In situ biofortification of folate in sorghum with Lactobacillus plantarum and its microbiome analysis using 16s rRNA gene sequencing

Abstract

Folate deficiency is an unfortunate reality in South Africa. Folate (vitamin B9) is important for many cellular pathways in the body, one of which is the prevention of neural tube defects (NTD’s) during pregnancy. We cannot synthesise folate ourselves and therefore we rely on exogenous sources such as our diets to obtain folate. Folate is found in a variety of sources such as green leafy vegetables, legumes, fortified foods and even dietary supplements. Even though supplements can prevent folate deficiencies, the high folate content in the blood plasma caused by synthetic folate can mask a vitamin B12 deficiency. The objective of this study was to ferment sorghum with folate producing Lactobacillus plantarum with the aim of increasing the folate content through in situ biofortification. The application of four L. plantarum strains (FS2, B411, S7 and S49) as starter cultures in fermented sorghum were successfully used to biofortify these fermentations with folate. The use of L. plantarum B411 and FS2 generated a folate increase of 50% or more from the spontaneous fermentation. Furthermore, it was found that the addition of 10% sorghum malt had a significant effect on the folate content of the sorghum fermentations. The sorghum malt contained enzymes, such as α-amylase, that are capable of promoting growth of microorganisms, such as folate producing L. plantarum. Sorghum fermented with L. plantarum B411 and sorghum malt had a folate content of 31.82 µg per 100ml fermentation. This is a 118% increase from the spontaneous fermentation. Sorghum fermented with L. plantarum FS2 and sorghum malt had a folate content of 30.39 µg per 100ml fermentation. This is a 109% increase from the spontaneous fermentation. These two L. plantarum strains will be ideal to use as starter cultures in sorghum fermentations to increase their folate content through biofortification. The application of these starter cultures could potentially be patented and used to commercialise high folate fermentations. The microbiomes of the sorghum fermented with L. plantarum alone were also analysed through 16S rRNA gene sequencing with the aim of establishing a base microbiome and determining whether these microbiomes share any similarities. The microbiomes gave insight into the microbial communities of these fermentations and revealed that they were dominated by Lactobacillus. Lactobacillus was responsible for the fermentation process and hence would serve well as starter cultures for these fermentations. In addition, the microbiomes of two South African and two Nigerian fermentations were analysed with the aim of identifying a potential starter culture and to create a reference microbiome for future studies. The microbiome of sorghum spontaneously fermented for 24h was successfully determined and can be used as a reference microbiome in future studies. The sorghum fermentations produced in a laboratory (South Africa) were dominated by Paenibacillus after 24h and Clostridium sensu_stricto_11, and other unidentified genera, after 72h. The microbiomes of the maize and sorghum fermentations sourced from a Nigerian market were dominated by Lactobacillus and appeared similar. Lactobacillus was present in all fermentations and therefore there is potential in the use of Lactobacillus as a starter culture in sorghum fermentations