Isolation and characterization of new potential probiotic bacteria based on quorum-sensing system

Aims: This work was aimed at identifying strains which can degrade quorum‐sensing (QS) molecules from fish gut, with properties suitable for use as probiotic in aquaculture. Methods and Results: A total of 200 strains were obtained from the intestine gut of Carassius auratus gibelio after enrichment in KG medium contained 500 μg l^?1 of C6‐HSL as the sole source of carbon and nitrogen; one strain named QS inhibitor (QSI)‐1 was identified as the genus Bacillus spp. by morphological phenotypes, and the strain also possessed an aiiA homologue gene using PCR amplification. In vitro, QSI‐1 strongly interfered with violacein production by Chromobacterium violaceum. Coculture of QSI‐1 with fish pathogen effectively reduced the amount of acyl‐homoserine lactones (AHLs) and the extracellular proteases activity of Aeromonas hydrophila YJ‐1. The oral LD50 of QSI‐1 to fish was more than 10¹¹ CFU shown that it was avirulent to fish. Fish fed diet supplemented with QSI‐1 had good survival, suggesting that QSI‐1 showed protection against Aer. hydrophila infection. Conclusions: The results indicate that the isolate QSI‐1 might have the potential possibility to be used as a probiotic in aquaculture. Significance and Impact of the Study: This is the first report to describe a bacterium isolated from the intestine gut of C. auratus gibelio which can degrade AHLs and has the probiotic characteristics for its use in aquaculture.     

Development of paratransgenic Artemia as a platform for control of infectious diseases in shrimp mariculture

Aim: To study the accumulation and retention of recombinant proteins in Artemia gut for optimizing paratransgenic disease control in shrimp aquaculture. Methods and Results: Transgenic Escherichia coli expressing fluorescent marker proteins and the transgenic cyanobacterium Synechococcus bacillarus expressing a functional murine single chain antibody, DB3, were fed to Artemia franciscana. Stable expression and retention of several marker molecules (e.g. GFP, DS Red and DB3) up to 10 h after of feeding with E. coli were evident within the gut of Artemia. Engineered strains of S. bacillarus expressing DB3 accumulated within the gut of Artemia with detectable antibody activity for 8–10 h of feeding via ELISA, coincident with the time period of the highest density of transgenic S. bacillarus in the Artemia gut. Conclusions: Artemia fed transgenic bacteria or algae accumulated recombinant proteins for up to 10 h that retained biological activity. Co‐delivery of multiple recombinant proteins simultaneously in the gut of Artemia was also demonstrated. Significance and Impact of the Study: Expression of molecules that target infectious agents of mariculture in shrimp via commonly deployed feed organisms such as Artemia could potentially offer powerful new tools in the ongoing global effort to increase food supply.     

Further evidence and characterization of Artemia franciscana (Kellogg, 1906) populations in Argentina

Aim This paper reports the presence of Artemia franciscana ( Kellogg, 1906 ) in Mar Chiquita (CHI) salt lake and in Las Tunas (TUN) lagoon, as well as at a shallow lake in Salinas Grandes (Province of Córdoba) in Argentina. To date, this species has been considered absent from Argentina. This study also provides further data on the characterization of the A. franciscana populations from this area. Location Province of Córdoba (Argentina). Methods The cyst samples collected at the three hypersaline environments were measured to assess its mean diameter with a dissecting microscope. The length of the nauplii hatched from the cysts was also determined with the microscope. The adults raised from these nauplii under strictly controlled conditions were analysed for 12 morphological parameters and compared through multivariate discriminant analysis with other American populations. Fatty acids from the total lipids were analysed by gas chromatography. Reproductive compatibility was evaluated from single‐pair intraspecific and interspecific crosses of adult specimens. Results The results endorse the morphometric assimilation of the Artemia populations of this area to other American populations of the A. franciscana‘super‐species’, together with its morphometric differentiation from the species A. persimilis ( Piccinelli & Prosdocimi, 1968 ). The more conspicuous population from CHI shows cross‐fertility with A. franciscana original from San Francisco Bay (California, USA). Both populations from CHI and TUN show cross‐fertility between them and reproductive isolation with A. persimilis from Hidalgo (Province of La Pampa), which to date is considered to be endemic or exclusive of hypersaline ecosystems in Argentina. The reproductive characteristics displayed by the population from TUN lagoon suggest the existence of an occasional hybridization between A. franciscana and A. persimilis ( Papeschi et al., 2000 ). Artemia cysts from CHI and TUN show a fatty acid profile rich in eicosapentaenoic acid differing markedly from the fatty acid profiles found in A. persimilis cysts. Main conclusions: Artemia franciscana is present in Argentina at 36° S and north of this latitude. Artemia persimilis is confined to the south of latitude 37°10′ S. There are different pieces of evidence that point to a certain level of hybridization of the two species taking place in the land belt between these parallels.     

