Characterization of the indigenous microflora in raw and pasteurized buffalo milk during storage at refrigeration temperature by high-throughput sequencing

Authors: LI, LING - Chinese Academy Of Agricultural Sciences; Renye, John; ZENG, QINGKUN - Chinese Academy Of Agricultural Sciences; HUANG, LI - Chinese Academy Of Agricultural Sciences; REN, DAXI - Zhejiang University; TANG, YAN - Chinese Academy Of Agricultural Sciences; YANG, PAN - Chinese Academy Of Agricultural Sciences

Submitted to: Journal of Dairy Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/24/2016
Publication Date: 6/29/2016
Citation: Li, L., Renye Jr, J.A., Zeng, Q., Huang, L., Ren, D., Tang, Y., Yang, P. 2016. Characterization of the indigenous microflora in raw and pasteurized buffalo milk during storage at refrigeration temperature by high-throughput sequencing. Journal of Dairy Science. 99:7016-7024. doi: 10.3168/jds.2016-11041.

Interpretive Summary: The bacteria in raw buffalo milk remains largely uncharacterized and has the potential to affect the quality and safety of dairy foods. This study utilized molecular techniques to characterize bacteria in raw and pasteurized buffalo milk stored at refrigeration temperature. Results showed that lactic acid bacteria dominated the microbial community at 24 hours and 7 days in raw and pasteurized milk, respectively, while spoilage bacteria were dominant in raw and pasteurized milk stored for 72 hours and 14 days, respectively. The predominant spoilage bacteria differed in raw and pasteurized milk suggesting a need for unique strategies to control contaminant growth.

Technical Abstract: The effect of refrigeration on bacterial communities within raw and pasteurized buffalo milk was studied using high-throughput sequencing. High quality samples of raw buffalo milk were obtained from five dairy farms in the Guangxi province of China. A sample of each milk was pasteurized, and both raw and pasteurized milks were stored at refrigeration temperature for various times with microbial communities characterized using the Illumina Miseq platform. Results showed that both raw and pasteurized milks contained a diverse microbial population and that the populations changed over time during storage. In raw buffalo milk, Lactococcus and Streptococcus dominated the population within the first 24h; however when stored for up to 72 hours the dominant bacteria were members of the Pseudomonas and Acinetobacter genera totaling more than 60% of the community. In pasteurized buffalo milk, the microbial population shifted from a Lactococcus dominated community (7 days), to one containing more than 84% Paenibacillus by 21 days of storage. In order to increase the shelf-life of buffalo milk and its products, raw milk should be monitored for the presence of Paenibacillus, and pasteurization should be performed within 24 hours of raw milk collection when the number of psychrotrophic bacteria are low. Since Paenibacillus spores are resistant to pasteurization, additional antimicrobial treatments may be required to extend shelf-life. The findings from this study are expected to aid in improving the quality and safety of raw and pasteurized buffalo milk.