Investigating lactic acid bacteria genus Lactococcus lactis properties: Antioxidant activity, antibiotic resistance, and antibacterial activity against multidrug-resistant bacteria Staphylococcus aureus.

Background: Lactic acid bacteria (LAB) are utilized as a starter culture in the manufacturing of fermented dairy items, as a preservative for various food products, and as a probiotic. In our country, some research has been carried out, even if LAB plays a principal role in food preservation and improves the texture and taste of fermented foods, that is why we tried to evaluate their probiotic effect. The objective of this research was to determine the antibacterial activity of Lactococcus lactis (L. lactis) against Staphylococcus aureus (S. aureus) ATCC 29213, investigate their antioxidant activity, and characterize their sensitivity against 18 antibiotics. Methods: A total of 23 LAB (L. lactis subsp. cremoris, L. lactis subsp. Lactis diacetylactis, L. lactis subsp. lactis) were isolated from cow's raw milk. The antibacterial activity was performed using two techniques, competition for nutrients and a technique utilizing components nature, using the disk diffusion method. The sensitivity of the studied LAB to different antibiotics was tested on Man rogosa sharp (MRS) agar using commercial antibiotic disks. All strains of LAB were examined for their antioxidant activity. The antioxidant activity of L. lactis was tested by 2,2-diphenyl-1 picrylhydrazyl (DPPH). Results: The results showed that the MRS medium was more adapted than Muller Hinton Agar (MHA) to investigate the antibacterial activity of L. lactis against S. aureus ATCC 29213. Also, L. lactis exhibited a notable degree of antibacterial activity against S. aureus ATCC 29213. L. Lactis subsp. Lactis displayed higher antibacterial activities, followed by L. lactis ssp. lactis biovar. diacetylactis, and lastly, L. lactis ssp. cremoris against S. aureus ATCC 29213. Lc 26 among all strains of L. lactis showed a high potential antibacterial activity reaching 40 ± 3 mm against S. aureus ATCC 29213. All strains of L. lactis showed a slightly moderate antioxidant activity (10.56 ± 1.28%-26.29 ± 0.05 %). The results of the antibiotic resistance test indicate that all strains of L. lactis were resistant to cefotaxime, sulfamethoxazole-trimethoprim, and streptomycin and were sensitive to Ampicillin, Amoxicillin, Penicillin G, Teicoplanin, Vancomycin, Gentamicin 500, Tetracycline, and Chloramphenicol. These test results indicate that this strain falls within the criteria of not posing any harmful effects on human health. The important antibacterial properties recorded for all L. Lactis strains were derived from the production of antibacterial active metabolites, such as protein, diacetyl, hydrogen peroxide, and lactic acid, together with the fight for nutrients. Conclusion: This study suggests that the strains of L. lactis could be added as an antibacterial agent against S. aureus ATCC 29213 and can provide an important nutritional property for their antioxidant potential.

Combined Effect of Protease, Hemicellulase and Pectinase on the Quality of Hemp Seed Oil (Cannabis sativa L.) Obtained by Aqueous Enzymatic Extraction as an Eco-friendly Method.

The objective of this research was to evaluate the efficiency of aqueous enzymatic extraction (AEE) to obtain oil from hemp seeds (Cannabis sativa L.) grown in northern Morocco. Optimisation of AEE extraction parameters, including pH, enzyme concentration (hemicellulase, protease and pectinase), temperature and incubation time, to maximize oil yield was achieved using response surface methodology with a central composite design. For comparison, the solvent extraction (Soxhlet) (SE) method was also used. Optimized hydrolysis conditions involved incubation for 4 hours at 60°C with a pH of 6.5, using a multi-enzyme preparation comprising protease, hemicellulase and pectinase at concentrations of 55, 202.5 and 234 U/mg, respectively. Referring to the conventional Soxhlet extraction (SE), Aqueous Enzymatic Extraction (AEE) achieved a 30.65% oil recovery rate under the optimized parameters mentioned above. The use of enzymes produced an oil that was more stable against oxidation than the solvent-extracted oil, with a peroxide value (PV) of 19.54 and 47.87 meq O 2 /kg, respectively. Furthermore, HPLC-DAD analysis of tocopherol content indicated a higher total tocopherol content (547.2 mg/kg) in Aqueous Enzymatic Extraction (AEE) compared to Soxhlet Extraction (SE) (513.51 mg/kg), with γ-tocopherol being the predominant form. No significant differences in fatty acid composition were observed between the two extraction methods with linoleic acid and alpha-linolenic acid being the predominant constituents.

Bioactive compounds from hemp (Cannabis sativa L.) seeds: optimization of phenolic antioxidant extraction using simplex lattice mixture design and HPLC-DAD/ESI-MS2 analysis.

The extraction of phenolic compounds from defatted hempseeds was optimized using a simplex lattice mixture design with three solvents (water, methanol, and acetone). The response variables were total phenolic content (TPC) and antioxidant activity evaluated by different spectrophotometric tests. The results showed that the binary acetone-water mixture in equal proportions is the optimal combination to achieve the maximum TPC (53.65 mg GAE per g extract) with higher antioxidant activities (265.53, 36.25, 119.03, 69.46, and 68.91 mg TE g-1 extract for the TAC, DPPH, ABTS, FRAP, and CUPRAC tests respectively). In addition, the phenolic profile analysis of defatted hemp seeds by HPLC-DAD/ESI-MS2 techniques showed the predominance of hydroxycinnamic acid amides and lignanamides. It allowed visualizing the effect of each solvent mixture on the relative extracted amount of each identified phenolic compound. This study suggests that N-trans-caffeoyltyramine, cannabisin A, and cannabisin B might contribute strongly to the potent antioxidant activity of hempseed extracts. Thus, it encourages the use of defatted hemp seeds as a source of antioxidants with added value for pharmaceutical and cosmetic applications.