Chapter 56, Problem 1Q

Summary Introduction

To analyze:

Show ammonification and Desulfuration of cysteine amino acid.

Introduction:

Ammonification is also known as mineralization and this is the opposite of immobilization. In this process, organic nitrogen has been incorporated into proteins and amino acids. this will be broken down into inorganic nitrogen. Like, suppose any animal and plant has died. So dead organic matter from plant and any other living organism which has died. This dead organic matter decomposes by decomposers like bacteria and fungi. These bacteria and fungi will start the process called decomposition. During the decomposition, this dead organic matter is broken into inorganic matter. From here we get inorganic nitrogen (ammonium ions).

Explanation of Solution

The given amino acid is cysteine, whose molecular formula is C₇H₇NO₂S. Ammonification process of cystine is as follows:

The nitrogen cycle is the process in which the recycling of nitrogen takes place by different organisms. Ammonification is one of the processes of the nitrogen cycle, where bacteria convert the organic nitrogen, such as amino acids and nucleotides from the dead plants and animals to ammonia.

The amino groups on the amino acids are removed by the process of delamination, which results in the production of ammonia. The ammonification process is advantageous to autotrophs that are unable to follow the deamination process. Ammonia gets dissolved in water present in the soil to form ammonium ions, which are then converted to nitrates and nitrites by Nitrobacter and Nitrosomonas.

Desulfuration:

There are some other bacteria, which are involved in another biogeochemical cycle called the sulfur cycle. Desulfuration is a process in the sulfur cycle, where sulfates are reduced by sulfate-reducing bacteria, such as desulfovibrio, to hydrogen sulfide and amino acids that contain sulfur are degraded to produce hydrogen sulfide.

Sulfur-reducing bacteria obtain energy by molecular hydrogen during the process of Desulfuration. They breathe sulfate rather than oxygen. In this way, Desulfuration benefits sulfur-reducing bacteria.

Conclusion

Thus, ammonification where through the dead plant and animals get inorganic nitrogen which is dissolved in water with soil and plants intake ammonium ions easily. Desulfuration is a process in the sulfur cycle, where sulfates are reduced by sulfate-reducing bacteria, such as desulfovibrio, to hydrogen sulfide and amino acids that contain sulfur are degraded to produce hydrogen sulfide.