Intestine Of Freshwater Fishes Research Articles

Prevalence and antimicrobial susceptibility characterization of Escherichia coli isolated from the intestines of freshwater fish from the Mindu dam in Morogoro, Tanzania

Background: The Mindu dam, an open system, serves as a microbial reservoir, housing uropathogenic microorganisms like Escherichia coli. Morogoro municipality relies on the dam for water and fish. This study aimed to assess the antimicrobial susceptibility of Escherichia coli isolated from fish and water in Mindu dam. Methods: In May 2019, a cross-sectional study was conducted in Morogoro municipality. Selected antimicrobials, including ampicillin, tetracycline, cefoxitin, erythromycin, trimethoprim, gentamicin, enrofloxacin, and nalidixic acid, were tested using the disc diffusion method. E. coli ATCC 25922 served as a positive control for quality assurance during bacterial isolation. The potential source of antimicrobial contamination was identified through the multiple antibiotic resistance index. Results: Out of 148 samples, E. coli was found in 24, none in water. E. coli showed high resistance (≥50.0%) to erythromycin (62.5%), nalidixic acid (79.2%), and ampicillin (75%). Additionally, 58.0% of isolates displayed multi-drug resistance across antimicrobial classes, with a multiple antibiotic resistance index ranging from 0.00 to 0.75. Conclusion: Antimicrobial-resistant E. coli in the food chain may heighten the spread of complex urinary tract infections in the municipality. It underscores the necessity for robust municipal surveillance of antimicrobial resistance and effective antimicrobial stewardship for enhanced infection prevention and control.

Presence of Lactic Acid Bacteria in the Intestinal Tract of the Mediterranean Trout (Salmo macrostigma) in Its Natural Environment.

Knowledge of the composition of the gut microbiota in freshwater fish living in their natural habitat has taxonomic and ecological importance. Few reports have been produced on the composition of the gut microbiota and on the presence of LAB in the intestines of freshwater fish that inhabit river environments. In this study, we investigated the LAB community that was present in the gastrointestinal tract (GIT) of Mediterranean trout (Salmo macrostigma) that colonized the Biferno and Volturno rivers of the Molise region (Italy). The partial 16S rRNA gene sequences of these strains were determined for the species-level taxonomic placement. The phylogenetic analysis revealed that the isolated LABs belonged to seven genera (Carnobacterium, Enterococcus, Lactobacillus, Lactiplantibacillus, Vagococcus, Lactococcus, and Weissella). The study of the enzymatic activities showed that these LABs could contribute to the breakdown of polysaccharides, proteins, and lipids. In future studies, a greater understanding of how the LABs act against pathogens and trigger the fish immune response may provide practical means to engineer the indigenous fish microbiome and enhance disease control and fish health.

Thallium accumulation in different organisms from karst and lowland rivers of Croatia under wastewater impact

Environmental contextDespite thallium’s high toxicity, water solubility and bioaccumulation tendency, its ecotoxicological relevance is largely unknown. We investigated thallium concentrations in fish, amphipods and parasitic worms from a karst freshwater ecosystem, and estimated total and cytosolic thallium concentrations in intestine of fish from the karst and lowland rivers impacted by wastewater inflow. The study provides the first data on dietary thallium accumulation in the intestine of freshwater fishes. AbstractThe aim of the present research was to investigate the bioaccumulation of thallium (Tl), a technology-critical element, in fish intestine and muscle, gammarids and the fish intestinal parasites, acanthocephalans, and to evaluate their potential as indicators of metal exposure in aquatic environments. Moreover, total and cytosolic (metabolically available and potentially toxic fraction) Tl concentrations were measured and compared between the intestines of brown trout (Salmo trutta Linnaeus, 1758) from the karst Krka River and Prussian carp (Carassius gibelio Bloch, 1782) from the lowland Ilova River. Since there is a scarcity of information on subcellular metal partitioning in the fish intestine, the results of Tl concentrations in acid digested intestinal tissue, homogenate and cytosol represent preliminary data on Tl diet-borne uptake in salmonid and cyprinid fish. In both rivers, samplings were performed upstream (reference site) and downstream (contaminated site) of the wastewater impact in autumn and spring. Total Tl concentrations were much higher in brown trout than Prussian carp, and higher proportions of cytosolic Tl concentrations were observed in the intestinal tissue of brown trout (45–71%) compared with that of Prussian carp (32–47%). Therefore, both indicators showed species- and site-specific differences. Considering different bioindicator organisms, the most effective Tl accumulation was evident in acanthocephalans compared with the fish tissues and gammarids, which confirmed the potential of fish parasites as bioindicators of metal exposure. Trends of spatial and temporal Tl variability were mostly comparable in all indicator organisms and for total and cytosolic Tl concentrations in the intestine of salmonid and cyprinid fish species, which confirmed their application as useful biological tools in metal exposure assessment.

