Nowadays, more than 40% of global shrimp production comes from aquaculture. The major economic losses in shrimp aquaculture are because of mass mortality, slow growth, and deformity of shrimp body (Mine & Boopathy, 2011). Globally recorded mass mortalities of shrimp might come from viral and bacterial pathogens infection in their body (Mine & Boopathy, 2011). Many people use antibiotics to prevent these issues. However, continuously feeding shrimp with antibiotics for therapeutic or growth promotion will cause antibiotic-resistant bacteria. These usages of organic acid in aquaculture already proven by some studies are effective to suppress pathogenic bacterial growth in gastrointestinal tracts of poultry and swine (Franco et al., 2005).
Some bacterial diseases in shrimp aquaculture because of an infection of Vibrio species which is called as vibriosis. Vibrio infection is thought to spread into the body via the pit, puncture wounds, the exoskeleton and oral intake. Vibrio species are ubiquitous in the estuarine and marine environment. However, the common Vibrio species found in shrimp hatchery, nursery and grow out is Vibrio harveyi, Vibrio vulnificus, Vibrio parahaemolyticus and Vibrio alginolyticus (Adams & Boopathy, 2013). According to Chuchird et al., 2015 recorded Vibrio parahaemolyticus causes mass mortality as it induces 100% mortality in shrimp. To overcome this problem we can use organic acid to reduce the amount of vibrio infection instead of using antibiotics or probiotics in our aquaculture.
( Formic acid and Pallet at Shrimp Farm )
As I mentioned before, reducing the amount of antibiotics usage in shrimp can substitute with organic acids because they have the potential to control pathogens in animal husbandry. Organic acids are naturally metabolic products by organisms. Besides, it has the ability to become alternatives to antibiotics in aquaculture (Adams & Boopathy, 2013) because it has antibacterial properties against a variety of harmful bacteria including Vibrio species (Rickie, 2013). There are many types of organic acid that have been tested to control or reduce the growth of vibrio in aquacultures such as acetic acid, propionic acid, butyric acid, formic acid and benzoic acid. Even so, not all organic acids are effective to inhibit bacteria or Vibrio species. Among all this, some studies said the most effective to inhibit the growth of Vibrio species is formic acid in shrimp (Mine & Boopathy, 2011; Adams & Boopathy, 2013; Chuchird et al., 2015). The previous study, have been recorded formic acid at low concentration (0.07%) able to completely inhibit the growth of Vibrio harveyi and other Vibrio species (Mine & Boopathy, 2011). However, it still needs more research about organic acid on shrimp.
Furthermore, organic acids are a chemical that consists of molecules that are not dissociated into oppositely charged ions which easily enter bacterial cell membranes and break up the compound into anions and H+ in the cytoplasm (Chuchird et al., 2015). They will lower the pH value and damage the cytoplasmic membrane, protein synthesis system, genetic material, and metabolic enzymes once they enter the bacterial cells (Chuchird et al., 2015). In addition, organic acid affects the cell’s ability to maintain pH at neutral by decreasing energy level, due to bacterial cells needing the energy to pump excess H+ out of cells (Chuchird et al., 2015). Hence, by the process, Vibrio species cannot reproduce and it reduces or inhibits the growth of Vibrio species directly.
In summary, we may apply the use of organic acid as an alternative to pathogen control in shrimp aquaculture. Antibiotic resistance will develop as a result of excessive usage of antibiotics, which will affect our ecosystem. Many organic acids have been studied, but formic acid has proven to be the most inhibiting pathogens even at low doses. However, the use of organic acid in shrimp farming is not fully established yet.
References
Adams, D., & Boopathy, R. (2013). Use of formic acid to control vibriosis in shrimp aquaculture. Biologia, 68(6), 1017-1021.
Chuchird, N., Rorkwiree, P., & Rairat, T. (2015). Effect of dietary formic acid and astaxanthin on the survival and growth of Pacific white shrimp (Litopenaeus vannamei) and their resistance to Vibrio parahaemolyticus. SpringerPlus, 4(1), 1-12.
Franco, L. D., Fondevila, M., Lobera, M. B., & Castrillo, C. (2005). Effect of combinations of organic acids in weaned pig diets on microbial species of digestive tract contents and their response on digestibility. Journal of Animal Physiology and Animal Nutrition, 89(3‐6), 88-93.
Mine, S., & Boopathy, R. (2011). Effect of organic acids on shrimp pathogen, Vibrio harveyi. Current microbiology, 63(1), 1-7.
Ricke, S. C. (2003). Perspectives on the use of organic acids and short chain fatty acids as antimicrobials. Poultry science, 82(4), 632-639.