Aquafeed Formulation Using Plant Feedstuffs: Prospective Application of Fish-Gut Microorganisms and Microbial Biotechnology

Improving feed efficiency and disease resistance are already priorities to sustain intensive fish production. Increasing demand, high price, and supply fluctuations of fish meal has emphasized the need to look for alternative protein sources in aquafeeds, the majority of which are diverse plant ingredients. Presence of endogenous antinutritional factors (ANFs), for example, protease inhibitors, tannin, mimosine, phytic acid, nonstarch polysaccharides, and deficiency in some essential amino acids are known to reduce the nutritional value of plant feedstuffs. On the other hand, use of antibiotics in feed to control disease outbreak has been criticized for likely development of antibiotic resistance among pathogenic bacteria. Gut microorganisms capable of producing ANF-degrading enzymes and antibacterial compounds are expected to assist in the continued development and improvement of aquaculture in a sustainable and ecofriendly way. Bioprocessing of the plant feedstuffs through solid-state-fermentation by ANF-degrading microorganisms has been viewed as an effective strategy in some of the recent investigations. Furthermore, applications of the beneficial gut microorganisms as probiotics has been demonstrated to hold promise to antagonize pathogens and also to improve feed efficiency. Collectively, this chapter provides a summary of findings on application of conventional methods, as well as bioprocessing strategy adopted for deactivation of endogenous ANFs, and also use of probiotics as biocontrol agents to consider application of microbial biotechnology in formulation of aquafeeds.