QualiSud, Université de Montpellier, Avignon Université, CIRAD, Institut Agro, IRD, Université de la Réunion, 911 avenue Agropolis, 34394 Montpellier Cedex, France.
Center for Food Science and Nutrition, Addis Ababa University, Addis Ababa, Ethiopia.
Food Res Int. 2023 Dec;174(Pt 1):113625. doi: 10.1016/j.foodres.2023.113625. Epub 2023 Oct 27.
Folate (vitamin B9) and cobalamin (vitamin B12) deficiencies potentially affect millions of people worldwide, leading to different pathologies. In Ethiopia, the diet is characterized by high consumption of fermented cereal-based foods such as injera, a good source of folate but not of cobalamin, which is only found in foods of animal origin that are rarely consumed. Some of the bacteria responsible for the fermentation of cereals can synthesize cobalamin, but whether or not fermented cereal food products contain cobalamin remains underexplored. The objective of this study was to assess the folate and cobalamin content of injera collected from various households in Ethiopia at different stages of production. Global (16S rRNA gene sequencing) and specific (real-time PCR quantification of bacteria known for folate or cobalamin production) bacterial composition of these samples was assessed. UPLC-PDA was used to identify the cobalamin to see whether the active or inactive form was present. Surprisingly, teff flour contained 0.8 μg/100 g of cobalamin, most probably due to microbial contamination from the environment and the harvesting process. While fermentation increased the folate and cobalamin content in some households, their levels decreased in others. Conversely, cooking consistently reduced the level of the vitamins. Fresh injera contained, on average, 21.2 μg/100 g of folate and 2.1 μg/100 g of cobalamin, which is high, but with marked variation depending on the sample. However, the form of cobalamin was a corrinoid that is biologically inactive in humans. Injera fermentation was dominated by lactic acid bacteria, with significant correlations observed between certain bacterial species and folate and cobalamin levels. For example, a high proportion of Fructilactobacillus sanfranciscensis, a known folate consumer, was negatively correlated with the folate content of injera. On the contrary, Lactobacillus coryniformis, known for its cobalamin synthesis ability was present in high proportion in the cobalamin-rich samples. These findings highlight the complex interrelationship between microorganisms and suggest the involvement of specific bacteria in the production of folate and cobalamin during injera fermentation. Controlled fermentation using vitamin-producing bacteria is thus a promising tool to promote folate and cobalamin production in fermented food.
叶酸（维生素 B9）和钴胺素（维生素 B12）缺乏症可能影响全球数百万人，导致不同的病理。在埃塞俄比亚，饮食的特点是大量食用发酵的谷类食品，如英吉拉，这是叶酸的良好来源，但不是钴胺素的来源，而钴胺素只存在于动物来源的食物中，这些食物很少被食用。一些负责谷物发酵的细菌可以合成钴胺素，但发酵的谷类食品是否含有钴胺素仍未得到充分探索。本研究的目的是评估从埃塞俄比亚不同家庭在不同生产阶段收集的英吉拉中的叶酸和钴胺素含量。评估了这些样本的细菌总体组成（16S rRNA 基因测序）和特定组成（已知叶酸或钴胺素生产的细菌的实时 PCR 定量）。使用 UPLC-PDA 来鉴定钴胺素，以确定存在的是活性形式还是非活性形式。令人惊讶的是，苔麸面粉含有 0.8μg/100g 的钴胺素，这很可能是由于环境和收获过程中的微生物污染。虽然发酵在一些家庭中增加了叶酸和钴胺素的含量，但在另一些家庭中却降低了。相反，烹饪始终会降低维生素的水平。新鲜的英吉拉平均含有 21.2μg/100g 的叶酸和 2.1μg/100g 的钴胺素，这一含量很高，但取决于样本而有很大差异。然而，钴胺素的形式是一种类咕啉，在人类中没有生物活性。英吉拉发酵主要由乳酸菌主导，某些细菌种类与叶酸和钴胺素水平之间存在显著相关性。例如，高比例的果糖乳杆菌，一种已知的叶酸消费者，与英吉拉中的叶酸含量呈负相关。相反，由于其合成钴胺素的能力而闻名的乳杆菌科乳杆菌以高比例存在于富含钴胺素的样本中。这些发现强调了微生物之间复杂的相互关系，并表明在英吉拉发酵过程中，特定细菌参与了叶酸和钴胺素的生产。因此，使用产生维生素的细菌进行受控发酵是促进发酵食品中叶酸和钴胺素生产的有前途的工具。
