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Lactococcus lactis as a safe and inexpensive source of bioactive silver composites.

ABSTRACT: This research develops a safe, inexpensive, and more accessible source for synthesis of silver nanoparticles. The bioactive silver composites synthesized by Lactococcus lactis 56 KY484989 (LCLB56-AgCs) were characterized by various physico-chemical techniques and investigated for their antimicrobial activity and cytotoxicity. The average amount of nanoparticles was 0.363 ± 0.09 mg from 50 mL of culture medium. The synthesis efficiency varied from 71 to 85%. Synthesized silver nanoparticles with spherical in shape were found to be of 5-50 nm and average diameter 19 ± 2 nm. Based on the shape of isotopic pattern of d-electrons metals, the signals of silver isotopes [¹⁰⁷Ag]⁺ at m/z 106.905 and [¹⁰⁹Ag]⁺ at m/z 108.910 were confirmed. Moreover, LCLB56-AgCs exerted an inhibitory effect against all tested bacterial strains (Pseudomonas aeruginosa ATCC10145, Proteus mirabilis ATCC25933, Staphylococcus epidermidis ATCC49461, MSSA ATCC29213, and Staphylococcus aureus ATCC6338). More pronounced antimicrobial effect was noticed for 15 μg/well. Minimum inhibitory concentration required to inhibite the growth of 90% organism (MIC₉₀) of synthetized LCLB56-AgCs was in a range of 3.125-12.5 μg/mL. The concentration at which the viability of the L929 cells was reduced to 50% was above 200 μg/mL for LCLB56-AgNCs. These results open up possibilities for many applications of bioactive silver composites (BioAgCs) synthesized by L. lactis 56 in food and pharmaceutical industries.

SUBMITTER: Viorica RP

PROVIDER: S-EPMC5594055 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Large-scale mass spectrometry-based peptidomics for bioactive-peptide discovery is relatively unexplored because of challenges in intracellular peptide extraction and small-peptide identification. Here, we present an analytical pipeline for large-scale intracellular peptidomics of Lactococcus lactis It entails an optimized sample preparation protocol for L. lactis, used as an "enzyme complex" to digest ?-casein, an extraction method for its intracellular peptidome, and a peptidomics data analysis and visualization procedure. In addition, we proofread the publicly available bioactive-peptide databases and obtained an optimized database of bioactive peptides derivable from bovine ?-casein. We used the pipeline to examine cultures of L. lactis MG1363 and a set of 6 isogenic multiple peptidase mutants incubated with ?-casein. We observed a clearly strain-dependent accumulation of peptides with several bioactivities, such as angiotensin-converting enzyme (ACE)-inhibitory, dipeptidyl peptidase 4 (DPP-IV)-inhibitory, and immunoregulatory functions. The results suggest that both the number of different bioactive peptides and the bioactivity diversity can be increased by editing the proteolytic system of L. lactis This comprehensive pipeline offers a model for discovery of bioactive peptides in combination with other proteins and might be applicable to other bacteria.IMPORTANCE Lactic acid bacteria (LAB) are very important for the production of safe and healthy human and animal fermented foods and feed and, increasingly more, in the functional food industry. The intracellular peptidomes of LAB are promising reservoirs of bioactive peptides. We show here that targeted genetic engineering of the peptide degradation pathway allows steering the composition of the peptide pool of the LAB Lactococcus lactis and production of peptides with interesting bioactivities. Our work could be used as a guideline for modifying proteolytic systems in other LAB to further explore their potential as cell peptide factories.

Project description:Objective: Modulation of the dysbiotic gut microbiome with "healthy" bacteria via a stool transplant or supplementation is increasingly practiced, however this approach has not been explored in the nasal passages. We wished to verify whether Lactococcus lactis W136 (L. lactis W136) bacteria could be safely applied via irrigation to the nasal and sinus passages in individuals with chronic rhinosinusitis (CRS) with previous undergone endoscopic sinus surgery, and whether this was accompanied by bacterial community flora modification. Study Design: Prospective open-label pilot trial of safety and feasibility. Setting: Academic tertiary hospital center. Subjects and Methods: Twenty-four patients with CRS refractory to previous medical and surgical therapy received a 14-day course of BID sinus irrigations containing 1.2 × 109 CFU live L. lactis W136. Patients were monitored for safety using questionnaire, sinus endoscopy, otoscopy, UPSIT-40 smell testing, and endoscopically-obtained conventional sinus culture and a swab for 16S microbiome profiling. Results: All 24 patients receiving at least one treatment successfully completed treatment. L. lactis W136 probiotic treatment was safe, with no major adverse events or new infections. Treatment was associated with improvement in sinus symptoms, QOL, and mucosal scores, which remained improved during the subsequent 14-day observation period. Microbiome changes associated with treatment were limited to an increase of the pathobiont Dolosigranulum pigrum, a bacteria identified as potentially beneficial in the upper airways. Subgroup analysis suggested differences in microbiomes and responses for CRSsNP and CRSwNP phenotypes, but these did not attain significance. Conclusion: Intranasal irrigation of live L. lactis W136 bacteria to patients with refractory chronic rhinosinusitis was safe, and was associated with effects on symptoms, mucosal aspect and microbiome composition. Intranasal bacteria may thus find a role as a treatment strategy for CRS. Clinical Trials Registration: www.ClinicalTrials.gov. identifier: NCT04048174.

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Lactococcus lactis as a safe and inexpensive source of bioactive silver composites.

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