# An Insight into Probiotics Bio-Route: Translocation from the Mother's Gut to the Mammary Gland
## 3 Microbial Partners of Human Milk 'Factory'
### Human Milk Is a Probiotic Consortium  
[PERSON] and colleagues [37] performed one of the earliest isolations on probiotics from HBM. The study successfully described 78 rod-shaped lactic acid bacterial isolates that grew on MRS medium [37]. The presence of _Lactobacillus_ and _Bifidobacterium_ strains in the human milk has also been confirmed by other studies [38; 39; 40]. [PERSON] and [PERSON] [38] described the occurrence of _Lactobacillus reuteri_ strains in 220 breast milk samples by the culture-dependent method. [PERSON] and [PERSON] [41] characterized 100 presumptive _Lactobacillus_ isolates from colostrum samples by using the API 50 CHL system from BioMerieux. This study identified several _Lactobacillus_ strains of _Lactobacillus brevis_, _Lactobacillus plantarum_, _Lactobacillus fermentutum_, _Lactobacillus rhamnosus_, and _L. reuteri_. However, certain lactic acid bacterial isolates share common phenotypes [41]. [PERSON] et al. [42] utilized qualitative PCR analysis, which revealed the presence of _Lactobacillus_ and Bifidobacterial DNA in 160 samples. The most frequently detected _Lactobacillus_ species were _L. salivarius_, _L. fermentutum_, and _L. gasseri_. The study also reported the presence of _Bifidobacterium breve_ as the most common Bifidobacterial species [42]. In addition, [PERSON] et al. [43] also found that the majority of probiotic bacterial OTUs, especially assigned to the Bifidobacterialgroup, were shared between breast milk and stool samples of the same mother-infant pairs. This gives credence to the idea that the mother's milk acts as a source of pioneer probiotic bacteria for the infant's gut microbiota [33; 43].  
Currently, more _Lactobacillus_ and _Bifidobacterium_ strains have been isolated from human milk to be utilized as potential probiotics [44; 45]. [PERSON] et al. [46] identified three _Lactobacillus_ strains recently isolated from human milk that exhibited probiotic properties. The study also reported anti-cancer properties in their cell-free culture supernatants. [PERSON] et al. [5] characterized three probiotic potential strains, namely _L. gasseri_; _B. breve_, and _L. salivarius_ from healthy human milk. These strains agglutinated with different pathogens instead of producing bactracin. Besides, _L. fermentum_ originating from human milk has been exploited extensively to treat mastitis problems [47]. Several orally administrated probiotic bacteria were also previously isolated from human milk samples [48; 49].  
Compared to many bacterial groups in mothers' milk, the presence of _Lactobacillus_ and _Bifidobacterium_ spp. has much more beneficial impact on the neonatal immune system [50; 51]. In addition, the presence of probiotic strains including _Lactobacillus_ and _Bifidobacteria_ has a protective role where these bacterial strains suppress respiratory and diarrheal infections at the initial infantile age [52; 53]. [PERSON] et al. [54] reported that infants that have a slower colonization or a lower number of probiotic enterococci and Bifidobacteria may be more vulnerable to gastrointestinal or allergic problems. Other study by [PERSON] et al. [55] demonstrated that early colonization with Lactobacillus were shown to decrease the effect of allergy. Despite there being no clear protective effect on allergy response reported, breast milk is composed of key players to combat allergy [56; 57]. Another recent systematic study demonstrated that the fecal microbiota of infants with colic found that Bifidobacteria and Lactobacillus were greatly decreased in infants with colic compared to the control infants [58]. Furthermore, the colic phenotype was found to be positively associated with various _Proteobacteria_ groups, but negatively associated with bacteria belonging to the _Firmicutes_ phyla, which includes certain _lactobacillus_ and canonical groups that manufacture butyrate and lactate. Interestingly, some studies have found that administering a _Lactobacillus_ strain believed to be from human milk to infants with infantile colic can be beneficial [58; 59].