Genotypic characterization of Lactic acid bacteria in gut microbiome of freshwater fish

The present study focused on identification and genotypic characterization of Lactic acid bacteria (LAB) in the intestine of freshwater fish. 76 strains of LAB were isolated and identified by 16S rRNA gene sequences and hsp60 gene sequences as different strains of Lactobacillus plantarum, Lactobacillus pentosus, Lactobacillus fermentum, Lactobacillus delbrueckii subsp. bulgaricus, Lactobacillus brevis, Lactobacillus reuteri, Lactobacillus salivarius, Pediococcus pentosaceus, Pediococcus acidilactici, Weissella paramesenteroides, Weissella cibaria, Enterococcus faecium, and Enterococcus durans. The hsp60 gene showed a higher level of sequence variation among the isolates examined, with lower interspecies sequence similarity providing more resolutions at the species level than the 16S rRNA gene. Phylogenetic tree derived from hsp60 gene sequences with higher bootstrap values at the nodal branches was more consistent as compared to phylogenetic tree constructed from 16S rRNA gene sequences. Closely related species L. plantarum and L. pentosus as well as species L. delbrueckii subsp. bulgaricus and L. fermentum were segregated in different cluster in hsp60 phylogenetic tree whereas such a distribution was not apparent in 16S rRNA phylogenetic tree. In silico restriction analysis revealed a high level of polymorphism within hsp60 gene sequences. Restriction pattern with enzymes AgsI and MseI in hsp60 gene sequences allowed differentiation of all the species including closely related species L. plantarum and L. pentosus, E. faecium and E. durans. In general, hsp60 gene with higher evolutionary divergence proved to be a better phylogenetic marker for the group LAB.

Characterization and pharmacological potential of Lactobacillus sakei 1I1 isolated from fresh water fish Zacco koreanus.

BackgroundThere are still a large variety of microorganisms among aquatic animals which have not been explored for their pharmacological potential. Hence, present study was aimed to isolate and characterize a potent lactic acid bacterium from fresh water fish sample Zacco koreanus, and to confirm its pharmacological potential.MethodsIsolation of lactic acid bacteria (LAB) from fresh water fish samples was done using serial dilution method. Biochemical identification and molecular characterization of selected LAB isolate 1I1, based on its potent antimicrobial efficacy, was accomplished using API kit and 16S rRNA gene sequencing analysis. Further, 1I1 was assessed for α-glucosidase and tyrosinase inhibitory potential as well as antiviral efficacy against highly pathogenic human influenza virus H1N1 using MDCK cell line in terms of its pharmacological potential.ResultsHere, we first time report isolation as well as biochemical and molecular characterization of a lactic acid bacterium Lactobacillus sakei 1I1 isolated from the intestine of a fresh water fish Z. koreanus. As a result, L. sakei 1I1 exhibited potent antimicrobial effect in vitro, and diameter of zones of inhibition of 1I1 against the tested pathogens was found in the range of 13.32 ± 0.51 to 23.16 ± 0.32 mm. Also L. sakei 1I1 at 100 mg/ml exhibited significant (p < 0.05) α–glucosidase and tyrosinase inhibitory activities by 60.69 and 72.59 %, in terms of its anti-diabetic and anti-melanogenic potential, respectively. Moreover, L. sakei 1I1 displayed profound anti-cytopathic effect on MDCK cell line when treated with its ethanol extract (100 mg/ml), confirming its potent anti-viral efficacy against H1N1 influenza virus.ConclusionsThese findings reinforce the suggestions that L. sakei 1I1 isolated from the intestine of fresh water fish Z. koreanus might be a candidate of choice for using in pharmacological preparations as an effective drug.

