New metabolic pathways are found in rumen microbiome

Cows can adapt themselves to a fluctuating sodium content in their feed. How they do that was so far a secret.

New metabolic pathways are found in rumen microbiome, A cow can only grow grass in its stomach with the help of billions of microorganisms. All zoo bacteria, archaea and the most common work there as a production line.

First, these unicellular organisms break down polysaccharide cellulose. Other bacteria fermenting sugar is released in fatty acids, alcohols and gases such as hydrogen and carbon dioxide. Finally, methanogenic archanea converts these two gases into methane.

The average cow produces about 110 liters of methane a day. Extracted from the mouth through the rumen, but also mixed again with partially digested food. As a result, the sodium content of the yard can fluctuate significantly (between 60 and 800 millimoles of sodium chloride (NaCl) per liter).

Respiratory circuits contain the Fd: NAD + oxidoreductase (Rnf complex) enzyme complex. It uses energy to transport sodium ions out of the cell. When re-entering the cell, sodium ions trigger ATP synthase to produce ATP. This respiratory chain only functions in the presence of sodium ions.

In the absence of sodium ions, bacteria form alternative respiratory chains with other enzyme complexes: Ech hydrogenase (synonym: Fd: H + oxidoreductase) produces hydrogen and pumps protons out of the cell.

When they return to the cell via the second ATP synthase which accepts protons but no sodium ions, ATP is produced.

This is the first bacterium to have two simple and very different breathing circuits. However, our bioinformatic tests show that they also exist in other bacteria.

Interestingly, both enzyme complexes (Rnf and Ech) are found in old bacteria in evolutionary biology.

With synthetic microbiological methods, we will now produce hybrid bacteria that contain both complexes to optimize them for biotechnology processes. In this way, we can improve cellular ATP content, which allows us to produce high-quality products.

Valuable substances must be recovered through gas synthesis through the respiratory tract.

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