The impact of storage conditions on the stability of Lactobacillus rhamnosus GG and Bifidobacterium animalis subsp. lactis in breast milk
Mantziari, Anastasia (2016-09-14)
The impact of storage conditions on the stability of Lactobacillus rhamnosus GG and Bifidobacterium animalis subsp. lactis in breast milk
Mantziari, Anastasia
(14.09.2016)
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Turun yliopisto
Kuvaus
Siirretty Doriasta
Tiivistelmä
Breast milk is the optimal source of nutrition for neonates and is also a continuous source of beneficial microbes that are important for the development of infant gut microbiota and maturation of immune system. In some cases, breast milk can be supplemented with probiotics to complement the health benefits of breastfeeding. For instance, probiotic supplementation can reduce the risk of necrotizing enterocolitis, which is the main cause of mortality in pre-term infants. Storage of breast milk for limited periods of time is often unavoidable, but little is known about how storage conditions affect the breast milk microbiota and viability of probiotics. Therefore, we evaluated in the present study how different storage conditions affect the viability of two widely used probiotics, Lactobacillus rhamnosus GG and Bifidobacterium animalis subsp. lactis Bb12, in breast milk.
Pooled breast milk samples were used as the study matrix. The breast milk was divided into three groups: 1) supplementation with ~1x108 cfu/ml L. rhamnosus GG; 2) ~1x108 cfu/ml B. animalis subsp. lactis Bb12; and 3) no supplementation. The samples were stored at room temperature for 6 hours, at +4οC for 6, 24 and 72 hours and at -20οC for seven days after which the bacterial counts were enumerated by culturing and quantitative polymerase chain reaction. The presence of L. rhamnosus GG or B. animalis subsp. lactis Bb12 was confirmed by extracting DNA from isolated colonies and using polymerase chain reaction coupled with strain-specific primers. In addition, the colonies from no supplementation group were isolated for identification. Next, bacterial DNA from the milk samples was extracted and used for quantitative PCR to confirm these results. All experiments were conducted in triplicate.
Overall, there were no significant differences in the viable cell counts of probiotics between the different time points. Our results indicate that L. rhamnosus GG and Bb12 remained stable during the study period. Thus, we conclude that breast milk could be an appropriate matrix for probiotic supplementation. This work serves as a basis for future studies on the stability of probiotics in human breast milk.
Pooled breast milk samples were used as the study matrix. The breast milk was divided into three groups: 1) supplementation with ~1x108 cfu/ml L. rhamnosus GG; 2) ~1x108 cfu/ml B. animalis subsp. lactis Bb12; and 3) no supplementation. The samples were stored at room temperature for 6 hours, at +4οC for 6, 24 and 72 hours and at -20οC for seven days after which the bacterial counts were enumerated by culturing and quantitative polymerase chain reaction. The presence of L. rhamnosus GG or B. animalis subsp. lactis Bb12 was confirmed by extracting DNA from isolated colonies and using polymerase chain reaction coupled with strain-specific primers. In addition, the colonies from no supplementation group were isolated for identification. Next, bacterial DNA from the milk samples was extracted and used for quantitative PCR to confirm these results. All experiments were conducted in triplicate.
Overall, there were no significant differences in the viable cell counts of probiotics between the different time points. Our results indicate that L. rhamnosus GG and Bb12 remained stable during the study period. Thus, we conclude that breast milk could be an appropriate matrix for probiotic supplementation. This work serves as a basis for future studies on the stability of probiotics in human breast milk.