Morphological and Molecular Characterization of Lactic acid Bacteria from intestine of Freshwater Fishes and Their Possible Role in Probiotic Feeding in Aquaculture

Lactic acid bacteria (LAB) are a group of gram positive, non spore forming, cocci or rod shaped, catalase negative organisms. Generally they are known as "GRAS" (Generally Recognized As Safe) organisms. In the present study, an attempt was made to isolate lactic acid bacteria from gut of two freshwa-ter fishes in Udaipur region to obtain various efficient LAB strains for indus-trial applications. A total of 12 bacterial isolates were isolated from different fishes caught from Pichola lake, Udaipur on MRS agar at 37oC. All the isolates were tested for catalase activity, colony morphology and gram staining. Further these isolates were checked for technological properties (antibacterial activity, antibiotic susceptibility and bile salt tolerance). Based on technologi-cal properties results, two isolate (F-4 &amp; F-11) have been tentatively selected for use as probiotic cultures in the aquaculture industries. They have strong antibacterial activity against various pathogens viz. Staphylococcus aureus (ATCC 9144), Micrococcus luteus (ATCC 10240), Listeria monocytogens (MTCC 1143) and have bile salt tolerance limit up to 0.7%. These are the main features for selection of probiotic candidates. To differentiate the same species molecular typing was attempted, 16S rRNA gene amplification was done using specific 16S rDNA primers and amplified gene products were di-gested with different restriction endonuclease enzymes viz EcoRI and HindIII. A total of 2 different groups out of 12 isolates were obtained. This finding reveals that isolated LAB are useful for aquaculture and also used in food preservation.

Distribution of virulence factors in ESBL-producing Escherichia coli isolated from the environment, livestock, food and humans

In this study, extended-spectrum ß-lactamase (ESBL)-producing Escherichia coli isolates recovered from the following sources were characterized with regard to the occurrence and distribution of uropathogenic and enteric pathogenic virulence factors: surface waters (rivers and lakes, n=60), the intestines of freshwater fish (n=33), fresh vegetables (n=26), retail poultry meat (n=13) and the fecal samples of livestock (n=28), healthy humans (n=34) and primary care patients (n=13). Among the 207 isolates, 82% tested positive by PCR for one or more of the virulence factors (VF) that predict uropathogenicity, TraT, fyuA, chuA, PAI, yfcv or vat. Uropathogenic E. coli (UPEC) were detected in each of the analyzed sources. Regarding virulence factors for intestinal pathogenic E. coli, these were found more rarely and predominantly associated with the aquatic environment, with aagR (EAEC) found in isolates from surface waters and STp (porcine heat stable enterotoxin) and LT (heat-labile enterotoxin) associated with isolates from fish. Aggregate VF scores (the number of unique virulence factors detected for each isolate) were lowest among isolates belonging to phylogenetic group B1 and highest among group B2. Clustering of the isolates by phylogenetic group, multilocus sequence type (MLST) and ESBL-types revealed clonal overlaps of A:ST10(CTX-M-1) and D:ST350(CTX-M-1) between the sources of livestock, poultry meat and healthy humans, suggesting livestock, in particular poultry, represents a potential reservoir for these particular UPEC clones. The clones A:ST10(CTX-M-55) and B2:ST131(CTX-M-27), harboring uropathogenic virulence factors were significantly associated with fresh vegetables and with fish, respectively. Further clonal complexes with source overlaps included D:ST38(CTX-M-14), D:ST69(CTX-M-15), D:ST405(CTX-M-15) and D:ST648(CTX-M-15), which were found in surface water and healthy humans. Identifying potential reservoirs of UPEC in the environment, animals, food and humans is important in order to assess routes of transmission and risk factors for acquiring UPEC.

