Aquaculture Waste: Potential Synthesis of Polyhydroxyalkanoates

Abstract

Petroleum-based plastics commonly and widely used on a daily basis are a threat to ecological health as they do not degrade in an ecologically feasible time frame. A class of natural polymers known as polyhydroxyalkanoates (PHAs) represents an up-and-coming alternative to petroleum-based materials, as they share properties similar to those of commodity plastics, such as polyethylene, polystyrene, among others, with the advantage of being biodegradable. PHAs are naturally produced by microorganisms under stress, and various farming practices have been proposed to be used for the synergistic and sustainable production of PHA for commercial purposes. Aquaculture has demonstrated particular potential for the production of PHA; however, a large struggle in commercializing these polymers is in procuring necessary feedstocks for manufacture outside of the laboratory environment. Through the coupling of PHA production and biofloc technology in aquaculture, the impediments to commercial exploitation can be potentially surmounted, while also providing for higher production efficiency in aquafarms. This mini-review covers the basic aspects of biofloc technology applied to aquaculture for the commercial production of PHA in large scale and offers a brief perspective on the next steps associated with the research and implementation of PHA production with biofloc technology.

Polyhydroxyalkanoates for Sustainable Aquaculture: A Review of Recent Advancements, Challenges, and Future Directions

“…strain CL1 containing intracellular PHA. Adapted with permission from ref . Copyright 2021 American Chemical Society.…”

“…A recent development in aquaculture farming practices is the Biofloc system (BFT), which eliminates or minimizes water exchange while maintaining high stocking density. , In this system, farming of aquatic animals and treatment of wastewater occur in the same tank, with the production of microorganisms (i.e., SCPs) as a source of food for the cultured aquatic species. Briefly, microorganisms that are already present in the water are induced to assimilate nitrogenous waste (in the form of unconsumed feed or excrement) by supplementing additional C source (e.g., glucose, molasses, or starch) to the water and/or by using lower protein content aquafeed to increase C/N to 15:1 .…”

“…Simultaneously, the presence of PHA can act as a biocontrol agent and immunostimulant, replacing antibiotics and controlling disease outbreaks. New reports about coupling PHA production with aquaculture practices are promising, as no additional nutrients needed for cultivating PHA-producing SCPs, and there are no concerns about biomass harvesting or downstream solvent extraction and purification. , These new techniques will facilitate PHA feasibility while maintaining sustainable and economical aquaculture.…”

“…Most importantly, PHB content in bioflocs reached a significant 16% . This integration of BFT with PHB production offers a substantial PHB supply to the aquaculture organisms . The use of external SBRs in this context prevents the difficulty in maintaining suitable water quality in typical pond-based BFT systems over time and offers better control of the C/N ratio in the system.…”

Effects of Biopolymers from Cassava Implanted with Rodent Bait on Wistar Rats

“…Since the use of plastics has become such a universal way of life, it is almost impossible to get rid of it. Hence, biodegradable plastics may serve as a promising solution to the over-loaded landfills, making plastic by a renewable source [11][12]. As a result of the adverse effects of plastic wastes regarding their impacts in the environment, there is the need to adopt an eco-friendly technology that is capable of producing plastics that are biodegradable, less hazardous to man and the environment.…”