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1

Characterization and identification of gut-associated phytase-producing bacteria in some fresh water fish cultured in ponds

100%
Khan A., Ghosh K.
Acta Ichthyologica et Piscatoria
|
2012
|
tom 42
|
nr 1
Background. Phytase produced by gut bacteria increases the availability of phosphorus and other important nutrients in ruminants by virtue of enzymatic hydrolysis of the phytic acid, an antinutritional factor present in the majority of plant feedstuffs. This topic, however, has been insufficiently investigated in fish. This study was intended: to evaluate the presence of phytase-producing autochthonous bacteria in the gastrointestinal (GI) tracts of 14 freshwater teleost fishes; and to identify the most promising phytase-producing strains by phenotypic characterization and 16S rDNA. Materials and Methods. The GI tracts were removed and divided into proximal (PI) and distal (DI) intestine. Homogenates of intestinal segments were spread onto sterilized tryptone soya agar and modified phytase screening media (MPSM) plates to determine autochthonous culturable heterotrophic and phytase-producing microbiota, respectively. Data were presented as log viable counts (LVC) g-1 intestine. Out of 95 phytase-producing isolates, primarily selected 32 isolates were studied for phytase-assay using MPSM broth. Promising phytase-producing isolates were evaluated for other exo-enzymes (amylase, cellulase, protease, lipase) using 4 selective media. Two most promising phytase-producing isolates were identified by phenotypic characterization and 16S rDNA. Results. Population of heterotrophic bacteria was highest (LVC = 8.29 g-1 intestine) in the DI of Gudusia chapra followed by DI of Hypophthalmichthys molitrix (LVC = 6.82 g-1 intestine). However, more than log 4 reduction of the phytase-producing bacteria was observed compared to heterotrophic bacteria. Phytase-producing microbiota was highest in the PI of G. chapra (LVC = 3.95 g-1 intestine) followed by PI of Labeo calbasu (LVC = 3.78 g-1 intestine). The strain LB1.4 isolated from DI of Labeo bata showed highest phytase activity (2.33 ± 0.006 U · mL–1) followed by the strain GC1.2 (2.19 ± 0.018 U · mL–1) isolated from PI of G. chapra. Both isolates were efficient in producing other exo-enzymes. Phenotypic characterization and nucleotide homology analysis revealed that the isolates LB1.4 and GC1.2 were similar to Bacillus subtilis and Bacillus atrophaeus, respectively. Conclusion. Autochthonous phytate degrading bacteria were present in the GI tract of fish that might endow ecological advantages to overcome the anti-nutritional effects of plant phytate.
2

Gastrointestinal bacteria in rohu, Labeo rohita (Actinopterygii: Cypriniformes: Cyprinidae): scanning electron microscopy and bacteriological study

81%
Ghosh K., Roy M., Kar N., Ringo E.
Acta Ichthyologica et Piscatoria
|
2010
|
tom 40
|
nr 2
Background. Fish gut bacteria may be used as probiotics for fish. Those occurring in the gastrointestinal (GI) tract of rohu, Labeo rohita (Hamilton, 1822), have not been sufficiently studied. This study was intended: to detect bacteria in the intestine of rohu by scanning electron microscopy (SEM); to evaluate the existence of heterotrophic, proteolytic, amylolytic, and cellulolytic bacteria in three different regions of the gut of rohu; and to identify more than 25% of the isolated gut bacteria by 16S rRNA. Materials and Methods. The GI tracts were removed and divided into three regions: foregut, midgut, and hindgut. Tissues used for SEM were fixed in glutaraldehyde, washed in heparinised saline, dehydrated in graded ethanol, fixed in amyl acetate, dried with liquid nitrogen, coated with gold, observed, and photographed. Homogenates of the intestinal segments were spread onto tryptic soy agar plates and selected nutrient media plates to determine heterotrophic, proteolytic, amylolytic, and cellulolytic bacterial populations, respectively. Of the 59 adherent bacterial strains isolated from the GI tract of rohu 16 isolates were tried for identification by 16S rRNA genes. Results. Bacteria were observed to adhere to the gut enterocyte surfaces. Population level of enzyme-producing bacteria was higher in the midgut and hindgut regions than that observed in the foregut region. Furthermore, dense amylolytic and cellulolytic bacterial population in comparison to the proteolytic population was noticed in the GI tract of L. rohita. Highest density of the cellulolytic bacterial population in the hindgut region may indicate that fermentative degradation occurs in this part of the GI tract. Eleven adherent bacterial strains belonged to bacilli, 2 strains to Pseudomonas, 1 strain to Aeromonas, 1 strain was most closely related to Enterobacter, while 1 strain showed < 97% 16S rRNA sequence similarity in BLAST program was treated as unknown. Conclusion. Autochthonous bacteria were present in the GI tract of rohu and that the autochthonous microbiota possess enzymatic activity that might be beneficial for the fish.
3