Studies on pseudophyllidean cestode genus Ptychobothrium loennberg, 1889 (cestoda: ptychobothriidae, luhe, 1902) from freshwater fish Mastacembelus armatus (lacepede, 1800)

The present study deals with description of a new species of Pseudophyllidean Cestode genus Ptychobothrium, Loennberg,1889 collected from intestine of freshwater fish, Mastacembelus armatus (Lacepede, 1800) at Mahur, Dist. Nanded M.S. India during February, 2011 to January, 2013. Ptychobothrium vitellaris Sp.Nov. comes closer to all known species of genus Ptychobothrium, Loennberg, 1889 in general topography of organs but differs due to sessile Scolex, paired bothria, apical disk at anterior end of scolex, Neck absent, Mature Proglottids broader than long, Cirrus pouch pyriform, Testes 40-45 in numbers, Ovary bilobed and Vitellaria follicular.

Two Procamallanus (Spirocamallanus) species (Nematoda: Camallanidae) from freshwater fishes in the Lower Congo River

Based on light and scanning electron microscopical studies, one known and one previously undescribed Procamallanus (Spirocamallanus) species (Nematoda: Camallanidae) are described from specimens collected in the intestine of freshwater fishes in the Lower Congo River, Democratic Republic of Congo: P. (S.) daleneae (Boomker 1993) from Synodontis acanthomias Boulenger (Mochokidae, Siluriformes) (new host and geographical records) and P. (S.) parachannae sp. nov. from Parachanna insignis (Sauvage) (Channidae, Perciformes). The new species is most similar to P. (S.) serranochromis Moravec et Van As 2015, a parasite of African cichlids (Serranochromis spp.), differing from it mainly in the absence of any outgrowths on the female tail tip, a distinctly longer (546 μm) right spicule, a different length ratio of both spicules (1:2.6) and in the morphology of fourth-stage larvae. P. (S.) daleneae, a specific parasite of squeakers (Synodontis spp.), is redescribed; in contrast to the original description, the number of postanal papillae was found to be identical (6 pairs) with that of other related species.

Rhabdochona spp. (Nematoda: Rhabdochonidae) from fishes in the Central African Republic, including three new species

Based on light and scanning electron microscopical studies, three new, one already known and one not identified species of the nematode genus Rhabdochona Railliet, 1916 are reported from the intestine of freshwater fishes in Dzanga-Sangha Protected Areas (Congo River basin), the Central African Republic: Rhabdochona (Rhabdochona) centroafricana sp. n. from Barbus miolepis Boulenger, R. (R.) marcusenii sp. n. from Marcusenius greshoffii (Schilthuis), R. (Globochona) paski Baylis, 1928 from Phenacogrammus aurantiacus (Pellegrin) (new host record), R. (G.) tricuspidata sp. n. from Raiamas christvi (Boulenger) and Rhabdochona (G.) sp. (only females) from Epiplatys multifasciatus (Boulenger). Rhabdochona centroafricana is mainly characterised by the length of the left spicule (333 microm) and the presence of the operculum bearing a conspicuous gelatinous formation on one of egg poles, R. marcusenii by the length of the left spicule (453-486 microm) and the presence of a single broad filament on one egg pole only and R. tricuspidata by the body with marked cuticular ornamentations and deirids branching into three prongs. A key to valid species of Rhabdochona parasitic in fishes of Africa is provided.