A small IncQ-type plasmid carrying the quinolone resistance (qnrS2) gene from Aeromonas hydrophila

Aims: To investigate the qnrS2 gene encoded by a plasmid obtained from Aeromonas hydrophila. Methods and Results: To investigate the full‐length sequence of the plasmid carrying qnrS2 (plasmid designated pAHH04) from the strain SNUFPC‐A10, the full‐length coding sequence of the qnrS region was first amplified. The remaining part of the plasmid was read outwards from this region. The plasmid pAHH04 contained the repC, repA, mobA and mobC genes, and its total size was 7191 bp with a G+C content of 60%. Conclusions: This study describes the full‐length sequence of a plasmid carrying the qnrS2 gene from Aer. hydrophila. The plasmid pAHH04 carried plasmid replication and mobilization genes from IncQ‐type plasmids. Significance and Impact of the Study: The isolated qnrS2 gene encoded by a plasmid from an Aer. hydrophila strain is of significant importance because it emphasizes the problem of antibiotic resistance as well as the ability of the determinants to spread among the different bacterial species that impact human health.     

Role of the probiotic strain Lactobacillus paracasei LMGP22043 carried by artichokes in influencing faecal bacteria and biochemical parameters in human subjects

Aims: To evaluate the positive influence of the probiotic strain Lactobacillus paracasei LMGP22043 carried by artichokes into the human gut with special reference to faecal bacterial balance, short‐chain fatty acid concentrations and enzyme activities in a randomized, double‐blind human trial in comparison with probiotic‐free artichokes (control). Methods: Twenty subjects were randomized into two groups, which consumed daily 180 g of the artichoke product (probiotic or control) during two 15‐day study periods (periods 1 and 2) separated by a 15‐day washout in a crossover manner. Faecal samples were subjected to microbiological and biochemical analyses, and a strain‐specific PCR was performed to monitor the probiotic strain. Results: The probiotic strain, transported by the vegetable matrix, transiently colonized the gut of 17/20 subjects (median 6·87 log CFU g^?1 faeces), antagonized Escherichia coli and Clostridium spp. and increased the genetic diversity of lactic population based on REP‐PCR profiles, mainly after period 1. Conclusions: The probiotic L. paracasei LMGP22043 successfully colonized the human gut and positively influenced faecal bacteria and biochemical parameters. Significance and Impact of the Study: The association of the probiotic L. paracasei with a food carrier rich in fibre can represent a new strategy for favouring a daily supply of probiotics and attracting more consumers to vegetable food fortified with probiotic strains.     

An in vitro screening method to evaluate chemicals as potential chemotherapeutants to control Aeromonas hydrophila infection in channel catfish

Aims: To develop an in vitro screening method to be used for identifying potential effective chemotherapeutants to control Aeromonas hydrophila infections. Methods and Results: Using catfish gill cells G1B and four chemicals (hydrogen peroxide, sodium chloride, potassium permanganate and d ‐mannose), the feasibility of using an in vitro screening method to identify potential effective chemotherapeutants was evaluated in this study. In vitro screening results revealed that, at concentration of 100 mg l^?1, H₂O₂ was the only chemical tested that was able to completely abolish the attachment and invasion of Aer. hydrophila to catfish gill cells. In vivo virulence studies using live channel catfish through bath immersion confirmed that H₂O₂ was the only chemical tested that was able to significantly (P < 0·001) reduce the mortality (from 90 or 100% to 0 or 20%) caused by Aer. hydrophila infections. Conclusions: The in vitro screening method using catfish gill cells G1B could be used to initially identify potential effective chemotherapeutants to control Aer. hydrophila. Significance and Impact of the Study: An in vitro screening method using catfish gill cells to identify potential effective chemotherapeutants described here will cut cost in research compared with the method of using live fish to screen lead compounds for fish disease control.     

