Responses of Enterococcus faecalis resistance and cytolysin up-regulation to nutrients in constructed mesocosms

Ali, Liaqat; Mustafa, Muhammad; Xiao, Zheng; Islam, Waqar; Ara, Ulfat; Ajmal, Muhammad; Khan, Khalid Ali; Ghramh, Hamed A.; Yu, Daojin

doi:10.1016/j.jksus.2021.101680

Cited by 1 publication

(1 citation statement)

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“…Although Enterococcus species do not produce spores, their relative resistance could be due to the presence of a thick layer of peptidoglycan and teichoic acids that selectively prevent toxic substances from entering the cell. Furthermore, their ability to produce biofilms could enhance their resistance to disinfection [ 43 ]. These results further demonstrate that residence time alone would not play a significant role in eliminating resistant species in AD effluent.…”

Section: Discussionmentioning

confidence: 99%

Effect of the Inoculum-to-Substrate Ratio on Putative Pathogens and Microbial Kinetics during the Batch Anaerobic Digestion of Simulated Food Waste

Otite,

Gandhi,

Agyabeng Fofie

et al. 2024

Microorganisms

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The effects of the inoculum (anaerobic digestion effluent) to substrate (simulated food waste) ratio (ISR) 4.00 to 0.25 on putative pathogens and microbial kinetics during batch mesophilic anaerobic digestion were investigated. Red fluorescent protein labelled (RFPAKN132) Escherichia coli JM105 was introduced as a marker species, and together with the indigenous Clostridium sp., Enterococcus sp., Escherichia coli, and total coliforms were used to monitor pathogen death kinetics. Quantitative polymerase chain reaction was also used to estimate the bacterial, fungal, and methanogenic gene copies. All the ISRs eliminated E. coli and other coliforms (4 log10 CFU/mL), but ISR 0.25 achieved this within the shortest time (≤2 days), while ISR 1.00 initially supported pathogen proliferation. Up to 1.5 log10 CFU/mL of Clostridium was reduced by acidogenic conditions (ISR 0.25 and 0.50), while Enterococcus species were resistant to the digestion conditions. Fungal DNA was reduced (≥5 log10 copies/mL) and was undetectable in ISRs 4.00, 2.00, and 0.50 at the end of the incubation period. This study has demonstrated that ISR influenced the pH of the digesters during batch mesophilic anaerobic digestion, and that acidic and alkaline conditions achieved by the lower (0.50 and 0.25) and higher (4.00 and 2.00) ISRs, respectively, were critical to the sanitisation of waste.

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Section: Discussionmentioning

confidence: 99%