Intestinal Histopathology of Trematode Infected Fish, Channa Striatus

Genarchopsis goppo, a trematode infests the intestine of fresh water fish, Channa striatus. Histopathological changes have been noticed in the intestine of fish due to infection with Genarchopsis goppo. The main objective of this study is to observe histopathological changes that occur in the intestine of fresh water fish, Channa striatus infected with the trematode, Genarchopsis goppo. Histopathological changes include shortening and destruction of villi, vacuolation of sub mucous cells, dilation of blood vessels thickening of muscles and necrosis. In the infected fish the carbohydrates, glycogen, protein and lipid contents are increased significantly. The present work deals with the histopathological changes in the intestine of infected fish. Key word s : Channa striatus, Genarchopsis goppo, Histopathology

Two new species of Rhabdochona (Nematoda: Rhabdochonidae) from freshwater fishes in Thailand

Two new species ofrhabdochonid nematodes are described from the intestine of freshwater fishes in Chiang Mai Province, northern Thailand: Rhabdochona (Rhabdochona) pseudomysti sp. n. from the catfish Pseudomystus siamensis (Regan) (Bagridae, Siluriformes) in the Fang Brook, a tributary of the Kok River (the Mekong River basin), Fang District and Rhabdochona (Globochona) thaiensis sp. n. from the cyprinid Mystacoleucus marginatus (Valenciennes) (Cyprinidae, Cypriniformes) in the Ping River (the Chao Phraya River basin), Muang District. Rhabdochona pseudomysti is mainly characterized by simple, leaf-like oval deirids (a unique feature among Rhabdochona spp.), a prostom with 14 anterior teeth, the presence of basal prostomal teeth, the length ratio of the muscular and glandular portions of oesophagus (1:2.1-2.6), an unusually long left spicule (1.10-1.22 mm), length ratio of spicules (1:11.5-14.7), arrangement of genital papillae, and conspicuously elevated vulval lips. Rhabdochona thaiensis differs from other representatives of the subgenus Globochona Moravec, 1972 possessing caudal projections on the tail tip in that it has only 2 claw-shaped projections located ventrally on the tail tip of both males and females; the species is mainly characterized by the presence of distinct pseudolabia, 8 anterior prostomal teeth, absence of basal teeth, bifurcated deirids, length ratio of the muscular and glandular portions of oesophagus (1:11.3-11.9), conspicuously short (135-141 microm) left spicule, arrangement of genital papillae, and somewhat elevated vulval lips. Fully developed eggs of R. pseudomysti and R. thaiensis remain unknown. These are the first nominal species of Rhabdochona reported from Thailand.

Observations on two nematode species parasitizing freshwater fishes in Thailand, including Spinitectus thaiensis sp. nov. (Cystidicolidae) from Pseudomystus siamensis (Bagridae)

AbstractOne new and one already known species of parasitic nematodes are described from the intestine of freshwater fishes in Chiang Mai Province, northern Thailand: Spinitectus thaiensis sp. nov. (Cystidicolidae) from the catfish Pseudomystus siamensis (Regan) (Bagridae, Siluriformes) in the Fang Brook, a tributary of the Kok River (the Mekong River basin), Fang District and Oceanicucullanus chitwoodae Le-Van-Hoa et Pham-Ngoc-Khue, 1971 (Cucullanidae) from the cyprinid Mystacoleucus marginatus (Valenciennes) (Cyprinidae, Cypriniformes) in the Ping River (the Chao Phraya River basin), Muang District. The new species, S. thaiensis, is very similar to S. petrowi Belous, 1965, differing from it, in addition to some biometrical differences, mainly in having simple cuticular spines (instead of transversely oriented peg-like spines with rounded ends) on the ventral surface of the female tail; the spicules are 156–171 and 66–72 μm long, the vulva is situated at 74% of female body length, and the entire oesophagus including the vestibule represents 14–15% of body length in the male and 12% in the female. The latter species, O. chitwoodae, was studied for the first time by scanning electron microscopy, which enabled to recognize some previously unrecorded morphological details in this species. The finding of O. chitwoodae in M. marginatus in Thailand represents new host and geographical records for this nematode.