Comparing the potential for dispersal via waterbirds of a native and an invasive brine shrimp

1. Migratory waterbirds are likely to have a major role in the spread of many exotic aquatic invertebrates by passive dispersal. However, in the field, this has so far only been confirmed in the case of the American brine shrimp Artemia franciscana, which is spreading quickly around the Mediterranean region. 2. We compared experimentally the capacity of A. franciscana and the native brine shrimp Artemia parthenogenetica to disperse via migratory shorebirds. After Artemia resting eggs (cysts) were fed to Redshank Tringa totanus and Dunlin Calidris alpina, we compared the proportion that survived gut passage, their hatchability and their retention time within the gut. We also tested the ability of cysts to stick to the feathers of Black‐tailed Godwit Limosa limosa. 3. The proportion of ingested cysts retrieved from faeces was the same for each Artemia species (8%), and there were no significant differences in retention time (mean 1.2 h and maximum 10 h for A. parthenogenetica, 1.4 and 12 h for A. franciscana) or hatchability (11% versus 14%). The two shorebird species showed similar retention times and retrieval rates, but cysts recovered from Dunlin had a significantly higher hatchability. Only one of the 1000 A. parthenogenetica cysts and three of the 1000 A. franciscana cysts stuck to feathers. 4. These results indicate that both non‐native and native brine shrimps have a similar high capacity for endozoochory via birds, and that the invasiveness of A. franciscana is probably explained by its competitive superiority owing to high fecundity and release from cestode parasitism. Owing to their different migratory behaviour, Redshank and Dunlin are likely to have different roles as brine shrimp vectors. Brine shrimps provide a suitable model for understanding the role of birds in the dispersal of exotic aquatic invertebrates.     

In vitro evaluation on adherence and antimicrobial properties of a candidate probiotic Clostridium butyricum CB2 for farmed fish

Aims: To characterize the antimicrobial and adhesion ability of candidate probiotic Clostridium butyricum CB2 for farmed fish in vitro. Methods and Results: The potential probiotic Cl. butyricum CB2 had been evaluated for its adhesion capacity and antagonistic effect against two fish pathogens Aeromonas hydrophila and Vibrio anguillarum by the intestinal cell model. In addition, the aggregation ability and antimicrobial property on agar plate were assayed. The results indicated that the candidate probiotic Cl. butyricum CB2 have strong adhesion property and a higher antagonistic activity to Aer. hydrophila and V. anguillarum both on agar plate and cell model. Clostridium butyricum showed a higher aggregation which might be the reasons for bacteria adhesion and antimicrobial activity. Conclusions: The strain Cl. butyricum CB2 could be used as potential probiotic to inhibit pathogens growth and prevent their colonization in fish intestinal tract. Significance and Impact of the Study: This study revealed the antimicrobial and adhesion characteristic of Cl. butyricum CB2 which was selected as the potential probiotic to farmed fish.     

Larval rearing of burbot (Lota lota L.) using Brachionus calyciflorus rotifer as starter food

Burbot Lota lota L. is one of the endangered freshwater fish species in western Europe for which the development of controlled larval rearing procedures could produce enough material for stock enhancement. The suitability of the freshwater rotifer Brachionus calyciflorus as a start food for larviculture of burbot was investigated. After yolk‐absorption, the larvae were stocked in 40‐L tanks under different feeding conditions: clear water rearing conditions with rotifers (Brachionus calyciflorus) for 10 days (R), green water conditions (Chlorella sp.) with rotifers offered for 10 days (MALR), green water conditions (Chlorella sp.) for 3 days followed by clear water in combination with rotifer feeding for 7 days (AL3R), and clear water conditions with Artemia nauplii offered for 10 days (Art). After the 10‐day feeding, all groups received Artemia nauplii up to 35 days post‐hatching. Larval survival was counted at day 10 and at the end of the 35‐day rearing experiment. At day 35, a significant survival difference was noted between the groups where rotifers were supplemented with algae vs only Artemia. At the end of the experiment, the highest survival rate (69.20%) was obtained with larvae receiving only algae in the first 3 days of feeding. Lowest survival rate (24.90%) was obtained with larvae receiving only Artemia for 35 days. This indicates that smaller prey are essential for burbot at first feeding. Larval length and wet weight were measured at the time of mouth opening, at days 7, 10, and 21, and at the end of the experiment (day 35). On day 35, mean length of the larvae varied significantly between the treatments. However, the final wet weight of the larvae did not vary significantly between the treatments.     

