Arils from six pomegranate (Punica granatum L.) varieties grown in the Mediterranean region of Turkey were tested for their antimicrobial properties by the agar diffusion and minimum inhibitory concentration (MIC) methods against seven bacteria: (Bacillus megaterium DSM 32, Pseudomonas aeruginosa DSM 9027, Staphylococcus aureus Cowan 1, Corynebacterium xerosis UC 9165, Escherichia coli DM, Enterococcus faecalis A10, Micrococcus luteus LA 2971), and three fungi (Kluvyeromyces marxianus A230, Rhodotorula rubra MC12, Candida albicans ATCC 1023). It has been observed that the pomegranate aril extracts had antimicrobial effect on all microorganisms, giving inhibition zones ranging in size from 13 to 26 mm. The MIC values for active pomegranate extracts ranged between 30 and >90 µg/mL. The results obtained appeared to confirm the antimicrobial potential of the Punica granatum varieties.

Essential oils from Ocimum basilicum L. and Coriandrum sativum L. varieties originating from Turkey were investigated for their antimicrobial properties. The antimicrobial effects of the oil varieties were evaluated by the disc diffusion and minimum inhibitory concentration (MIC) methods against eight bacteria and three fungi. The compositions of the essential oils were analyzed and identified by GC and GC-MS. O. basilicum, C. sativum var. macrocarpum and var. microcarpum oils revealed the presence of linalool (54.4%), eugenol (9.6%), methyl eugenol (7.6%); linalool (78.8%), γ-terpinene (6.0%), nerol acetate (3.5%); and linalool (90.6%), and nerol acetate (3.3%) as the major components, respectively. The oils exhibited antibacterial activity ranging from 1.25 to 10 µL disc-1 against the test organisms with inhibition zones of 9.5-39.0 mm and minimal inhibitory concentrations values in the range 0.5-≥1µL/L. Linalool, eugenol, and methyl eugenol at 1.25 µL disc-1 had antimicrobial effects on all microorganisms, giving inhibition zones ranging from 7 to 19 mm.

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Metabolic engineering in Lactic acid bacteria (LAB) has focused on changing of pyruvate metabolism to increase production of desired flavor compounds. A constructed mutant strain should contain no foreign DNA and antibiotic resistance genes. Therefore, food grade lactate dehydrogenase (ldh d ) and diacetyl reductase (dar d ) mutant strains were created using two plasmid system in this study. Metabolic end products (pyruvate, lactate, formate and acetoin) of these strains in glucose medium and in cheese were determined using HPLC. Created mutant and wild type strains were used as a starter culture in cheese. Compared to the wild type strain, different levels of metabolites were observed in cheese during three weeks of ripening. The ldh d strains produced less lactate but high acetoin as a result of gene deletion. Deletion of dar gene decreased the production of acetoin. The dar deficient strains have low diacetyl reductase activity and are able to reduce significant amounts of acetoin but not terminate it completely. Genetic modification made the shift from homolactic to mixed acid fermentation, but the desired compound production hardly improved. The basis of these results and techniques are promising for the further studies.

Exopolysaccharides are high molecular weight polymers of repeated sugar units with diverse chemical structure and unique properties and produced by microorganisms. Lactic acid bacteria are important exopolysaccharide producers. Lactic acid bacteria derived exopolysaccharides, one of the postbiotics, are known to have technological properties such as stabilizing, thickening, emulsifing and also biological activities. Lactic acid bacteria can synthesis exopolysaccharides with large structural variability and this diversity brings these polymers to possess several bioactivities. Bioactivities such as immunomodulatory, antiinflammatory, antitumor and antimutagenicity, antioxidant, antibacterial and antiviral, cholesterol-lowering, antihypertensive activity and gastro-protective activity bring these biopolymers commercial value in the global market and potential to be used in biomedical and pharmaceutical applications. Therefore, to evaluate the availability of these natural exopolysaccharides for new applications extensive understanding of the structure-function relationships will be required. In this review, it is presented a comprehensive overview for the most recent reports on the health benefits of postbiotic lactic acid bacterial exopolysaccharides.