Pseudomonas chlororaphis subsp. piscium subsp. nov., isolated from freshwater fish

Gram-negative, aerobic, motile, rod-shaped bacteria were isolated from the intestines of freshwater fish on two separate occasions. Colonies of both strains, JF3835(T) and JF4413, produced non-diffusible green pigment following 4-5 days incubation on Luria-Bertani agar. The most abundant fatty acids were summed feature 3 (comprising C(16 : 1)ω7c and/or C(15 : 0) iso 2-OH), C(16 : 0) and C(18 : 1)ω7c. The DNA G+C content was 62.9 mol%. Sequence analysis of the 16S rRNA gene indicated 100 % sequence similarity between the two strains. In comparison with recognized species, the new strains exhibited the greatest degree of sequence similarity with members of the Pseudomonas chlororaphis subspecies: P. chlororaphis subsp. chlororaphis (99.84 %), P. chlororaphis subsp. aurantiaca (99.75 %) and P. chlororaphis subsp. aureofaciens (99.40 %). While DNA-DNA relatedness confirmed the placement of strains JF3835(T) and JF4413 as members of the species P. chlororaphis, multilocus sequencing indicated that the strains formed a distinct cluster within it. On the basis of genotypic and phenotypic evidence, strains JF3835(T) and JF4413 represent a novel subspecies of the species P. chlororaphis, for which the name Pseudomonas chlororaphis subsp. piscium subsp. nov. is proposed. The type strain is JF3835(T) (=NCIMB 14478(T)=DSM 21509(T)).

Seasonal and tissue distribution of Laribacter hongkongensis, a novel bacterium associated with gastroenteritis, in retail freshwater fish in Hong Kong

Laribacter hongkongensis, a recently discovered bacterium associated with community-acquired gastroenteritis, has been found in the intestines of freshwater fish. To better understand the epidemiology and ecology of the bacterium, we carried out a surveillance study to investigate possible seasonal variation in the recovery of L. hongkongensis and its distribution in various organs in retail freshwater fish in Hong Kong. Forty whole freshwater fish of two species (20 grass carps and 20 bighead carps), and intestines from 120 grass carps were sampled during a one-year period. L. hongkongensis was isolated from 11 (55%) of the 20 grass carps and 6 (30%) of the 20 bighead carps; and the intestines of 49 (41%) of 120 grass carps. Seasonal variation in the recovery of L. hongkongensis from both whole fish and intestines was observed, with higher isolation rates in spring and summer than in fall and winter. There was also positive correlation between temperature and the isolation rates. When L. hongkongensis was cultured in vitro at different temperatures, shorter lag time and higher growth rate were observed at higher temperatures, with 37 °C being optimal among the tested temperatures. L. hongkongensis was commonly found in the gills, stomachs and intestines in both grass carps and bighead carps, and on the skin surface of one fish, but not in other organs. Proper handling of freshwater fish for cooking, especially the gills and gut, is recommended to prevent acquisition of L. hongkongensis, and other freshwater fish related infections.

Screening of Lactobacilli from Fish Intestines to Select a Probiotic for Warm Freshwater Fish