Morphological characterization of adult Artemia (Crustacea, Branchiopoda) from different geographical origins. American populations

The morphological characterization of adult Artemia femalesbelonging to 25 different populations from all over the Americashas been accomplished. The measures of 12 different parametershave been taken from individuals of each population raised understandardized culture conditions from nauplii to adult. Theyhave been analyzed through multivariate discriminant proceduresin order to establish relationships among the different populations,as well as to have a tool to assign new sets of data for unknownpopulations to one of the groups analyzed here. We have beenable to clearly separate the populations of the two differentspecies analyzed (Artemia persimilis and Artemia franciscana).In addition, we distinguish three different clusters of populationsamong the A.franciscana populations: North American athalassicinland populations, individuals from the Caribbean coast areaand populations from the Pacific Ocean shore.     

Larval rearing of chub, Leuciscus cephalus (L.), using decapsulated Artemia as direct food

Little is known about the larviculture of the chub, Leuciscus cephalus (L.), an endangered cyprinid species endemic to European flowing waters. The use of decapsulated Artemia cysts as food for chub larviculture was investigated. After 3‐day feeding with the rotifer Brachionus calyciflorus, the larvae were fed on different diets: (i) dried decapsulated Artemia cysts, (ii) Artemia nauplii, (iii) rotifers for seven more days and then Daphnia collected from a pond, and (iv) an artificial diet. After a 24‐day rearing period, the highest survival rate was obtained with the larvae receiving decapsulated Artemia cysts. Feeding of the larvae with an artificial diet resulted in a significantly lower survival rate compared with the other groups. At the end of the experiment, the larvae fed on Artemia nauplii yielded a significantly higher mean length compared with the other groups. Feeding an artificial diet resulted in a significantly lower average weight and mean length gain compared with the other groups.     

Food-web modification by an invertebrate predator in the Great Salt Lake (USA)

Summary During unusually wet years the salinity of the Great Salt Lake (Utah) decreased from above 100 g/L to 50 g/L. This allowed the predaceous insect Trichocorixa verticalis to invade the pelagic region of the lake and reach a mean summer density of 52/m³. Concurrent changes in the pelagic ecosystem were: a decrease in the dry biomass of the previously dominant filter-feeding brine shrimp Artemia franciscana from 720 to 2 mg/m³, the invasion of three other zooplankton taxa, a 10 × decrease in community filtration rate, a 20 × increase in chlorophyll a concentration, a 4 × decrease in water clarity and perhaps a decrease in soluble nutrients. Trichocorixa abundance was also inversely correlated with the abundance of Artemia along a salinity gradient in the lake's estuary. In a 9-d microcosm experiment Trichocorixa preyed on nauplii and decreased the total density of Artemia from 103 to 6/L. The reduction in Artemia allowed protozoans to increase 10–100 ×. Changes in chlorophyll and clarity were consistent with those observed in the lake. These results suggest that invertebrate predation may be an important factor structuring simple food webs such as those found in moderately saline lakes.     

Fatty acid composition of Turbatrix aceti and its use in feeding regimes of Coregonus maraena (Bloch, 1779): is it really a suitable alternative to Artemia nauplii?

By incorporating the free‐swimming nematode Turbatrix aceti into early feeding regimes of the European whitefish Coregonus maraena, the suitability of this nematode species was investigated as an alternative to Artemia nauplii. During a 14‐day feeding trial in a total of 25 aquaria each 1.7 L (each treatment n = 5, 255 larvae/tank) T. aceti was used either as the sole live food or in combination with Artemia nauplii or microdiet to determine the effect of T. aceti on growth performance and survival rate of C. maraena. By analysing the fatty acid composition of T. aceti prior to and after enrichment with INVE spresso^® it was investigated whether the amount of n3‐polyunsaturated fatty acids (n3‐PUFA) in T. aceti could be further enhanced. Supplementation of Artemia nauplii with T. aceti increased growth significantly within the first 5 days of rearing in comparison to the non‐supplemented food treatments (14.39 ± 0.15 mm compared to 13.44 ± 0.18 mm; mean ± SE). However, growth and survival of juvenile C. maraena on nematode‐supplemented Artemia nauplii did not differ significantly from non‐supplemented Artemia nauplii at the end of the 14‐day rearing period (15.22 ± 0.15 mm compared to 14.86 ± 0.24 mm). All feeding treatments containing Artemia nauplii showed significantly higher growth and lower mortality at the end of the experiment in comparison to diets containing only the microdiet or T. aceti or a combination thereof. The overall low performance of T. aceti alone can most likely be explained by an insufficient capacity of C. maraena to digest this nematode species efficiently. Enrichment with INVE spresso^® successfully increased the proportion of DHA in the T. aceti tissue. The results reveal that T. aceti cannot be considered a full alternative to Artemia nauplii, at least not in the rearing of C. maraena, but might be a useful vector of essential fatty acids within the early rearing period of this and potentially other fish species when provided as live food along with Artemia nauplii.     