Potential gut adherent probiotic bacteria isolated from rohu, Labeo rohita (Actinopterygii: Cypriniformes: Cyprinidae): Characterisation, exoenzyme production, pathogen inhibition, cell surface hydrophobicity, and bio-film formation

81%
Dutta D., Banerjee S., Mukherjee A., Ghosh K.
Acta Ichthyologica et Piscatoria
|
2018
|
tom 48
|
nr 3
4

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

81%
Talukdar S., Ringo E., Ghosh K.
Acta Ichthyologica et Piscatoria
|
2016
|
tom 46
|
nr 3
5

Growth and survival of rohu, Labeo rohita [Hamilton, 1822] spawn fed diets fermented with intestinal bacterium, Bacillus circulans

80%
Ghosh K., Sen S. K., Ray A. K.
Acta Ichthyologica et Piscatoria
|
2004
|
tom 34
|
nr 2
Background. Because of the advancement of multiple spawning of carps, the importance of a quality larval diet is increasing day by day. The larval fish do not have the necessary enzyme or the amount of digestive enzymes to digest feed at optimum level. Therefore, fermentation of feed ingredients and/or formulated diets by bacterial enzymes to produce simpler forms of nutrients may be beneficial for them. Materials and Methods. Five isocaloric (4.38 kcalּg-1) and isonitrogenous (35% crude protein approximately) experimental diets (D1-D5) containing 32% fish meal, 34% mustard oil cake, 30% rice bran, and 2% cod liver oil, were fermented in vitro with Bacillus circulans cells (at the rate of 108 bacterial cells per g) at 37oC for 1-5 day duration (1 day: D1, 2 days: D2, 3 days: D3, 4 days: D4, and 5 days: D5). The bacterial strain [extracellular enzyme producer Bacillus circulans (Lr 1.1)] used for fermentation was isolated from the intestine of rohu, Labeo rohita fingerlings. The reference diet (RD), containing same ingredients, was not fermented with bacterial cells. Rohu spawn (av. wt. 0.35 Âą 0.01 mg) were fed ad libitum for 21 days in the laboratory condition at 30 minutes interval starting from 0900 h to 1600 h. Results. Fermentation of diets resulted in an increase in crude protein and free amino acid contents and decrease in crude fibre content. Diets D4 and D5 resulted in best growth and survival (98% and 98.33%, respectively) of rohu spawn compared to those fed with the reference diet (RD) and other experimental groups. A significant positive correlation was obtained between RNA : DNA ratio and specific growth rate (SGR) of 18 dietary groups (6 groups in triplicate). Conclusion. Fermentation of feed ingredients may be practiced as a tool for starter diet formulation to obtain better growth and survival of rohu spawn. The enzyme-producing strain, Bacillus circulans could be used to ferment diets for 4 to 5 days to increase the bioavailability of nutrients.
6

Growth and survival of rohu, Labeo rohita [Hamilton] spawn fed diets supplemented with fish intestinal microflora

