Exploring the Antimicrobial and Hepatoprotective Effects of Kefir; A Probiotic Fermented Milk

El-Seedi H. The Many Faces of Kefir Fermented Dairy Products: Quality Characteristics, Flavour Chemistry, Nutritional Value, Health Benefits, and Safety

Kefir is a dairy product that can be prepared from different milk types, such as goat, buffalo, sheep, camel, or cow via microbial fermentation (inoculating milk with kefir grains). As such, kefir contains various bacteria and yeasts which influence its chemical and sensory characteristics. A mixture of two kinds of milk promotes kefir sensory and rheological properties aside from improving its nutritional value. Additives such as inulin can also enrich kefir's health qualities and organoleptic characters. Several metabolic products are generated during kefir production and account for its distinct flavour and aroma: Lactic acid, ethanol, carbon dioxide, and aroma compounds such as acetoin and acetaldehyde. During the storage process, microbiological, physicochemical, and sensory characteristics of kefir can further undergo changes, some of which improve its shelf life. Kefir exhibits many health benefits owing to its antimicrobial, anticancer, gastrointestinal tract effects, gut microbiota modulation and anti-diabetic effects. The current review presents the state of the art relating to the role of probiotics, prebiotics, additives, and different manufacturing practices in the context of kefir's physicochemical, sensory, and chemical properties. A review of kefir's many nutritional and health benefits, underlying chemistry and limitations for usage is presented.

Characterization of natural bioactive compounds produced by isolated bacteria from compost of aromatic plants

AIMS

This study aimed to highlight the importance of compost from aromatic plants as a stunning source for several bio active compounds generated from their inhabited thermophilic bacteria. Some of the isolated compounds could have a potential role in the treatment of microbial infections.

METHODS AND RESULTS

A total of forty different thermophilic bacteria were isolated from compost samples during their thermophilic stage. These isolates were tested for their antimicrobial capabilities against different Gram-positive and -negative bacteria using agar diffusion and double layer agar methods. The potential isolates were further identified based on morphological, biochemical and 16S rRNA gene sequencing methods. They were subjected to submerged state fermentation and the total crude metabolites were recovered using ethyl acetate (EtOAc) extraction. All bioactive metabolites were identified using liquid chromatography coupled with high-resolution mass spectrometry (LC-HRMS). It was observed that 2 out of 40 isolates were remarkably active against Gram-positive bacteria. These isolates were genetically identified as Bacillus species and their different active metabolites were characterized in the EtOAc extracts using LC-HRMS.

CONCLUSION

Liquid chromatography coupled with high-resolution mass spectrometry analysis of EtOAc extracts revealed the presence of active metabolites that are responsible for antimicrobial activities.

SIGNIFICANCE AND IMPACT OF THE STUDY

To the best of our knowledge, this is the first time to identify bioactive antimicrobial metabolites from retrieved compost micro-organisms in Egypt. So, compost could be a beneficial area for research as a reliable and continuous natural source for different uncountable communities of bacteria.