Antimicrobial ability and growth promoting effects of feed supplemented with probiotic bacterium isolated from gut microflora of Cirrhinus mrigala

Abstract

The present studies were conducted to isolate, select, identify and characterize gut bacteria as antimicrobial and growth promoting agent for the feed of economically important fish Cirrhinusmrigala. Intestinal microflora were isolated, counted, and identified, and their in vitro antibacterial properties were determined. The results have revealed that occurrence of gram negative rods was around 75% and of gram positive rods was 25%. Amongst the isolates gram positive were maintained in nutrient agar slants at 4°C. Of these, eight strains were replica-plated on agar seeded with Aeromonashydrophila and only one strain CM2 (Cirrhinus mrigala 2) exhibited antibacterial properties in vitro showing inhibition against fish pathogen by well diffusion assay. This isolated strain was identified as Bacillus cereus. This bacterium was mass cultured and incorporated in the pelleted diet (40% protein and 18 kJ g-1 gross energy) of C. mrigala to investigate its effect on growth performance, digestibility, nutrient retention and activities of digestive enzymes. The results of feeding trial revealed significantly (P<0.05) high growth performance in terms of specific growth rate, growth percent gain in body weight (272.4±1.5), high apparent protein digestibility ((79.9±0.30)%) and low food conversion ratioin the group of fishes fed on diet containing B. cereus in comparison to the fishes fed on diet without probiotics. The carcass composition also revealed high accumulation of proteins ((15.28±0.15) g 100 g-1) in fishes fed on diet containing probiotics. Intestinal enzyme activities of protease, amylase and cellulase were also significantly (P<0.05) high in the group of fishes fed on diet supplemented with probiotic indicating the extracellular enzyme production by B. cereus. These results indicate that probiotic stimulate the digestion through the supply of digestive enzyme and certain essential nutrients to animals. Also significantly (P<0.05) low excretion of metabolites, i.e., ammonia excretion and phosphate production (mg kg-1 BW d-1) was observed in the fishes fed with probiotic based diets. Thus, B. cereus appears to be a promising candidate for ptobiotic applications which can enhance growth performance and nutrient retention in C. mrigala.

Molecular Characterization and Dosage Application of Autochthonous Potential Probiotic Bacteria in Cirrhinus mrigala

“…The probiotic property of antagonism was confirmed by the results demonstrating the inhibitory effect against Aeromonas hydrophila. Here we observed a strong antibacterial activity of B. cereus strain SL1 showing the maximum inhibition (20 mm in diameter) against the pathogenic strain Aeromonas hydrophila, when performed by well diffusion assay which are not seen for wild-type strains (Bhatnagar and Lamba, 2015).…”

“…The phylogenetic tree was plotted using Phylp 3.69 software and tree (phylogram) visualization was done by TreeViewX (Figure 2). Partial 16S rDNA gene sequence data analysis of strain CM2 showed high arrangements between traditional and molecular identification as established by traditional characterization earlier (Bhatnagar and Lamba, 2015), and the isolate was finally identified as Bacillus cereus strain SL1. However, distinguishing between toxic wild-type Bacillus cereus strains and this probiotic strain is crucial to assess the quality and possible hazard of feed.…”

Paddy cum fish culture: Growth performance of Channa punctatus, paddy yield and economics

“…The results of present study revealed that survival rates of fish were high in all the treatments between 73-90% for C. punctatus. Sarkar et al (2005) Bhatnagar and Lamba (2015) have also reported carcass protein in this range where experimental fish were fed on growth promoting diets clearly supporting that flesh quality of fish from rice cum fish culture has same nutritive value as in other intensive nutrition tests. The present study is also in accordance to the enhanced growth performance of C. carpio in paddy fields .…”

Unveiling the Impact of the Enigmatic Probacterium (Bacillus) on Aquatic Life: A Comprehensive Exploration into its Effects on Fish and Shellfish

“…B.fusiformis also administered to L. vannamei daily or at intervals increased survival and prevented disease as immune system was boosted. [212]. On the other hand, B. subtilis increased Litopenaeus vannamei's antioxidant capacity and phenoloxidase activities [213].…”