80%
Ghosh K., Sen S. K., Ray A. K.
Acta Ichthyologica et Piscatoria
|
2002
|
tom 32
|
nr 1
A 21-day feeding experiment was conducted to assess the effects of diets supplemented with fish intestinal bacteria producing extracellular enzyme on growth and survival of rohu, Labeo rohita (Hamilton) spawn (average weight 0.3 mg). Intestinal bacteria were isolated from healthy rohu fingerlings (average weight 3.51 ±0.31 g). Six isocaloric (4.24 kcalּg-1) and isonitrogenous (approximately 35% crude protein) diets (D1-D6) were prepared containing 32% fish meal, 34% mustard oil cake, 30% rice bran, 2% cod liver oil, and 2% vitamin premix. Experimental diets (D2-D6) were supplemented with the isolated bacterial strain Bacillus circulans Lr 1.1 at five different levels (4 × 105, 4 × 106, 4 × 107, 4 × 108 and 4 × 1010 cells per 100 g of feed, respectively). Rearing of spawn on diet D5 (supplemented with 4 × 108 cells per 100 g) resulted in better growth and survival (97.33 ±1.15%) of rohu spawn compared to those with the control diet (diet D1, without any microflora supplementation) and other experimental diets. Diet D5 resulted in significantly higher growth and specific growth rate (SGR) followed by diets D6 and D4. RNA and DNA contents in the spawn were measured as an index of growth. The correlation coefficient (r value) of 0.831 and regression line having a slope of 0.79 suggested a significant positive correlation (0.01 level) between RNA-DNA ratio and specific growth rate.
7

Feed utilization efficiency and growth performance in rohu, Labeo rohita [Hamilton, 1822], fingerlings fed yeast extract powder supplemented diets

80%
Ghosh K., Sen S. K., Ray A. K.
Acta Ichthyologica et Piscatoria
|
2005
|
tom 35
|
nr 2
Background. Yeast extract powder (YEP) is a rich source of several B vitamins and is used mainly in bacterial culture. In the present study, the effect of dietary supplementation of YEP on growth, feed conversion, nutrient ADC, body composition, and digestive enzyme profile of rohu, Labeo rohita (Hamilton, 1822) fingerlings was evaluated. Materials and Methods. Rohu fingerlings (mean individual weight 1.76 ± 0.15 g) were fed, twice daily, fish meal-based 35% protein diets supplemented with YEP (0.1%, 0.2%, 0.3%, 0.4%, and 0.5% on dry matter basis) for 75 days at 3% of body weight, in triplicate. Fish performance in terms of growth, apparent nutrient digestibility, and whole body composition was studied. The intestinal protease and amylase activities were also determined in rohu fingerlings fed YEP-supplemented diets. Microbial cultures of the intestinal mucosa of the fish in all dietary treatments were carried out after the feeding trial in soybean-casein digest agar (TSA), gelatin-peptone (GP), starch (ST) and carboxymethylcellulose (CMC) plates, separately, to determine the protease- amylase-, and cellulase-producing capacities (qualitative) of the isolated organisms. Results. The fish fed YEP-supplemented diets exhibited better growth than the control up to 0.2% level. YEP at 0.1% level resulted in the best performance of the fish in terms of per cent weight gain, SGR, FCR, and PER, followed by the 0.2% level. YEP led to higher deposition of protein and lower deposition of lipid in the carcass. The intestinal protease activity was highest in the fish fed 0.1% yeast, followed by 0.2%. Protease-producing capacity of the intestinal bacterial flora in the in vitro cultures followed the same trend. Conclusion. It appears therefore that YEP in the diets might have some effect on the gut microflora by supplying additional digestive enzymes leading to better nutrient utilization.
8

Isopora ceylonensis sp.n. from a grey- headed fly catcher, Culicicapa ceylonesis calochrysea Oberholser

71%
Sinha C. K., Sinha S., Chattoraj N., Bandyopadhyay S., Ghosh K.
Acta Protozoologica
|
1978
|
tom 17
|
nr 4
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