Malnutrition

Or, Iron deficiency: An Unmet Global Need

Iron deficiency is the most common and widespread nutritional deficiency in the world, according to the World Health Organization [1]. Iron deficiency is rampant in developing countries and is especially prevalent among young children and pregnant mothers. Young children are particularly at risk due to the large amount of iron required during periods of rapid growth. Similarly, expectant mothers require heightened levels of iron during pregnancy, and if this demand is not met, the transfer of iron to the developing fetus may be affected. This problem even persists after birth, since if an infant is born with insufficient iron, postnatal acquisition of additional iron is typically insufficient to make up this deficit [2].

Iron deficiency has remained relatively persistent over time, despite attempted public health interventions, in large part due to challenges in delivering and distributing health care in resource-poor settings. Current prevention and treatment methods require routine provision of supplies of iron supplements or iron-fortified foods, and such items are difficult to aquire or economically prohibitive for populations at greatest risk of iron deficiency [3]. In addition, many of the iron-enriched foods provided by such programs are usually imported from outside sources instead of grown locally. Our aim is to provide developing populations with an economically and logistically superior alternative to distributing iron-rich foods and supplements, which to date have not met this persistent global need.

Phytate

Phytate is the salt form of phytic acid, also known as inositol hexakisphosphate or IP6. This acid is responsible for the chelation of phosphorous and iron in plant tissues. Only ruminant animals such as cows and sheep produce an enzyme in their rumen that can separate the phosphorous and iron from the phytate. Therefore, humans should limit their intake of phytate as it interferes with the absorption of calcium, iron, and zinc.

Phytase, which has the molecular formula C6H18O24P6, is known as myo-inositol (1,2,3,4,5,6) hexakisphosphate phosphohydrolase. It catalyzes the hydrolysis of phytate, or phytic acid, releasing six phosphate groups from phytate. The dephosphorylation of phytate and the consequent release of phosphate groups from the inositol ring reduces phytate’s mineral binding strength. Consequently, the hydrolysis of phytate increases the bioavailability of iron in the human body.

In animal feed, [7] have engineered transgenic seeds as a novel feed additive for improved phosphorous utilization. They engineered phytase from Aspergillus niger in tobacco seeds, providing a stable and convenient packaging of the enzyme. The phytase enzyme helped release phosphorous from phytate. Taewan Kim, et al. (2005) also attempted to shift the pH profile of the Aspergillus niger phytase in order to enhance its effectiveness inside the stomach as an animal feed additive. They were successful in shifting the pH optimum of one mutant to pH 3.8 demonstrating that it is feasible to improve the function of phytase under stomach pH conditions by rational protein engineering.

The northwestern iGEM team 2012 attempts to clone three phytase genes (Aspergillus niger, Citrobacter braakii, and Escherichia Coli) with constitutive promoters of varying strengths. We are creating an iron probiotic that will utilize E.coli as the host cell for using phytase to breakdown phytic acid. We aim to use our cloned phytase gene as a probiotic for third world countries suffering from iron deficiency. The idea is that we can eventually distribute phytase containing E. Coli to different parts of the developing country so that they can utilize it with their staple food source. In addition, our attempt at increasing the bioavailability of iron is more cost-effective than sending iron supplements since E.coli can continually grow inside the stomach once it is consumed through the food source.

Sources:

1. http://www.who.int/nutrition/topics/ida/en/index.html
2. http://jn.nutrition.org/content/138/12/2523.full
3. http://www.ncbi.nlm.nih.gov/pubmed/11943635
4. http://www.rebuild-from-depression.com/soaking-beans/
5. http://www.nature.com/nbt/journal/v11/n7/abs/nbt0793-811.html
6. http://aem.asm.org/content/72/6/4397.short
7. http://www.nature.com/nbt/journal/v11/n7/abs/nbt0793-811.html