Scientists have called new discoveries from leading Japanese dairy product company Morinaga Milk Industry on popular probiotic genus bifidobacteria, “an interesting first step”.
Morinaga Milk said recently that its latest research indicates that bifidobacteria found in human intestines and bifidobacteria from other sources have different capabilities.
Bifidobacteria are the predominant bacteria living in the gastrointestinal tract of a healthy human being and are also found elsewhere – non-human residential bifidobacteria, or nHRB.
Tokyo-based Morinaga Milk, which offers products such as functional foods and infant formulas, has researched bifidobacteria for more than 40 years.
It recently investigated the potential capabilities of HRB and nHRB from genomic information, and validated the actual capabilities by performing in vitro and animal experiments.
Results were presented in March this year at the Annual Meeting of the Japan Society for Bioscience, Biotechnology and Agrochemistry.
Morinaga Milk said its first study, Comparative Genomic Analysis, compared the genomes of a total of 68 strains belonging to 12 species of Bifidobacterium, including the publicly available genome sequences as well as newly analysed genome sequences.
The results indicated differences in conserved gene clusters specific to habitats. Detailed analysis was performed on three species which are commercially used as probiotics in the market [HRB: B. longum (subsp. longum and subsp. infantis) and B. breve; nHRB : B. animalis (subsp.animalis and subsp. lactis)]. Comparing these HRB with nHRB highlighted differences, suggesting that HRB is superior to nHBR.
Morinaga Milk scientists concluded that HRB can produce more vitamins compared to nHRB and HRB differ from nHRB in the ability to colonise the intestinal tract. And HRB is superior to nHRB in responding to rapid environmental changes.
Morinaga Milk’s next study examined compatibility with human breast milk, looking at whether the differences predicted from the genome are reflected in actual functions.
International probiotic microbiology consultant Mary Ellen Sanders told NutraIngredients the findings should be treated cautiously.
“Research that identifies health-promoting functions attributed to specific species of bifidobacteria may be useful for targeting the best candidate probiotics.”
“The authors present results that suggest the hypothesis that some desirable attributes may be present in certain Bifidobacterium species but not in others. In my opinion, however, this research overextends conclusions to a category – i.e. bifidobacterium species not naturally found in humans – based on findings from strains of only one such species, B. animalis. The findings may be specific to B. animalis, not to all nHRB. But it’s an interesting first step.”
Various bifidobacterial strains were inoculated into human breast milk donated by healthy mothers, and cultured at 37 degreesC. The results clearly showed that while most of the HRB (B. longum, B. breve and B. infantis) isolated from infants grew well in breast milk, nHRB failed to grow and even died out after overnight incubation in the breast milk.
In addition, Morinaga confirmed that resistance to lysozyme, an antibacterial active substance that exists in breast milk, is also involved in the selective growth of bifidobacteria in breast milk. HRB are tolerant to lysozyme but nHRB are highly susceptible to lysozyme.
A third study on the difference in folate production capability examined the in vitro folate production capability of various bifidobacterial strains. High folate concentrations were detected in the culture media of HRB, compared with nHRB.
Further studies were conducted using germ-free mice by mono-associating with B. longum (subsp. longum), B. breve, and B. animalis (subsp. lactis). In mice mono-associated with HRB, especially with B. longum, fecal folate concentrations were higher and hematological indicators related to anemia were improved as compared to nHRB. Since folate is related to anemia prevention, it is possible that intestinal folate levels affect hematological indicators, researchers said.
Morinaga Milk says that the results obtained from its studies indicate that HRB may be more compatible with infant intestines and potentially more beneficial to the hosts.
“We were quite surprised at the result of the study on the compatibility with mother’s breast milk, which showed that nHRB could not grow in the breast milk," said Jin-zhong Xiao, PhD, department manager of Food Science & Technology Institute, biological function research department at Morinaga Milk Industry.
"It has been suggested that the selective growth of bifidobacteria observed in breastfed newborn infants is related to the Human Milk Oligosaccharides (HMOs) in human milk, however, in the in vitro experiments for growth in breast milk, undigested lactose should be sufficient for growth of Bifidobacterium even without assimilating HMOs.”
“The fact that HRBs possess high compatibility with human breast milk suggests how natural and more suitable HRBs are for consumption by human and infants."
Sophie Pauk, global food science analyst at Mintel commented: “More studies are revealing that not all probiotics have the same impact. As research continues to explore the complex nature of the human microbiota, it will bring focus and interest about the ways consumers can support and develop a healthy microbiota.”
The genus Bifidobacterium is classed into more than 40 species or subspecies but the differences among each species are not well understood.