Temperature affects variations of class 1 integron during sludge anaerobic digestion

Zhang, Yan; Su, Yu-ao; Qiu, Xuyang; Mao, Qiuyan; Liu, Hongbo; Li, He; Wen, Donghui; Su, Zhiguo

doi:10.1016/j.biortech.2022.128005

Cited by 8 publications

(3 citation statements)

References 38 publications

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“…This finding agrees with our proposed hypothesis of decreased intI 1 gene abundance as a result of increased temperature driving enhanced wastewater treatment. Although the target internal temperature (50°C–60°C) within the solar tank was not consistently achieved, our finding is consistent with the recent study by Zhang and colleagues ( 53 ), who investigated removal of CL1-integron and entrained AMR genes from anaerobic digestors operated at higher (thermophilic: 55°C) and lower (mesophilic: 35°C and 25°C) temperatures and reported statistically lower intI 1 gene abundance and removal at higher temperature. In addition, statistically lower 16S rRNA gene abundance was reported at the higher temperature, coupled with a lower relative abundance of AMR gene cassettes, albeit slightly higher ARG subtypes were detected with the higher temperature.…”

Section: Discussionsupporting

confidence: 92%

intI 1 gene abundance from septic tanks in Thailand using validated intI 1 primers

Okonkwo,

Cholet,

Ijaz

et al. 2023

Appl Environ Microbiol

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Antimicrobial resistance (AMR) poses a serious global health threat, and wastewater treatment (WWT), including septic tanks, is a source of AMR. In Thailand, antibiotics are unregulated, and septic tanks are commonly used. Yet, their impact on the spread or mitigation of AMR is unknown. We monitored household and healthcare conventional septic tanks (CST) and household solar septic tanks (SST) in Thailand using the class 1 integron-integrase ( intI 1) gene abundance as a proxy for AMR. A systematic review of the literature found 65 intI 1 primers. We evaluated the coverage and specificity of each, including a new MGB TaqMan primer-probe, against clinical and environmental intI 1, intI 1-like, and non- intI 1 databases. The three best primers were selected, laboratory validated for DNA and mRNA quantification, and used to quantify septic tank intI 1 gene abundance. No primer set could distinguish between intI 1 and intI 1-like sequences. While primer choice did not affect gene abundance of the same sample ( P -value > 0.05), sometimes when comparing the same samples quantified by different primers, statistical differences were observed for one but not the other primer set. This may lead to different interpretations of AMR risk. Irrespective of primers or reactor type intI 1 gene abundance was greatest in influent > effluent > sludge. intI 1 gene abundance was lowest in the effluent of the SST-household < CST-household < CST-healthcare. 31% to 42% of intI 1 was removed by the CST-household tank, indicating while septic tanks remove some intI 1 they remain a source to the surrounding environment. Toward the goal of achieving standardization across studies, we recommend the F3-R3 primer for intI 1 quantification. IMPORTANCE Antimicrobial resistance is a global crisis, and wastewater treatment, including septic tanks, remains an important source of antimicrobial resistance (AMR) genes. The role of septic tanks in disseminating class 1 integron, and by extension AMR genes, in Thailand, where antibiotic use is unregulated remains understudied. We aimed to monitor gene abundance as a proxy to infer potential AMR from septic tanks in Thailand. We evaluated published intI 1 primers due to the lack of consensus on optimal Q-PCR primers and the absence of standardization. Our findings confirmed septic tanks are a source of class 1 integron to the environment. We highlighted the significance of intI 1 primer choice, in the context of interpretation of risk associated with AMR spread from septic tanks. We recommend the validated set (F3-R3) for optimal intI 1 quantification toward the goal of achieving standardization across studies.

