Production of amylase by the intestinal microflora in cultured freshwater fish

Abstract

The amylase‐producing ability of the intestinal microflora in cultured specimens of ayu, carp, channel catfish, Japanese eel and tilapia was determined. Mean viable counts of aerobes and anaerobes ranged from 1·1×106 to 3·7×108 cfu g−1 and from 1·3×103 to 1·6×108 cfu g−1, respectively. Aeromonas spp. and Bacteroidaceae were predominant in four to five fish species. Of 206 strains examined, 65 (31·6%) produced ≥0·01 U amylase ml−1. The percentage of producers differed among families and genera of bacteria and fish species. While 56% of the anaerobes produced amylase, only 20% of the aerobes did. More than 50% of Aeromonas, Bacteroidaceae and Clostridium strains produced amylase efficiently while Acinetobacter, coryneforms, Enterobacteriaceae, Moraxella, Plesiomonas and Streptococcus strains did not. High amylase production (≥0·05 U ml−1) was found in 12 strains, 11 from Aeromonas and one Pseudomonas. The percentage of high amylase producers in Japanese eel was lower than the other four fish (2–30%). These results strongly suggest that the amylase produced by the intestinal microflora play an important role in the digestion of starch in freshwater fish to some extent.

Enzymatic Activities of Intestinal Bacteria Isolated from Farmed <i>Clarias gariepinus</i>

“…This is because the gut microflora in fishes and crustaceans can metabolize several nutrients that the host cannot and can convert them to end products that are beneficial to the host (Suzer et al, 2007;Hoyoux et al, 2009). It has been reported that intestinal microorganisms have a beneficial effect on the digestive process of fish such as in the microbial breakdown of cellulose (Saha and Ray, 1998;Bairagi et al, 2002;Saha et al, 2006;Mondal et al, 2008;Ray et al, 2010), starch (Sugita et al, 1997), protein (Chong et al, 2002;Fu et al, 2005;Silvia et al, 2006) and lipid (Tanu et al, 2012).…”

EFFECT OF COPPER IONS ON GROWTH AND BACTERIAL ABUNDANCE IN THE INTESTINAL TRACT OF RAINBOW TROUT (ONCORHYNCHUS MYKISS) LARVAE

“…Archea, which are normally prolific in Rhopaloides odorabile sponges, were not detected after exposure to Cu 2+ concentration of 19.4 µg l -¹ for 14 days. It is well known that fish harbour the communities of microorganisms in the intestinal tract that also fulfill necessary functions (Sugita et al 1997(Sugita et al , 2002. Correspondingly, xenobiotics that inhibit bacterial abundance and qualitative composition in the intestinal tract of fish larvae, as well as their activities, will have negative effects on food assimilation efficiency and antibacterial abilities against fish pathogens.…”

Evaluation of Gut Associated Extracellular Enzyme-producing and Pathogen Inhibitory Microbial Community as Potential Probiotics in Nile Tilapia, <i>Oreochromis niloticus</i>

“…Several investigators have reported the presence of enzyme producing bacteria in the digestive tract of Oreochromis spp. (Sugita et al, 1997;Bairagi et al, 2002;Saha et al, 2006;Ray et al, 2007;Mondal et al, 2008;Sarkar and Ghosh, 2014;Sasmal and Ray, 2015). The present study is the first one demonstrating adherent bacteria and yeasts on the gut surfaces of Oreochromis niloticus along with antagonistic properties against the potential fish pathogens.…”

“…Previously, GI tract of the Oreochromis spp. have been evaluated in several studies in course of enumerating extracellular enzyme-producing (Sugita et al, 1997;Bairagi et al, 2002;Saha et al, 2006;Ray et al 2007;Sarkar and Ghosh, 2014;Sasmal and Ray, 2015), or pathogenic bacteria (Plumb, 1997;Son et al, 1997;Marathe et al, 2016). Enzymatic potential of gut bacteria isolated from various fish species have been displayed as the likely function that probiotics might accomplish.…”