The aim of this study was to select a Lactobacillus with probiotic abilities suitable for in vivo studies in farmed freshwater fish. Fifty-five Lactobacillus isolated from the intestines of freshwater fish were screened for inhibition of fish and human pathogenic bacteria in vitro; and some selected strains by absence of production of biogenic amines and resistance to gastric and intestinal fluids (GIF) in a simulation model. A strain was studied in co-cultures with a pathogen in fish feed extract. Selected strains were tentatively identified as Lactobacillus plantarum 44a, whose a mechanism of inhibition was based on acid production, and L. brevis 18f which was detected as a high H 2 O 2 producer, because its supernatant adjusted to pH 6 strongly inhibited Aeromonas hydrophila; this activity was not observed when supernatant was treated with catalase. In the exposure of cells to GIF, L. plantarum 44a survived better than the other strains to pH 2, 2.5 and 3 and pepsin. L. brevis 18f had a very low survival in GIF. L. plantarum 44a co-cultured with A. hydrophila in fish feed extract with an initial ratio 10 3 : 10 7 and 10 7 : 10 3 respectively, started killing the pathogen when pH was around 5.5. L. plantarum 44a has potential applications as probiotic in freshwater fish. L. brevis 18f as a H 2 O 2 producer may have application as a possible fish pathogen antagonist in the upper gastrointestinal tract, the skin, the gills and eggs where oxygen is available.

Observations on the life history ofDeretrema minutumManter, 1954 (Digenea: Zoogonidae) in freshwater crustacean and fish hosts from Canterbury, New Zealand

Abstract Two new hosts are recorded for Deretrema minutum Manter, 1954 from freshwater habitats at Lake Ellesmere, Canterbury. These are the mysid Tenagotnysis chiltoni Tattersall, 1923 which acts as a second intermediate host and harbours the encysted metacercariae, and the smelt, Retropinna retropinna (Richardson, 1848), which contains adult worms. Adult D. minutum were also found in the inanga Galaxias maculatus Jenyns, 1842. A large proportion of metacercariae within the crustacean host exhibited progenesis which results in the production of numerous eggs. Ovigerous metacercariae were identical with adult D. minutum recovered from the intestine of freshwater fishes from Lake Ellesmere. A description of the metacercaria is given.

Microflora in the gastrointestinal tracts of freshwater fish - II. Characteristics of obligate anaerobic bacteria in the intestines of freshwater fish.

One hundred and nine srains of obligate anaerobic bacteria isolated from the intestines of 6freshwater fish were examined for morphological, physiological and biochemical characteristics. They were divided into two distinct groups, A and B, which consisted of two single species, judging from the consistency of most characteristics within each group. They were non-motile, non-sporing, gram-negative, obligate anaerobic rods which produced acetic acid but not butyric or lactic acid as major products in PYFG broth. Based on these rsults, both groups should belong to the genus Bacteroides. Most of the obligate anaerobic strains demonstrated no activity or weak activity in macromolecule hydrolysis and carbohydrate fermentation compared with facultative anaerobes isolated from fish intestines.

Microflora in the gastrointestinal tracts of freshwater fish - I. Isolation and distribution of obligate anaerobic bacteria from the intestines of freshwater fish.

Enumeration and isolation of obligate anaerobes from the intestines of freshwater fish were undertaken using various media and anaerobic culture methods. NBGT modified (NBGT-1/3S) was found to be the most useful medium in selection of obligate anaerobes from freshwater fish. Obligate anaerobes were commonly present in the intestines of various freshwater fish and showed a range of viable counts on NBGT-1/3S agar from 106 to 109 per gram of intestinal contents. Obligate anaerobes were predominant over facultative anaerobes especially in the intestines of Tilapia fish and ayu among the fish samples tested. Using EG and NBGT-1/3S agar, two types of bacteria which belong to the family Bacteroidaceae were isolated from various freshwater fish.

REMARKS ON THE DIPLOMASTIGINE FLAGELLATES FROM THE INTESTINE OF FISHES.

In the intestine of freshwater fishes, two morphologically different types of diplomastigine flagellates have so far been found to exist: Hexamita salmonis (Moore, 1920) specific for fishes, and Spironucleus elegans Lavier, 1936, identical with the flagellate from amphibia.The identity of the Spironucleus from fishes and amphibia has been demonstrated by infecting Pterophyllum scalare with flagellates from newts per os, per rectum and with contaminated food.A redescription of motile stages of both Hexamita salmonis and Spironucleus elegans is presented, together with a list of existing findings of fish diplomastigines, and a brief discussion.