Aquaculture related invasion of the exotic <Emphasis Type="Italic">Artemia franciscana</Emphasis> and displacement of the autochthonous <Emphasis Type="Italic">Artemia</Emphasis> populations from the hypersaline habitats of India

Autochthonous parthenogentic Artemia populations have been reported from Indian hypersaline habitats since 1950s. Exotic Artemia franciscana was imported and introduced into India as live food for aquaculture since the early eighties. To assess the present status of the Artemia populations and the possibility of invasion by the introduced A. franciscana in Indian Salinas, an extensive study was conducted using conventional and molecular approaches. Morphological and biometric observations, crossbreeding experiments and molecular and phylogenetic analysis using Internally Transcribed Spacer-1 sequence revealed the extensive presence of alien, sexual A. franciscana populations in various hypersaline areas. Individual culture experiments and crossbreeding studies further confirmed the absence of autochthonous parthenogentic Artemia populations. Lack of regional endemism in populations of distant origins was evident, indicating that the invaded populations have naturalized and are in the process of evolution. This forms the first report of invasion by A. franciscana in hypersaline habitats of Indian subcontinent and further studies are required to assess the biological implications of this invasion.     

The use of a multidisciplinary approach for the characterization of a diploid parthenogenetic Artemia population from Torre Colimena (Apulia, Italy)

A parthenogenetic Artemia population from Torre Colimena, southernItaly, originally reported in 1998, is characterized by a multidisciplinaryapproach including cyst and naupliar biometry, morphometry ofadults, scanning electron microscopy (SEM) of brood pouch, cytogeneticsand 16S rRNA PCR-RFLP analysis. We confirmed parthenogeneticstatus, inferred ploidy level and determined phenotypic andmolecular relationships of this population through comparisonswith other asexual Artemia strains as well as bisexual speciesfound (A. salina) or introduced (A. franciscana) in the Mediterraneanbasin. Cyst and naupliar sizes for Torre Colimena are amongthe smallest recorded for asexual Artemia while the oppositeis true for chorion thickness. Discriminant analysis of adultbody measurements shows increased differentiation (89.5% forthe first four out of the twelve functions produced) from tetraploidparthenogenetic strains and bisexual species (A. salina andA. franciscana). Scanning electron micrographs of brood pouchreveal the characteristic morphology of asexual strains, whilechromosome observations of instar-I nauplii unequivocally establishdiploidy. Restriction patterns give evidence that the TorreColimena population shares an identical set of mitochondrialDNA (mtDNA) polymorphisms with a diploid Spanish parthenogeneticstrain and it is well differentiated from other tetraploid aswell as bisexual auto- and allochthonous strains (A. salinaand A. franciscana) from the Mediterranean. The present studymay serve as a reference methodological framework for multidisciplinarycharacterizations and biodiversity assessments in the genusArtemia.     

Feeding behaviour,feed selectivity and growth studies of mangrove killifish, <Emphasis Type="Italic">Kryptolebias marmoratus</Emphasis>, larvae using various live and formulated feeds

