Gene transfer in soil systems using microcosms

Hill, Katja E.; Top, Eva M.

doi:10.1111/j.1574-6941.1998.tb00483.x

Cited by 70 publications

(18 citation statements)

References 54 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It has been reported that the chlorination process in sewage treatment can also contribute to the selection of ARB (56), and some β-lactam-resistant genes ( bla TEM and AmpC genes) could be enriched through chlorination (49). In addition, our results demonstrated that Amp resistance displayed the highest transfer potential among all the detected antibiotics (Table 4), and Amp resistance in site N1, N4 and N5 may be accelerated owing to the high level of nutrients (28). As can be seen from CCA analysis, the antibiotic resistance profile of N1, N4 and N5 clustered together and was separate from other sites (Fig.…”

Section: Discussionmentioning

confidence: 73%

Occurrence and Distribution of Antibiotic-resistant Bacteria and Transfer of Resistance Genes in Lake Taihu

et al. 2013

View full text Add to dashboard Cite

The overuse of antibiotics has accelerated antibiotic resistance in the natural environment, especially fresh water, generating a potential risk for public health around the world. In this study, antibiotic resistance in Lake Taihu was investigated and this was the first thorough data obtained through culture-dependent methods. High percentages of resistance to streptomycin and ampicillin among bacterial isolates were detected, followed by tetracycline and chloramphenicol. Especially high levels of ampicillin resistance in the western and northern regions were illustrated. Bacterial identification of the isolates selected for further study indicated the prevalence of some opportunistic pathogens and 62.0% of the 78 isolates exhibited multiple antibiotic resistance. The presence of ESBLs genes was in the following sequence: blaTEM > blaSHV > blaCTMX and 38.5% of the isolates had a class I integrase gene. Of all tested strains, 80.8% were able to transfer antibiotic resistance through conjugation. We also concluded that some new families of human-associated ESBLs and AmpC genes can be found in natural environmental isolates. The prevalence of antibiotic resistance and the dissemination of transferable antibiotic resistance in bacterial isolates (especially in opportunistic pathogens) was alarming and clearly indicated the urgency of realizing the health risks of antibiotic resistance to human and animal populations who are dependent on Lake Taihu for water consumption.

show abstract

Section: Discussionmentioning

confidence: 73%

Occurrence and Distribution of Antibiotic-resistant Bacteria and Transfer of Resistance Genes in Lake Taihu

et al. 2013

View full text Add to dashboard Cite

show abstract

“…The actual concentrations of antibiotics in natural soils are unclear to date and di¤cult to estimate, since, with few exceptions, antibiotics are rarely isolated from soil [220^222]. Potential ecological interactions and factors that are important for the transfer process are not evaluated unless natural conditions are mimicked by the use of soil-plant microcosms [256,257]. A low sensitivity is expected due to di¡erences in cultivation requirements for soil bacteria, the level of acquired resistance to the selecting agent, e¤ciency of plating, and interference from the natural background of resistant bacteria to the selective agent, i.e.…”

Section: Selection and Environmental Impact Of Bacterial Transformantsmentioning

confidence: 99%

Horizontal gene transfer from transgenic plants to terrestrial bacteria – a rare event?

Nielsen¹

1998

FEMS Microbiology Reviews

View full text Add to dashboard Cite

Today, 12 years after the first field release of a genetically modified plant (GMP), over 15,000 field trials at different locations have been performed. As new and unique characteristics are frequently introduced into GMPs, risk assessment has to be performed to assess their ecological impact. The possibilities of horizontal gene transfer (HGT; no parent-to-offspring transfer of genes) from plants to microorganisms are frequently evaluated in such risk assessments of GMPs before release into the field. In this review we indicate why putative HGT from plants to terrestrial (soil and plant associated) bacteria has raised concern in biosafety evaluations. Further, we discuss possible pathways of HGT from plants to bacteria, outline the barriers to HGT in bacteria, describe the strategies used to investigate HGT from plants to bacteria and summarize the results obtained. Only a few cases of HGT from eukaryotes such as plants to bacteria have been reported to date. These cases have been ascertained after comparison of DNA sequences between plants and bacteria. Although experimental approaches in both field and laboratory studies have not been able to confirm the occurrence of such HGT to naturally occurring bacteria, recently two studies have shown transfer of marker genes from plants to bacteria based on homologous recombination. The few examples of HGT indicated by DNA sequence comparisons suggest that the frequencies of evolutionarily successful HGT from plants to bacteria may be extremely low. However, this inference is based on a small number of experimental studies and indications found in the literature. Transfer frequencies should not be confounded with the likelihood of environmental implications, since the frequency of HGT is probably only marginally important compared with the selective force acting on the outcome. Attention should therefore be focused on enhancing the understanding of selection processes in natural environments. Only an accurate understanding of these selective events will allow the prediction of possible consequences of novel genes following their introduction into open environments.

show abstract

“…As we discuss below, and was pointed out in Simonsen et al (1990), this leads to some of these measures of plasmid transfer being highly sensitive to sampling time. Thus, while these measures give some indication of the efficiency of transfer, they do not directly report the rate or frequencies of the conjugative transfer events and are significantly confounded by growth of T , R , and D during the course of an experiment (often several hours, or even days for studies in microcosms or the field) (Simonsen et al, 1990; Hill and Top, 1998; van Elsas and Bailey, 2002). …”

Section: Introductionmentioning

confidence: 99%

On the meaning and estimation of plasmid transfer rates for surface-associated and well-mixed bacterial populations

Zhang

Droesch

Fox

et al. 2012

Journal of Theoretical Biology

View full text Add to dashboard Cite

Conjugative plasmid transfer is key to the ability of bacteria to rapidly adapt to new environments, but there is no agreement on a single quantitative measure of the rate of plasmid transfer. Some studies derive estimates of transfer rates from mass-action differential equation models of plasmid population biology. The often-used ‘endpoint method’ is such an example. Others report measures of plasmid transfer efficiency that simply represent ratios of plasmid-bearing and plasmid-free cell densities and do not correspond to parameters in any mathematical model. Unfortunately, these quantities do not measure the same thing – sometimes differing by orders of magnitude – and their use is often clouded by a lack of specificity. Moreover, they do not distinguish between bulk transfer rates that are only relevant in well-mixed populations and the ‘intrinsic’ rates between individual cells. This leads to problems for surface-associated populations, which are not well-mixed but spatially structured. We used simulations of a spatially explicit mathematical model to evaluate the effectiveness of these various plasmid transfer efficiency measures when they are applied to surface-associated populations. The simulation results, supported by some experimental findings, showed that these measures can be affected by initial cell densities, donor-to-recipient ratios and initial cell cluster size, and are therefore flawed as universal measures of plasmid transfer efficiency. The simulations also allowed us to formulate some guiding principles on when these estimates are appropriate for spatially structured populations and how to interpret the results. While we focus on plasmid transfer, the general lessons of this study should apply to any measures of horizontal spread (e.g., infection rates in epidemiology) that are based on simple mass-action models (e.g., SIR models in epidemiology) but applied to spatial settings.

show abstract

Gene transfer in soil systems using microcosms

Cited by 70 publications

References 54 publications

Occurrence and Distribution of Antibiotic-resistant Bacteria and Transfer of Resistance Genes in Lake Taihu

Occurrence and Distribution of Antibiotic-resistant Bacteria and Transfer of Resistance Genes in Lake Taihu

Horizontal gene transfer from transgenic plants to terrestrial bacteria – a rare event?

On the meaning and estimation of plasmid transfer rates for surface-associated and well-mixed bacterial populations

Contact Info

Product

Resources

About