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Section: Discussionsupporting

confidence: 92%

intI 1 gene abundance from septic tanks in Thailand using validated intI 1 primers

Okonkwo,

Cholet,

Ijaz

et al. 2023

Appl Environ Microbiol

View full text Add to dashboard Cite

show abstract

“…This finding agrees with our proposed hypothesis of decreased intl1 gene abundance as a result of increased temperature driving enhanced wastewater treatment. Although the target internal temperature (50-60°C) within the solar tank was not consistently achieved, our finding is consistent with the recent study by Zhang and colleagues (Zhang et al, 2022), who investigated removal of CL1-integron and entrained AMR genes from anaerobic digestors operated at higher (thermophilic-55°C) and lower (mesophilic-35°C and 25°C) temperatures and reported statistically lower intI1 gene abundance and removal at higher temperature. In addition, statistically lower 16S rRNA gene abundance was reported at the higher temperature, coupled with a lower relative abundance of AMR gene cassettes, albeit slightly higher ARG subtypes was detected with the higher temperature.…”

Section: Ecological Risk Assessment Of Septic Tanks In Contributing T...supporting

confidence: 92%

intI1 primer selection for class 1 integron integrase gene and transcript quantification – validation and application for monitoringintl1 gene abundance within septic tanks in Thailand

Okonkwo,

Cholet,

Ijaz

et al. 2023

Preprint

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Antimicrobial resistance (AMR) poses serious global public health threat and wastewater treatment (WWT), including septic tanks, are a significant source of AMR genes to the environment. Environmental monitoring of broad-range AMR genes remains a challenge. The class-1 integron-integrase (intI1) gene has been proposed as a proxy for overall AMR abundance, but there is no consensus on the qPCR primer set to use. A systematic review of the literature found 65 primer sets. The coverage and specificity of each, including newly designed MGB-TaqMan primer-probe, was evaluated against a database of clinical and environmental intl1, intl1-like and non-intl1 sequences. Three primer sets were selected, laboratory validated for DNA and mRNA quantification and used to quantity intl1 gene abundance from household and healthcare conventional septic tanks (CST) and novel household Solar Septic Tanks (SST) in Thailand. Specificity of the intl1 septic tank amplicons showed that no primer set could distinguish between intl1 and intl-1 like sequences. Each primer set showed the same trends across septic tanks, with highest gene abundance in influent>sludge>effluent. There was no statistical difference between the same sample quantified by the three primer sets. However, when comparing gene abundances from the same primer set across septic tanks, statistical differences between different sample types were observed for one primer set but not the others. This may lead to different interpretation of risk associated with each reactor in spreading intl1 to the environment. Comparing reactor types, intI1 abundance in the effluent was lowest in the SST-household<CST-household<CST-healthcare. Depending on primer set used, 31 to 42% of intI1 was removed from effluent of the CST-household tank with accessible influent. Our study provided insight into the importance of intl1 primer choice. We propose the use of the validated set (F3-R3) for optimal intI1 quantification and towards the goal of achieving standardisation across environmental studies.

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“…Several gene cassettes are associated with class 1 integrons in bacteria that contain MPs compared to bacteria that do not. 76 Sludge anaerobic digestion increases the antimicrobial resistance genes. It promotes the spread of antimicrobial resistance genes through mobile gene genetic elements at a concentration of 10 mg L −1 , which is a hundredfold higher environmental concentration of dimethyl phthalate in the water.…”

Section: Mps In the Dissemination Of Antibiotic Resistancementioning

confidence: 99%

Microplastic emerging pollutants – impact on microbiological diversity, diarrhea, antibiotic resistance, and bioremediation

Uthra,

Chitra,

Damodharan

et al. 2023

Environ. Sci.: Adv.

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Temperature affects variations of class 1 integron during sludge anaerobic digestion

Cited by 8 publications

References 38 publications

intI 1 gene abundance from septic tanks in Thailand using validated intI 1 primers

intI 1 gene abundance from septic tanks in Thailand using validated intI 1 primers

intI1 primer selection for class 1 integron integrase gene and transcript quantification – validation and application for monitoringintl1 gene abundance within septic tanks in Thailand

Microplastic emerging pollutants – impact on microbiological diversity, diarrhea, antibiotic resistance, and bioremediation

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