Generalized gene transfer by virus-like particles from marine bacteria

Abstract

Spontaneous VLP (virus-like particle) production and VLP-mediated gene transfer into Escherichia coli AB1157 as recipient was demonstrated. Five marine isolates (Alc 096, Alc 233, Alc 252, Agrobacterium kieliense and Flavobacterium sp. 11604) were investigated for their potential to produce VLP as well as for the gene transfer capability of these VLPs to the E. col1 recipient. These strains are classified as ubiquinone-10-possessing marine bacteria (QIOMB) in the 16s-rRNA Superfamily IV VLPs were obtained from 100 h cultured broth of all strains examined. VLP-host ratio after 100 h growth culture was: Alc 233, 1.54; Alc 252, 1.26; Alc 096, 1.06; Flavobacterjum sp. 11604, 0.69; and A. kieliense, 0.06. These ratios were smaller than those found in the marine environment. However, the spontaneously produced VLP number can be considered as high because the reported numbers are relatively low from coliphage h (0.005) and phage Mu (-0.0001). VLP-mediated gene transfer was examined using an auxotrophic mutant of E. coli (AB1157) with 4 amino acid deficiencies (leu, pro, his, arg)as recipient at multiplicity of infection (MOI) of 0.1. Through this treatment, VLPs showed lethal effect on the recipient. The survival rate of control was: Alc 096, 7%; Alc 252, 8 % ; A. kieliense, 17%; Flavobacterium sp. 11604,31%; and Alc 233,40%. At the same time, all the purified VLPs derived from these 5 strains successfully transferred genes to rescue genetlc defects of the recipi.ent. Overall average efficiency of VLP-mediated gene transfer at MO1 of 0.1 was estimated to be between 2.62 X' 10-3 and 3.58 X 10-'per VLP particle. Loci of employed genetic markers were dispersed on the E. coli chromosome with mutual distance of 121, 1154, 1397 and 364 kb between them. Since VLPs from different sources showed similar gene transfer efficiency in respect to the genet~c marker rescued, it is suggested that VLPs from QlOMB transferred genes as generalized transduction. These results indicate that the VLPs produced by certain marine bacteria may be an important element for both non-specific generalzed horizontal gene transfer towards a broad range of bacterial hosts and population control in the marine environment.

Broad-Host Range Gene Transporter Particles Produced by Aliivibrio fischeri

“…Nucleic acid and protein contents of AfVP in the final specimen were 4.010 mg and 101.764 mg, which corresponded to 29.8% and 35.8% of the initial values, respectively. The ratio of protein per nucleic acid was 24.9, comparable to values reported to date (3,(5)(6)(7)(8)(9)(10). Another feature of AfVP is its coagulating behaviour.…”

“…Regardless of UV irradiation, VPs exhibit a mildly lethal effect (maximum, 10%) towards a taxonomically broad range of recipients without plaque formation. VPs (3)(4)(5)(6)(7)(8)(9)(10) do not fit the current concept of a "virus" with a narrow host range (1). Although the DNA-encapsulating system of VP is still unclear, these characteristics supports the possibility that VP-mediated transduction enhances microbial differentiation and evolution.…”

“…AfVP production was accompanied by mucoidal substances (Fig. 1E, Dull shape of particles surrounding the cell), a trait observed in marine strains (3,5), which reduced the rate of recovery using a tangential flow concentration system (0.2 μm>parti-cle>100 kDa). Namely, 1.08×10 15 particles were recovered, corresponding to 39% of the initial number.…”

“…We have demonstrated that VLPs released spontaneously into culture medium from some marine bacterial isolates show a gene transfer capability, with a lethal effect on recipients distantly related to their original host (3)(4)(5). These VLPs contain DNA, and are similar morphologically to viruses (3)(4)(5).…”

“…These VLPs contain DNA, and are similar morphologically to viruses (3)(4)(5). We have proposed calling such particles "broad-hostrange vector particles" (VPs) because of their extraordinary properties.…”