Nine types of live foods viz. L, S and SS morphotypes of Brachionus plicatilis sp. complex, first instar Artemia franciscana, Fabrea salina, Acartia tsuensis, Tigriopus japonicus, Diaphanosoma celebensis, Moina mongolica and a formulated feed of two sizes (400 and 700 μm) were used to observe feeding behaviour and growth of mangrove killifish, Kryptolebias marmoratus. Behavioural observations were made for one hour on days 0, 1, 5, and 10 after hatching. Focus, unsuccessful and successful attacks and vomit were noted. With rotifers L, S and SS types and newly hatched Artemia nauplii as food, all the larvae showed maximum feeding success throughout the experimental period. Larvae did not consume any of the 700 μm artificial diet. Vomiting was noticed on capturing the ciliate Fabrea and 400 μm artificial diets. Rotifers were ingested in greater numbers. SS-type rotifers were consumed in largest number (209.2/h per individual) on day 10. Significantly greater growth was observed after 10 days rearing with L type rotifer, Artemia nauplii, T. japonicus, A. tsuensis, M. mongolica, D. celebensis, and a mixture of L type rotifer and F. salina (Tukey–Kramer post hoc test, P < 0.05). Feed selectivity experiments on days 0, 1, 5 and 10 revealed that killifish larvae feed preferentially on Artemia nauplii and rotifers from a mixture of Artemia nauplii, rotifers, A. tsuensis, T. japonicus, D. celebensis and M. mongolica. Techniques for culturing various zooplankton at small-scales are also described.     

Diversity of extracellular proteases among Aeromonas determined by zymogram analysis

Aims: The current research was aimed at comparing extracellular proteolytic activities and zymogram profiles among Aeromonas spp. Methods and Results: Extracellular proteases of 47 strains of Aeromonas were analyzed by substrate (casein and gelatin) co‐polymerized SDS‐PAGE, and caseinolytic activity was determined using azocasein. Large variation on caseinolytic activity was evidenced. In general, the caseinolytic activity of Aeromonas hydrophila strains was significantly higher than that of other Aeromonas species. Several caseinolytic and gelatinolytic profiles were detected in Aeromonas. Cluster analysis allowed separating Aeromonas strains in four and three groups, based on their caseinolytic and gelatinolytic profiles, respectively. Although not specific patterns were evident, most Aer. hydrophila strains were clustered together and differed from Aeromonas caviae strains. The main caseinases of Aer. hydrophila were a serine protease with an apparent molecular weight (AMW) of 56 kDa and a metalloprotease with AMW of 22 kDa. Gelatinase profiles were characterized by the presence of high molecular weight metalloproteases (84 and 93 kDa), although the most active enzyme was a serine protease with AMW of 56 kDa. Other new caseinases and gelatinases were detected in specific Aeromonas strains. Conclusions: Aeromonas strains exhibited several extracellular proteolytic profiles, with a larger inter than intraspecific variation. Moreover, zymogram analyses allowed identifying new caseinases and gelatinases in Aeromonas. Significance and Impact of the Study: This is the first report on the intra‐ and interspecific variation of proteolytic profiles in Aeromonas determined by zymogram analysis, including the detection of new caseinases and gelatinases in this genus.     

Molecular analysis of autochthonous microbiota along the digestive tract of juvenile grouper Epinephelus coioides following probiotic Bacillus pumilus administration

Aims: To evaluate the diversity of dominant autochthonous microbiota along the digestive tract of juvenile Epinephelus coioides following the dietary administration of probiotic Bacillus pumilus for 60 days. Methods and Results: Polymerase chain reaction‐denaturing gradient gel electrophoresis (PCR‐DGGE) with subsequently sequencing analysis was used to assess the gut microbiota. Generally similar DGGE patterns were observed in the foregut, midgut and hindgut of E. coioides, while the similarity dendrogram clearly revealed three different clusters depending on the three compartments of the GI tract. Dietary administration of B. pumilus stimulated its colonization in each compartment of the digestive tract. Samples collected from the probiotic group and the control group showed similar DGGE patterns, and no significant difference in the total number of bands and the Shannon index were detected between the probiotic group and the control group, suggested that B. pumilus exert no significant effect on the gut microbiota. However, various potentially beneficial bacteria, such as uncultured Bacillus sp. clone QJNY94‐like, Nitratireductor sp. YCSC5‐like, Methylobacterium hispanicum‐like and Microbacterium sp. YACS1‐like bacteria were stimulated by probiotic B. pumilus, while the potential harmful Staphylococcus saprophyticus‐like bacterium was depressed. Conclusions: Autochthonous gut microbiota of E. coioides was modulated to some degree, not significant, by probiotic B. pumilus, various potentially beneficial bacteria were selectively stimulated, while one potential harmful species was depressed. Significance and Impact of the Study: This work represents the first report that dietary administration of probiotic B. pumilus modulated the gut microbiota of E. coioides. These findings broaden our understanding of probiotic effects at the gut level, which is helpful in understanding the mechanisms that underpin host benefits.