NAXOS2018 2018-06-13 Background Antibiotics crisis Antibiotic - - PowerPoint PPT Presentation

Antibiotic resistance genes variation pattern during swine manure composting under different aeration strategies

JIALI CHANG LESHAN NORMAL UNIVERSITY 6th International Conference on Sustainable Solid Waste Management

2018-06-13

NAXOS2018

Background

(Jim O’Neill, 2016)

Antibiotics crisis

Antibiotic resistance genes (ARGs) Emerging environmental contaminants

Background

(Zhang Qianqian, et al., 2016)

Background

 Diverse, abundant, and potentially mobile ARGs in farm samples suggest that unmonitored use of antibiotics is causing the emergence and release of ARGs to the environment.

(Zhu yongguan, et al., 2012)

Scientific problems Whether ARGs were eliminated or enriched after composting? How composting aeration methods influence the ARGs variation pattern?

Materials and methods

• Cornstalk

air dried and chopped to ~ 5 -10 cm;

• Pig faeces

from Ganqingfen system of a local pig farm.

Samples TOC (g·kg-1) TN (g·kg-1) Ammonium (g·kg-1) Moisture content (%) C/N Pig faeces 343.7 26.5 7.4 71.8 13.0 Cornstalk 419.0 9.9 — 9.3 42.3 Mixture 367.4 21.2 5.7 63.6 17.3

Raw materials

Materials and methods

• Materials were composted in 1.2 m3

bins for 10 week.

• Total 5 treatments:

Static, Turn, Forced aeration.

• Turning frequency is 1/week.
• Aeration rate is 0.05/0.1/0.25

L·kgDM-1·min-1.

Composting methods

1 2 3 4 5

• 1. Wooden boards with sampling holes;
• 2. Concrete side wall;
• 3. Concrete floor and aeration and

leachate cavum;

• 4. Bottom board with aeration holes;
• 5. Compost materials.

20 40 60 80 7 14 21 28 35 42 49 56 63 70 77 Temperature (℃) Composting time (d) Aeration-0.05 Aeration-0.1 Aeration-0.25 Turn windrow Static pile Air

Materials and methods Sampling for ARGs and microbial analysis

 Quantitative polymerase chain reaction (qPCR)  Highthroughput sequencing via Illumina Miseq platform tetW/tetO/tetH suII/sulII qnrS ermB blaTEM intI General bacteria 16S rRNA gene

Results_ ARGs

0% 20% 40% 60% 80% 100% Origin Aeration‐0.25 Aeration‐0.1 Aeration‐0.05 Turn Static Aeration‐0.25 Aeration‐0.1 Aeration‐0.05 Turn Static Aeration‐0.25 Aeration‐0.1 Aeration‐0.05 Turn Static Relative abundances of each ARG tetW tetO tetH sulII sulI qnrS intI ermB blaTEM

Day 21 Day 49 Day 77

Diversity patterns of the representative ARGs during the whole composting process among 5 different aeration methods

Results_ ARGs

1.0E+04 1.0E+06 1.0E+08 1.0E+10 1.0E+12

blaTEM

1.0E+04 1.0E+06 1.0E+08 1.0E+10 1.0E+12

ermB

1.0E+04 1.0E+06 1.0E+08 1.0E+10 1.0E+12

qnrS

1.0E+04 1.0E+06 1.0E+08 1.0E+10 1.0E+12

tetH tetO tetW

1.0E+04 1.0E+06 1.0E+08 1.0E+10 1.0E+12 Origin Aeration‐0.25 Aeration‐0.1 Aeration‐0.05 Turn Static Aeration‐0.25 Aeration‐0.1 Aeration‐0.05 Turn Static Aeration‐0.25 Aeration‐0.1 Aeration‐0.05 Turn Static

sulI sulII

1.0E+04 1.0E+06 1.0E+08 1.0E+10 1.0E+12 Origin Aeration‐0.25 Aeration‐0.1 Aeration‐0.05 Turn Static Aeration‐0.25 Aeration‐0.1 Aeration‐0.05 Turn Static Aeration‐0.25 Aeration‐0.1 Aeration‐0.05 Turn Static

intI

a

ND ND ND ND

b c d e f

Day 21 Day 49 Day 77 Day 21 Day 49 Day 77

ARGs copies per g dry compost

Results_ ARGs

‐350% ‐250% ‐150% ‐50% 50% 150% Aeration‐0.25 Aeration‐0.1 Aeration‐0.05 Turn Static Aeration‐0.25 Aeration‐0.1 Aeration‐0.05 Turn Static

Removal rate of each ARG

blaTEM ermB qnrS tetH tetO tetW sulI sulII intI Day 21/Thermophilic phase Day 77/Maturity phase

Results_ ARGs

The heatmap of ARGs variation pattern during the whole composting process among 5 different aeration methods. Data were analyzed based on the ratio of absolute quantities of ARGs and 16S rRNA gene

Results_ Microbial community

Phylum level Genus level

Results_ Network analysis

A connection represents a significant positive correlation (P < 0.05) according to Spearman’s rank

• analysis. The blue and red lines

were designated with negative and positive correlations, respectively.

Network analysis based on the co-occurrence of representative ARGs and their potential host bacteria.

Conclusion

 Composting was an efficient tool in terms of reducing most of ARGs in original swine manure, but sulfonamide resistance gene (sulI/sulII) and integrase gene (intI) were enriched instead of removal.  The aeration methods showed little influence on the variation patterns of ARGs, especially the intractable stubborn ARGs like sulI/sulII/intI, innovative methods should be further developed for the elimination of these genes in compost.  The enrichment of sulI/sulII/intI at the end of the composting was correlated with the increase of genera belonged to Actinobacteria, Proteobacteria and Bacteroidetes and the decrease of genera affiliated with Firmicutes.

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