracts. This is consistent with the results of the chemical analyses of both extracts.

Natural substances of botanical origin have been important in African traditional medical practice. They have been used for various illnesses such as infections. Infectious diseases caused by pathogenic bacteria affect many communities and the treatment was made difficult partly because of antibiotic resistant strains. Phytochemicals isolated from medicinal plants are known to be effective in treating bacterial infections. The antibacterial activities of the ethanol and water leaf extracts of Codiaeum variegatum were tested. Antibacterial effects of crude extracts were performed using modified Kirby-Bauer disc diffusion technique to determine the zone of inhibition. The extracts were tested for the antibacterial activities against Gram-positive bacteria (Bacillus subtilis) and Gramnegative bacteria (Serratia marcescens). The results demonstrated that both of ethanol and water leaf crude extracts of Codiaeum variegatum have shown strong zone of inhibition against Serratia marcescens (20 mm) and Bacillus subtilis (12 mm) compared to control. This medicinal plant could be developed into affordable and safe standardized herbal products and may serve as a source of new molecules for broad-spectrum antimicrobial agents.