Probiotic bacterial cultures brought to shrimp ponds commonly are composed more often than not of heterotrophic bacteria or a mixture of heterotrophic micro organism and autotrophic nitrifiers. Heterotrophic bacteria are the ones bacteria that normally gain their vitamins from organic sources. The primary source of carbon for those bacteria is carbohydrates. Nitrogen is commonly acquired from the proteins within the natural fabric fed on via the bacteria. Just just like the shrimp, heterotrophic micro organism excrete ammonia as a spinoff of the metabolism of the proteins they devour. Some heterotrophic bacteria, however, are able to utilize ammonia without delay as an opportunity supply of nitrogen.
What does this all should do with C: N ratios? Shrimp feeds used in in depth shrimp ponds generally have at least 35% protein. These feeds do now not comprise a number of carbohydrates. C: N ratios in those feeds typically run around 9:1. The bacteria require about 20 gadgets of carbon according to unit of nitrogen assimilated. With the sort of low C:N ratio inside the feed, carbon is the limiting nutrient for heterotrophic bacteria populations. The bacterial populace will not amplify past a positive point due to the limited availability of carbon. The protein inside the organic detritus materials most of the nitrogen requirement for the heterotrophic bacteria below these occasions, and inorganic ammonia isn’t always applied as a nitrogen supply to any awesome volume.
If the C: N ratio is expanded, both by way of feeding lower protein feeds with a higher percent of carbohydrate, or by adding a carbohydrate supply along with molasses similarly to the normal feed, the elevated availability of carbon permits the heterotrophic bacterial population to eat a higher percentage of the protein within the organic material. This outcomes in a entire digestion of the natural fabric in the pond with the aid of the heterotrophic micro organism. As the C: N ratio will increase, the heterotrophic micro organism resort increasingly to ammonia metabolism to meet their nitrogen necessities. As C: N ratios are elevated even in addition, a factor is reached in which nitrogen, rather than carbon, will become the proscribing nutrient. At this factor, ammonia concentrations should be near zero mg/L in the pond.