Characteristics of N-Acylhomoserine Lactones Produced by Hafnia alvei H4 Isolated from Spoiled Instant Sea Cucumber

Abstract

This study aimed to identify N-acylhomoserine lactone (AHL) produced by Hafnia alvei H4, which was isolated from spoiled instant sea cucumber, and to investigate the effect of AHLs on biofilm formation. Two biosensor strains, Chromobacterium violaceum CV026 and Agrobacterium tumefaciens KYC55, were used to detect the quorum sensing (QS) activity of H. alvei H4 and to confirm the existence of AHL-mediated QS system. Thin layer chromatography (TLC) and high resolution triple quadrupole liquid chromatography/mass spectrometry (LC/MS) analysis of the AHLs extracted from the culture supernatant of H. alvei H4 revealed the existence of at least three AHLs: N-hexanoyl-l-homoserine lactone (C6-HSL), N-(3-oxo-octanoyl)-l-homoserine lactone (3-oxo-C8-HSL), and N-butyryl-l-homoserine lactone (C4-HSL). This is the first report of the production of C4-HSL by H. alvei. In order to determine the relationship between the production of AHL by H. alvei H4 and bacterial growth, the β-galactosidase assay was employed to monitor AHL activity during a 48-h growth phase. AHLs production reached a maximum level of 134.6 Miller unites at late log phase (after 18 h) and then decreased to a stable level of about 100 Miller unites. AHL production and bacterial growth displayed a similar trend, suggesting that growth of H. alvei H4 might be regulated by QS. The effect of AHLs on biofilm formation of H. alvei H4 was investigated by adding exogenous AHLs (C4-HSL, C6-HSL and 3-oxo-C8-HSL) to H. alvei H4 culture. Biofilm formation was significantly promoted (p < 0.05) by 5 and 10 µM C6-HSL, inhibited (p < 0.05) by C4-HSL (5 and 10 µM) and 5 µM 3-oxo-C8-HSL, suggesting that QS may have a regulatory role in the biofilm formation of H. alvei H4.

Droplet-based high-throughput cultivation for accurate screening of antibiotic resistant gut microbes

“…which were the predominant population in droplets across all three rich media and the growth dynamics of at least some strains of Hafnia alvei are modulated by quorum sensing [45]. Combined, these droplet benefits -high-throughput, reduction of competition, and increase in quorum sensing -likely led to the improvement in droplet-grown representation.…”

“…Although we do not know the total extent to which quorum sensing is utilized by droplet-grown bacteria, one likely candidate is Hafnia spp. which were the predominant population in droplets across all three rich media and the growth dynamics of at least some strains of Hafnia alvei are modulated by quorum sensing ( Hou et al, 2017 ). Combined, these droplet benefits – high-throughput, reduction of competition, and increase in quorum sensing – likely led to the improvement in droplet-grown representation.…”

High-throughput isolation and sorting of gut microbes reduce biases of traditional cultivation strategies

“…Potentially, quorum sensing mediated growth could explain the predominant abundance of Hafnia spp. in droplets across all three rich media, since the growth dynamics of at least some strains of Hafnia alvei are modulated by quorum sensing [36].…”

Quorum Sensing and Spoilage Potential of Psychrotrophic Enterobacteriaceae Isolated from Milk

“…This result agrees with those from Bruhn [ 30 ] who verified that this same HSL was predominant among four AHLs produced by H. alvei isolated from vacuum-packed meat. However, Hou [ 34 ] detected C4-HSL, C6-HSL, and 3-oxo-C8-HSL in culture supernatants of H. alvei H4 isolated from spoiled sea cucumber, revealing the diversity of signaling molecules in H. alvei species.…”