Functional Characterization of Probiotic Potential of Novel Pigmented Bacterial Strains for Aquaculture Applications

Abstract

The bioprospecting proficient of novel pigmented probiotic strains with respect to aquaculture industry was unexplored hitherto. In this study, we investigated the probiotic potential of novel pigmented bacterial strains isolated from the indigenous soil sediments in their vicinal habitats, which were screened for their antimicrobial activity against aquatic pathogens using agar well diffusion assay. The strains namely Exiguobacterium acetylicum (S01), Aeromonas veronii (V03), and Chryseobacterium joostei (V04) were phenotypically identified and confirmed by 16S rRNA gene sequence analysis. Further characterization revealed that strains S01 and V03 survive relatively in lower pH and higher bile salt concentrations and possess good adherence ability and broad-spectrum antibiotic susceptibility. The isolate S01 exhibited the higher adhesion ability to hydrocarbons (82%) and mannose-specific adhesion (msa) gene expression. Additionally, the probiotic effects were evaluated in Artemia nauplii fed with algae supplemented with S01, V03, and V04 strains (2.7 × 10 cfu/mL) for 3 days under axenic environment. We observed a significant increase (p < 0.05) in the survival rate of Artemia nauplii treated with S01 (83 ± 5%) and V03 (55 ± 5%), whereas the survival rate was only 30 ± 0% in the untreated group. Moreover, the individual length (IL) was increased in treated group S01 (156.7 ± 2.2 μm), V03 (146.1 ± 3.4 μm), and V04 (134.4 ± 2.5 μm) compared with untreated group (116.0 ± 4.8 μm). Our results revealed that E. acetylicum S01 exhibits desirable functional probiotic attributes compared to A. veronii and C. joostei and it would be a promising probiotic strain, which can be efficiently used in the aquaculture applications.

Induction of mitochondria-mediated apoptosis and suppression of tumor growth in zebrafish xenograft model by cyclic dipeptides identified from Exiguobacterium acetylicum

“…Bacterial strain, extraction, and purification of bioactive compounds. Strain E. acetylicum S01 was genetically confirmed by 16S ribosomal RNA gene sequencing, and it showed desirable functional probiotic attributes and provided disease resistance against Aeromonas hydrophila infection in goldfish (Carassius auratus) as described earlier 47,48 . For identification and characterization of bioactive compound(s), a loopful culture of E. acetylicum S01 was grown in Luria-Bertani broth (LB) (casein enzymatic hydrolysate 10 g/L, yeast extract 5 g/L, sodium chloride 10 g/L, pH 7.5 ± 0.2, water 1,000 mL) and incubated on a rotary shaker (120 rpm) at 37 °C.…”

Bacterial Diversity and Antibiotic Susceptibility of Sparus aurata from Aquaculture

“…Species like Bacillus spp., E. acetylicum and Enterococcus spp. can be used as probiotics in aquaculture to reduce antibiotic consumption and avoid the spread of antibiotic resistance genes [ 66 , 89 , 90 ]. We could not obtain information if this was the case of this fish farming pilot station, in Portugal, possibly justifying the presence of these bacteria in our samples.…”

Optimization of submerged fermentation process for improved production of β-carotene by Exiguobacterium acetylicum S01

“…The potential probiotic bacterium E. acetylicum S01 (accession number KU058431.1) was isolated from a soil sample collected from the Sathaiyar river basin in the Madurai region, Tamil Nadu, India as described previously (Jinendiran et al., 2017). It was cultured and maintained on nutrient agar (HiMedia, AS061) slant at 4 °C and sub-cultured monthly.…”

“…However, the optimization of β-carotene production by Exiguobacterium acetylicum S01 using statistical design has not yet been studied extensively but requires further detailed exploration. We have previously reported the isolation and functional characterization of pigmented probiotic strain E. acetylicum S01 (Jinendiran et al., 2017). Hence, the present study aimed to investigate the effects of medium components (MCs) and essential physical factors (PFs) on β-carotene and biomass productivity and additionally to investigate a suitable medium for maximizing the β-carotene production by E. acetylicum S01 based on a sequential statistical experimental design approach.…”