Extracellular tannase-producing bacteria detected in the digestive tracts of freshwater fishes (Actinopterygii: Cyprinidae and Cichlidae)

Abstract

Talukdar S., Ringø E., Ghosh K. 2016. Extracellular tannase-producing bacteria detected in the digestive tracts of freshwater fi shes (Actinopterygii: Cyprinidae and Cichlidae). Acta Ichthyol. Piscat. 46 (3): 201-210.Background. Although, presence of tannase-producing and/or tannin tolerant gut bacteria has been documented in ruminants and non-ruminant herbivores, the topic is rarely addressed in fi sh. The present study aimed at enumeration of autochthonous tannase-producing bacteria in the gut of freshwater teleosts. Gastrointestinal (GI) tracts of the fi sh studied were divided into proximal (PI) and distal (DI) parts, homogenized and plated onto Tryptone Soya Agar (TSA) plates. The pure colonies were spotted on selective tannic acid (TA) agar plates to determine the tannase-producing bacteria. Extracellular tannase-producing capacity of the isolates was determined through qualitative and quantitative assay using TA media plates or broth, respectively at three different pH levels (5.5, 7.0, and 8.5). Further, 16S rRNA gene fragments of the promising tannase-producing bacteria were sequenced, aligned, analysed, identifi ed, and deposited to the GenBank. Results. Totally 685 strains were isolated on TSA plates, of which 116 strains (37 from PI and 79 from DI) grow on TA media and were defi ned as tannase-producers. The highest percentage of tannase-producing strains was noticed in the DI regions of grass carp, Ctenopharyngodon idella (38.98%), and tilapia, Oreochromis niloticus (37.74%). The lowest frequency of tannase-producing bacteria was revealed in PI region of catla, Catla catla (2.12%). The intestine of Indian major carps was relatively poorly colonized by tannase-producing bacteria compared to that of exotic carps. Evaluation of tannase-producing capacity revealed that the majority of the isolates exhibited maximum extracellular tannase production at pH 7.0. Quantitative evaluation, showed highest tannase activity by strain HMT1 (0.28 ± 0.001 U) isolated from silver carp, Hypophthalmichthys molitrix, followed by strains ONH2Ph (0.19 ± 0.005) and ONH13B (0.17 ± 0.009 U) isolated from tilapia. Analyses of the 16S rRNA partial gene sequences revealed that strains ONH2Ph and ONH13B showed high similarity to Bacillus subtilis (KP765736) and Brevibacillus agri (KP765734), respectively. Whereas, strain HMT1 was most closely related to Klebsiella variicola (KP765735). Conclusions. The study revealed existence of tannase-producing bacterial symbionts within fi sh GI tracts. Tannindegrading bacteria detected in the presently reported study might aid in overcoming the anti-nutritional effects of dietary tannins within fi sh gut.

Applications of plant ingredients for tropical and subtropical freshwater finfish: possibilities and challenges

“…; Khan & Ghosh ; Das & Ghosh ) and tannin (Mandal & Ghosh ,b; Talukdar et al . ). Therefore, an extensive range of enzymes like carbohydrases, phosphatases, esterases, lipases and peptidases, cellulase, lipase and proteases produced by GI bacteria may contribute to the digestive processes in fish.…”

“…More recently, tannase‐producing Bacillus subtilis (KP765736), Brevibacillus agri (KP765734) and Klebsiella variicola (KP765735) have been revealed in the GI tracts of freshwater teleosts (Talukdar et al . ). In this study, highest percentage of tannase‐producing strains was noticed in the distal regions of the GI tracts in diverse carp species and Nile tilapia.…”

A review of intestinal microbes in grass carpCtenopharyngodon idellus(Valenciennes)

“…Cellulase‐producing microbes, such as Anoxybacillus , Leuconostoc , Clostridium , Actinomyces , Aeromonas , Citrobacter , Streptococcus , Enterobacter , Plesiomonas , Brevibacterium , Bacillus , Enterococcus , Raoultella , Klebsiella , Hydrotalea , Pseudomonas and Brevibacillus , are abundant in the intestinal tract of grass carp (Jiang et al., ; Li et al., ; Liu et al., ; Saha, Roy, Sen & Ray, ; Wang et al., ; Wu, Wang et al., ). Besides, the microbial communities producing enzymes (starch‐hydrolysing, proteolytic, tannase and phytase) and lactic acid bacteria are also found in the grass carp intestine (Mandal & Ghosh, ; Roy et al., ; Shi et al., ; Shivokene‐Ya & Grigorovich, ; Shivokene‐Ya & Yankyavichyus, ; Talukdar et al., ). Some genera, like Aeromonas , Vibrio and Bacillus, are able to produce other digestive enzymes, such as protease, lipase and amylase, throughout the grass carp intestine (Feng et al., ).…”

“…This colonization begins during the egg and/or larval stages and continues during all subsequent developmental stages (Li, Zhong et al., ; Olafsen, ; Wang, Wu et al., ; Zhu et al., ). The substantial literature on the intestinal microbiota of grass carp has been conducted in association with the microbial isolation and identification (Dang & Dalsgaard, ; Hatha, Kuruvilla & Cheriyan, ; Miller & Gibson, ; Pan et al., ; Zeng & Yuan, ), their enzymatic ability and nutritional aspects (Bairagi, Ghosh, Sen & Ray, ; Banerjee & Ghosh, ; Feng et al., ; Li et al., ; Mandal & Ghosh, ; Rajasekaran, Sivakumar & Mathialagan, ; Roy, Mondal & Ray, ; Shi et al., ; Talukdar, Ringø & Ghosh, ; Wang, Zhu et al., ), studies on pathogenic aspects (Lü et al., ; Xu, Ge & Xiong, ; Xu, Xiong, Han, Lu & Ge, ), antibiotic resistance (Hatha, Vivekanandhan, Julie Joice & Christol, ) and vaccination application (He et al., ; Liu et al., ). Recently, studies regarding the diversity of bacterial communities in the intestine of grass carp, as well as the effects of external factors (feed, prebiotics and probiotics) on intestinal microbial populations, have been published (Li, Zhong et al., ; Wang, Wu et al., ; Wu, Wang et al., ; Wu, Feng et al., ).…”

“…identification (Dang & Dalsgaard, 2012;Hatha, Kuruvilla & Cheriyan, 2000;Miller & Gibson, 2011;Pan et al, 2005;Zeng & Yuan, 1999), their enzymatic ability and nutritional aspects (Bairagi, Ghosh, Sen & Ray, 2002;Banerjee & Ghosh, 2014;Feng et al, 2008;Li et al, 2014;Mandal & Ghosh, 2013;Rajasekaran, Sivakumar & Mathialagan, 2014;Roy, Mondal & Ray, 2009;Shi et al, 2008;Talukdar, Ringø & Ghosh, 2016;Wang, Zhu et al, 2015), studies on pathogenic aspects (L€ u et al, 2011;Xu, Ge & Xiong, 1988;Xu, Xiong, Han, Lu & Ge, 1987), antibiotic resistance (Hatha, Vivekanandhan, Julie Joice & Christol, 2005) and vaccination application (He et al, 2007;Liu et al, 2015). Recently, studies regarding the diversity of bacterial communities in the intestine of grass carp, as well as the effects of external factors (feed, prebiotics and probiotics) on intestinal microbial populations, have been published (Li, Zhong et al, 2015;Wang, Wu et al, 2015;Wu, Wang et al, 2012;Wu, Feng et al, 2012).…”