Antimicrobial properties of mucus from the brown garden snail Helix aspersa

Abstract

Research into naturally occurring antimicrobial substances has yielded effective treatments. One area of interest is peptides and proteins produced by invertebrates as part of their defence system, including the contents of mollusc mucous. Mucous produced by the African giant land snail, Achatina fulica has been reported to contain two proteins with broad spectrum anti-bacterial activity. Mucous from the brown garden snail, Helix aspersa appears to have skin regenerationproperties. This study sought to investigate the antimicrobial properties of H.aspersa mucous.Mucous was collected from H.aspersa snails, diluted in PBS and centrifuged, with the supernatant tested against a wide range of organisms in a disc diffusion antimicrobial assay. This was followed up with comparative experiments involving A.fulica , including bacteriophage assays. Mucous from both species of snail was passed through a series of protein size separation columns in order to determine the approximate size of the antimicrobial substance. Electrophoresis was also carried out on the H.aspersa mucous.Results indicated that H.aspersa mucous had a strong antibacterial effect against several strains of Pseudomonas aeruginosa and a weak effect against Staphylococcus aureus. Mucous from A.fulica also inhibited the growth of S.aureus, but the broad spectrum of activity reported by other workers was not observed. Antimicrobial activity was not caused by bacteriophage. Size separation experiments indicated that the antimicrobial substance(s) in H.aspersa were between 30 and 100 kDa. Electrophoresis revealed two proteins in this region -30-40 kDa and 50-60kDa. These do not correspond with antimicrobial proteins previously reported in A.fulica. This study found one or more novel antimicrobial agents in H.aspersa mucous, with a strong effect against P.aeruginosa . 2

British Journal of Biomedical Science in 2016. What have we learned?

“…This promising result lends support to the view that plant products represent a new opportunity to counter antibiotic resistance [50]. Last year, Pitt et al [51] presented data that an extract of mucus from a snail has antimicrobial activity, a finding confirmed and extended by Bortolotti et al [52] in three common bacteria and Candida albicans. They also provided safety data in that their mucus extract had no critical effect on a transformed human T lymphocyte cell line in vitro.…”

Antimicrobial Activities of Different Fractions from Mucus of the Garden Snail Cornu aspersum

“…This has prompted intense studies of invertebrate species in the last few years. Most of the AMPs found in the hemolymph of invertebrates show activity against a mix of microorganisms including bacteria, viruses, and protozoa [12][13][14][15].…”

British Journal of Biomedical Science in 2019. What have we learned?

“…Bakhti and colleagues used molecular genetics to show that cagH, cagL, and orf17 are linked (p = 0.046, p = 0.004, p = 0.01, respectively) to any upper intestinal ulceration, whilst cagG is linked to duodenal, not gastric, ulceration (p = 0.007) [59]. Pitt and colleagues gave us an update [60] on their pursuit of the antibiotic potential of snail mucus, reporting a number of proteins that inhibit the growth of Pseudomonas aeruginosa, the most promising being a 37.4 kDa molecule named Aspernin [61]. The next step in getting Aspernin to the hospital pharmacity is to determine its toxicity, first in cell lines, and then to determine biological activity in an animal model of infection, a pathway that may take a decade to complete.…”