Appraisal of cytotoxicity and acrylamide mitigation potential of L-asparaginase SlpA from fish gut microbiome.

L-asparaginase catalyzes the hydrolysis of L-asparagine to L-aspartic acid and ammonia. It has application in the treatment of acute lymphoblastic leukemia in children, as well as in other malignancies, in addition to its role as a food processing aid for the mitigation of acrylamide formation in the baking industry. Its use in cancer chemotherapy is limited due to problems such as its intrinsic glutaminase activity and associated side effects, leading to an increased interest in the search for novel L-asparaginases without L-glutaminase activity. This study reports the cloning and expression of an L-asparaginase contig obtained from whole metagenome shotgun sequencing of Sardinella longiceps gut microbiota. Purified recombinant glutaminase-free L-asparaginase SlpA was a 74 kDa homodimer, with maximal activity at pH 8 and 30 °C. Km and Vmax of SlpA were determined to be 3.008 mM and 0.014 mM/min, respectively. SlpA displayed cytotoxic activity against K-562 (chronic myeloid leukemia) and MCF-7 (breast cancer) cell lines with IC50 values of 0.3443 and 2.692 U/mL, respectively. SlpA did not show any cytotoxic activity against normal lymphocytes and was proved to be hemocompatible. Pre-treatment of biscuit and bread dough with different concentrations of SlpA resulted in a clear, dose-dependent reduction of acrylamide formation during baking. KEY POINTS: • Cloned and expressed L-asparaginase (SlpA) from fish gut microbiota • Purified SlpA displayed good cytotoxicity against K-562 and MCF-7 cell lines • SlpA addition caused a significant reduction of acrylamide formation during baking.

Indian oil sardine (Sardinella longiceps) gut derived Bacillus safensis SDG14 with enhanced probiotic competence for food and feed applications.

Probiotics are considered as functional food as they provide health benefits along with traditional nutrition. Spore forming probiotic Bacillus are of commercial interest than Lactic Acid Bacillus due to their relatively lower cost of production and higher survivability. In the present study we identified the bacterial strain SDG14 isolated from Indian oil Sardine by Average Nucleotide Identity of whole genome sequence. The whole genome of SDG14 was also explored for pathogenicity, the presence of genes responsible for probiotic traits such as spore formation, resistance to host gastrointestinal tract conditions, adhesion to intestinal mucosa, interference in pathogen survival, expression of bacteriocins, oxidative and other stress responses, absorption of nutrition, production of essential amino acids and vitamins. Wet lab experiments for probiotic characterization were also conducted. The organism was confirmed to be Bacillus safensis SDG14. The possible pathogenicity of the organism was also ruled out by in silico analysis. Bacillus safensis SDG14 was able to survive at pH 3 and bile salt concentration of 0.5% (w/v). The adhesion index of Bacillus safensis SDG14 on HEp-2 was 36.82 ± 5.93 and 45.54 ± 9.55 respectively after 60 and 90 min of incubation and self aggregation percentage was 18.4 ± 0.48% after 3 h. Bacillus safensis SDG14 produced bacteriocin and co-aggregated with E. coli, Salmonella Typhimurium and Pseudomonas aeruginosa. The genomic data supported the findings of wet lab study and vice versa. Bacillus safensis SDG14 was proved to be a non-pathogenic, spore forming, pH and bile salt resistant, bacteriocin, amino acid and vitamin producing probiotic with proposed food and feed applications.

A magainin-2 like bacteriocin BpSl14 with anticancer action from fish gut Bacillus safensis SDG14.

Bacteriocins are gaining utmost importance in antimicrobial and chemotherapy due to their diverse structure and activity. This study centres on magainin-2 like bacteriocin with anticancer action, produced by Bacillus safensis strain SDG14 isolated from gut of marine fish Sardinella longiceps. The purified bacteriocin designated as BpSl14 was thermostable and pH tolerant. The molecular weight of BpS114 was estimated to be 6061.2 Da using MALDI-ToF MS. The partial primary sequence was elucidated by peptide mass fingerprinting using MALDI MS/MS. The tertiary structure of the partial sequence was similar to that of two magainin-2 α-helices joined together by extended indolicidin. The BpSl14 protein inhibited the cells of lung carcinoma, one of the deadliest cancers. Docking studies conducted with DR5 and TGF-ß, two of the most prominent apoptotic receptors in adenocarcinoma, also proved the anti-apoptotic action of BpSl14.

Metabarcoding data of bacterial diversity of the deep sea shark, Centroscyllium fabricii.

This data article describes the bacterial diversity of the deep sea shark, Centroscyllium fabricii. The data was acquired by metabarcoding using 16S rDNA. Centroscyllium fabricii, a deep sea shark found at depths below 275 m was sampled during Sagar Sampada cruise no 305 in the Indian Ocean and metagenomic DNA was isolated from the gut contents using QIAamp DNA stool minikit. V3 region of 16S rDNA region was amplified and the amplicons were sequenced on Illumina MiSeq system using 151 bp × 2 paired end reads. The data of this metagenome is available in the BioSample Submission Portal as Bio-Project PRJNA431407and Sequence Read Archive (SRA) accession number SRR6507004.