Domenico Carminati

Characterization of fructophilic lactic microbiota of Apis mellifera from the Caucasus Mountains

Microbial symbionts of honeybee colony are considered as promising tools to support the honeybee population welfare. The majority of existing honeybee microbiota studies is focused on genetic description of the honeybee-associated microbiome fingerprints. The lack of a deeper knowledge on the bacterial community colonizing the honeybee niche, which may be helpful in encouraging industrial applications of this microbiota, led us to undertake this study. The biodiversity of the cultivable fructophilic lactic acid bacteria (FLAB) isolated from adult honeybee intestine and beebread samples was studied. Phenotypic properties of probiotic interest, such as the adhesive potential using in vitro models and adhesion determinants, were also investigated. Antibiotic resistance profiles as reliable markers to evaluate the impact of long-term and current exposure of honeybees to antibiotics were phenotypically determined on the isolated lactic acid bacteria (LAB). The mannose-specific adhesion and high cell surface hydrophobicity found in the studied FLAB isolates sheds light on the effective adaptation of microbiota to specific ecologic niche. It is the first report of phenotypically detected antibiotic resistance profiles of honeybee endogenous bacteria and the first account of minimum inhibitory concentration (MIC) values for four antibiotics used in beekeeping practice.

Applicability of Lactococcus hircilactis and Lactococcus laudensis as dairy cultures

The aim of this study was to evaluate whether Lactococcus hircilactis and Lactococcus laudensis can be used as starter cultures. To this end, the two lactococci were characterized for traits of technological and functional interest. Tests in milk included growth at 20, 25, 30, and 37 °C, flavor production, antioxidant (AO) activity, folate and exopolysaccharide (EPS) production. At 30 °C, which resulted the best growth temperature for both strains, Lc. hircilactis and Lc. laudensis lowered the pH of the milk to 4.8 and 5.5, respectively, after 24 h of incubation. Sugar and organic acid composition indicated a higher lactose utilization, coupled with a higher lactate accumulation, by Lc. hircilactis, while galactose was completely consumed by both species. Both strains showed a Cit- phenotype after growth in a selective medium containing citrate as the sole carbon source. Nevertheless, a small amount of citrate was used by both lactococci when grown in milk. The two strains were characterized by a different flavor production, showed high AO activity, and produced small amounts of EPS (~30 mg/L). Lactococcus laudensis showed a weak proteolytic activity while Lc. hircilactis was able to accumulate folate at levels four times higher than uninoculated milk. When the two lactococci were tested as starter cultures in small-scale cheesemaking trials, cheeses resulted of satisfying quality and contained amounts of ethanol, acetic acid, diacetyl and acetoin higher than controls, obtained using a commercial culture. The application of Lc. hircilactis and Lc. laudensis as aromatic cultures in cheesemaking is proposed.

Nutritional Value and Potential Health Benefits of Donkey Milk

Abstract Donkey milk has a growing interest due to its composition similar to human milk, with good tolerability and palatability. Many pediatricians suggested donkey milk in the infant’s diet as a valid alternative in terms of nutritional adequacy for subjects affected by allergy to cow milk proteins. It is rich in lactose and whey proteins, contributing to the intestinal absorption of calcium, essential for bone mineralization. Additionally, due to the low fat content and favorable lipid composition, donkey milk and derived products are also valuable foods for elderly consumers. The presence of endogenous bioactive compounds increases some other alleged health benefits, as the antibacterial activity, the stimulation of immune system, the prevention of inflammatory diseases, and antiaging properties. The attractive characteristics of donkey milk, also defined as a nutraceutical product, seems to meet the growing consumer’s demand for natural and health-promoting foods.

Genomic diversity and immunomodulatory activity of Lactobacillus plantarum isolated from dairy products

In this study, we aimed to investigate some functional characteristics and the immunomodulatory properties of three strains of Lactobacillus plantarum of dairy origin which, in a previous screening, showed to be candidate probiotics. Genome sequencing and comparative genomics, which confirmed the presence of genes involved in folate and riboflavin production and in the immune response of dendritic cells (DCs), prompted us to investigate the ability of the three strains to accumulate the two vitamins and their immunomodulation properties. The ability of the three strains to release antioxidant components in milk was also investigated. Small amounts of folate and riboflavin were produced by the three strains, while they showed a good antioxidant capacity in milk with FRAP method. The immune response experiments well correlated with the presence of candidate genes influencing in DCs cytokine response to L. plantarum. Specifically, the amounts of secreted cytokins by DCs after stimulation with cells of Lp790, Lp813 and Lp998 resulted pro-inflammatory whereas stimulation with culture supernatants (postbiotics) inhibited the release of interleukin (IL)-12p70 and increased the release of the anti-inflammatory IL-10 cytokine. This study adds further evidence on the importance of L. plantarum in human health. Understanding how probiotics (or postbiotics) work in preclinical models can allow a rational choice of the different strains for clinical and/or commercial use.