Breastfeeding offers a multitude of health benefits to babies including strong immunity, cold and flu resistance, and lower risks of diabetes, asthma, dental problems and obesity later in life, to name a few.
The nutritional components of human breast milk are a balanced amount of carbohydrates, fats and proteins as well as vitamins, minerals, enzymes, hormones and other amazing bioactive molecules.
But, did you know that breast milk contains an array of healthy bacteria? This community is known as breast milk microbiome. This special microbiome supports the developing infant gut providing a diverse array of bacteria which also play an important role in regulating the immune system.
In order to identify bacteria in breast milk, bacterial extraction methods must yield genuine results. It has been found that different research groups use different methods that produce differing results. Douglas and colleagues have addressed this issue in a recent Nature paper (link below). This study was the first to assess the impact of DNA extraction methodologies on the characterisation of human breast milk microbiota.
To identify milk bacteria, firstly they must be destroyed, releasing their genomic DNA. The method of destruction could be mechanical or chemical, ranging in methodology from agitating the sample with tiny beads (bead-beating), to using phenol-chloroform-based methods. Different methodologies result in the distortion of actual types of bacteria in the profile and the number of bacteria in the sample.
Then once the milk bugs have been extracted, the favored method for their characterization is 16S rRNA gene sequencing. The bacterial 16S rRNA gene is evolutionary stable, making it a perfect gene to target for consistent results. This is the method we use to identify bacteria extracted from your stool sample! This method also calculates the relative amount of bacteria in the sample, called the relative abundance.
Douglas and co-workers used ‘mock’ breast milk which contained a defined amount of a number of bacterial species. This enabled the researchers to compare their results with the actual bacterial profile of their mock sample and identify the methods that gave the most accurate results. This allows the researchers to analyze real breast milk with confidence. They found that identification of Bifidobacterium, Staphylococcus, Enterococcus, Lactobacillus and Escherichia-Shigella did not differ significantly between any of the kits. Whereas Streptococcus was significantly underrepresented when the milk bacteria were extracted using a kit called a QIAamp DNA Mini Kit.
By carrying out methodology research it confirms the potential for reported bacterial constituents of breast milk to be artefacts. Although this cutting edge technology unlocks the ability to identify key bacteria in biological human samples, it is critical the correct methods and reagents are used to provide authentic results.
If you are interested you can read the article published in Nature January 2020 here …