Shehata Hanan R, Newmaster Steven G
NHP Research Alliance, College of Biological Sciences, University of Guelph, Guelph, ON, Canada.
Department of Microbiology, Faculty of Pharmacy, Mansoura University, Mansoura, Egypt.
Front Microbiol. 2020 Jun 9;11:1095. doi: 10.3389/fmicb.2020.01095. eCollection 2020.
Probiotics are defined as "live microorganisms that, when administered in adequate amounts, confer a health benefit on the host." The diverse health benefits have contributed to rapid increase in probiotic consumption and in the value of probiotic market, valued at USD 46 billion in 2019. For probiotics to be effective, the correct species/strains should be delivered viable in an adequate dose. The most commonly used methods for species/strain identification are DNA based methods including targeted and non-targeted methods (e.g., high-throughput sequencing, HTS). Using different DNA based methods, previous studies reported several cases of non-compliance in probiotic products. The objectives of this study are to evaluate levels of compliance in probiotic products (presence of all declared species/strains, absence of any contaminants or undeclared species, and meeting the declared minimum viable cell count) and to compare the performance of targeted and non-targeted methods in probiotic authentication. To the best of our knowledge, this is the largest study of its kind, testing 182 probiotic products, containing a total of 520 strains, collected from United States and Canada. Using species-specific assays, 11 species could not be detected in ten products. Missing species were in seven products, and in one product, in one product while subsp. was mislabeled as subsp. in another. Additionally, undeclared subsp. was detected in one product. Viable count was determined for 72 samples and was found to be lower than declared in five samples, including one product showing no viable cells. Overall, non-compliance was observed in 15 out of 182 products (8%). Additionally, undeclared species at relative abundance of ∼1-2% were found in 14 products using HTS, however, their presence could not be confirmed using species-specific assays. The results show that targeted PCR based methods enable species and strain level identification. The results also highlight the need to continue to develop strain-specific assays appropriate for use with multi-strain products. True strain-specific assays will enable strain authentication in both single-strain products and multi-strain products to ensure probiotic products meet the label claims and ensure probiotic efficacy.
益生菌被定义为“给予宿主健康益处的活微生物，当给予足够数量时”。其多样的健康益处促使益生菌的消费量迅速增长，益生菌市场价值在2019年达到460亿美元。为使益生菌有效，应提供正确的菌种/菌株，且以适当剂量存活。最常用的菌种/菌株鉴定方法是基于DNA的方法，包括靶向和非靶向方法（如高通量测序，HTS）。使用不同的基于DNA的方法，先前的研究报告了几例益生菌产品不符合规定的情况。本研究的目的是评估益生菌产品的合规水平（所有申报的菌种/菌株的存在情况、不存在任何污染物或未申报的菌种，以及达到申报的最低活菌数），并比较靶向和非靶向方法在益生菌鉴定中的性能。据我们所知，这是同类研究中规模最大的一项，测试了从美国和加拿大收集的182种益生菌产品，共包含520个菌株。使用物种特异性检测方法，在十种产品中未检测到11种菌种。七种产品中缺少申报的菌种，一种产品中缺少申报的菌种，一种产品中缺少申报的菌种，另一种产品中申报的亚种被错误标记为亚种。此外，在一种产品中检测到未申报的亚种。对72个样品进行了活菌计数，发现有五个样品的活菌数低于申报值，其中一个产品未检测到活菌。总体而言，182种产品中有15种（8%）不符合规定。此外，使用高通量测序在14种产品中发现了相对丰度约为1-2%的未申报菌种，然而，使用物种特异性检测方法无法确认它们的存在。结果表明，基于靶向PCR的方法能够进行菌种和菌株水平的鉴定。结果还强调了继续开发适用于多菌株产品的菌株特异性检测方法的必要性。真正的菌株特异性检测方法将能够对单菌株产品和多菌株产品进行菌株鉴定，以确保益生菌产品符合标签声明并确保益生菌的功效。
