Distribution of enzyme-producing bacteria in the digestive tracts of some freshwater fish

Abstract

Mondal S., Roy T., Sen S.K., Ray A.K. 2008. Distribution of enzyme-producing bacteria in the digestive tracts of some freshwater fish. Acta Ichthyol. Piscat. 38 (1): 1-8.Background. The information on gut microflora in fish is scanty and there is a paucity of knowledge regarding microbial enzyme activity in fish gastrointestinal tracts. Although some information is available on the enzymeproducing bacteria in fish digestive tracts, almost nothing is known about their distribution in different regions of the gut. In the present study, an attempt has been made to investigate the distribution of enzyme-producing microflora in the foregut and hindgut regions of seven culturable freshwater teleosts. Materials and Methods. Isolation and enumeration of aerobic bacterial flora in the foregut and hindgut regions of the gastrointestinal tracts of seven freshwater teleosts of different feeding habits, namely rohu, Labeo rohita; catla, Catla catla; mrigal, Cirrhinus mrigala; bata, Labeo bata; orange-fin labeo, Labeo calbasu; Nile tilapia, Oreochromis niloticus; and climbing perch, Anabas testudineus, have been carried out. Microbial culture of the gut mucosa on selected nutrient media, following the enrichment culture technique, was done for bacterial isolation. Bacterial isolates were qualitatively screened on the basis of their extracellular enzyme-producing ability. The selected strains were further quantitatively assayed for amylase, cellulase and protease activities.Results. In general, bacterial population was lower in the foregut region of all the seven species of fish examined. Amylolytic strains were present in higher densities in the foregut region of orange-fin labeo and bata (12.20 × 10 3 CFU · g -1 gut tissue and 11.50 × 10 3 CFU · g -1 gut tissue, respectively) in comparison to the hindgut region. The cellulolytic population exhibited maximum densities in the hindgut region of bata (7.20 × 10 3 CFU · g -1 gut tissue) followed by the foregut region of the same fish (5.50 × 10 3 CFU · g -1 gut tissue). Amylolytic and cellulolytic bacterial flora was not detected in both the fore and hindgut regions of climbing perch. Proteolytic bacterial flora was found in all the species of fish studied and the maximum count was observed in the hindgut region of bata (13.40 × 10 3 CFU · g -1 gut tissue), orange-fin labeo (9.00 × 10 3 CFU · g -1 gut tissue), Nile tilapia (8.30 × 10 3 CFU · g -1 gut tissue) and climbing perch (7.20 × 10 3 CFU · g -1 gut tissue). Minimum count of proteolytic bacterial flora was observed in the foregut region of all the fishes studied. Peak amylase and cellulase activities were exhibited by bacterial strains isolated from the foregut of orange-fin labeo (266.43 ± 0.15 U) and the hindgut of bata (64.01 ± 0.42 U), respectively. Maximum protease activity was exhibited by a strain isolated from the hindgut region of orange-fin labeo (44.33 ± 0.09 U), followed by the strains isolated from the hindgut regions of climbing perch (32.87 ± 0.12 U), bata (29.71 ± 0.11 U), and Nile tilapia (29.46 ± 0.11 U). C...

Selection and probiotic characterization of exoenzyme-producing bacteria isolated from the gut of Catla catla (Actinopterygii: Cypriniformes: Cyprinidae)

“…Although, gut bacteria in catla were noticed to be dominated by the cellulolytic bacteria, existence of lipolytic, amylolytic, and proteolytic bacteria clearly advocated omnivorous feeding aptitude of the species as suggested elsewhere (Dasgupta 1996, Ghosh et al 2002a, Khabade 2015. Occurrence of higher numbers of heterotrophic enzyme-producing bacteria in DI region compared to the PI region was in agreement with the previous reports (Mondal et al 2008, Das et al 2014. This might indicate the possibility of microbial degradation of the food material in this part of the GI tract in assistance with the highly colonized enzyme-producing bacteria (Ghosh et al 2010).…”

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

“…In the present investigation, considerable populations of amylolytic and proteolytic bacteria were detected, which was in agreement with Mondal et al (2008) who reported amylolytic and proteolytic bacteria in the gastrointestinal tract of Nile tilapia correlating to its omnivorous feeding aptitude. Bairagi et al (2002) isolated an efficient protease-producing strain, TP3A from the gut of Oreochromis mossambica.…”

“…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.…”

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).…”