Use of bacterial subcellular components as immunostimulants in fish aquaculture

Abstract

Aquaculture and fisheries products are expected to play a leading part in addressing the food necessities of the increasing human population. However, in intensive aquaculture, fish are exposed to stress conditions that deteriorate their immune systems, leading to increased disease vulnerability. These disease outbreaks have resulted in production losses and represent one of the key constraints in fish farming. Accordingly, aquaculture disease management efforts have concentrated on the establishment of environmental friendly and lasting methods. Recently, several studies have revealed that various bacteria (especially probiotics)‐derived cellular components might be used as promising immunostimulants in fish aquaculture. Such components curtail the risk concomitant with the use of antibiotics, chemotherapeutics, vaccines and probiotics. Among the various health advantages ascribed to bacterial cellular components, the modulation of specific and nonspecific immune responses, cytokine gene expression and anti‐pathogenic activities are most anticipated benefits. Their potential as vaccine adjuvants for fish culture has also been demonstrated. However, as an emerging practice, limited knowledge is available regarding the detailed interactions with fish immune systems. Therefore, the underlying mechanisms involved in fish immune cell activation need to be explored further. In this context, the present article aspires to review the available studies on the use of bacterial cellular components in fish culture and their biological effects on fish such as growth promotion, immunostimulation and anti‐pathogenic activities as well as to evaluate the factors that control the optimal induction of immune responses in fish. In addition, future issues that merit further investigation are suggested.

Effects of Lactobacillus acidophilus and tussah immunoreactive substances on disease resistance of sea cucumber ( Apostichopus japonicus ) against Vibrio splendidus

“…Immunostimulants are biosynthetic compounds which can enhance the nonspecific cellular and humoral defences of aquatic animals (Dawood et al, 2018;Giri et al, 2016;Mohan et al, 2018).…”

“…Immunostimulants are biosynthetic compounds which can enhance the nonspecific cellular and humoral defences of aquatic animals (Dawood et al, 2018; Giri et al, 2016; Mohan et al, 2018). Tussah immunoreactive substances (TIS), which were first obtained from the pupal haemolymph of the Chinese oak silkworm Antheraea pernyi , possess various antibacterial activities, and participate in the removal of invading microorganisms (Huang & Wang, 1981).…”

Role of Bacillus licheniformis VS16-Derived Biosurfactant in Mediating Immune Responses in Carp Rohu and its Application to the Food Industry

“…However, intensive aquaculture practices result in stress, poor water quality, poor nutritional status, overcrowding, and sudden changes in temperature. Further, widespread industrial developments have caused deteriorated aquatic environments (Giri et al, 2016a). Typically, antibiotics and chemotherapeutics are used to control diseases in aquatic animals.…”

Laboratory and Field Assessments of Oral Vibrio Vaccine Indicate the Potential for Protection against Vibriosis in Cultured Marine Fishes

“…Moreover, since bacterial extracts have been shown to stimulate innate immunity in fish and potentially act as an immunostimulant, it may contribute to the rise of immunoglobulin levels. Giri et al [ 33 ] reported that the rise in immunoglobulin levels is a short-term phenomenon attributable to immunostimulants. Due to the vaccine being at its early development and the current study only wanting to observe its early responses, further study needs to be conducted to determine whether the oral vaccine could provide longer-term protection to the fish.…”