Composting increased persistence of manure-borne antibiotic resistance genes in soils with different fertilization history

Microbiological safety and antibiotic resistance risks at a sustainable farm under large-scale open-air composting and composting toilet systems

“…In recent years, the problem of antibiotic resistance [1][2][3] has become a major public health crisis [4][5][6][7][8][9] and has triggered a sharp increase in medical costs and mortality worldwide [2][3][4][5][8][9][10][11][12][13][14][15][16]. Such resistance is induced by the abuse of antibiotics in the prevention and treatment of human and animal diseases and growth promotion in livestock [12,13,15,[17][18][19][20][21][22][23]. It is estimated that the annual global use of antibiotics is between 100,000 and 200,000 tons [18], of which the consumption of antibiotics increased by about 69% from 2000 to 2015, an increase of more than 4% per year [19].…”

“…With the continuous pursuit of ecological environmental protection and organic food intake [11], use of human and animal waste in composting and subsequent land application has become a routine procedure [26] which will enrich antibiotic resistance [4,32,33]. However, due to the abuse of antibiotics and their incomplete metabolism [18,24], abundant residues of antibiotics, ARB, ARGs and mobile genetic elements (MGEs) in human and animal feces [4,22,23,32] are consistently released into the environment, thus seriously threatening the ecological environment and human health [4,18,26,32,33]. In recent years, aerobic composting has been widely used as an effective bioremediation technology [18,34,35] in utilising manure as a harmless source for soil improvement [12,14,22,28,34].…”

“…However, due to the abuse of antibiotics and their incomplete metabolism [18,24], abundant residues of antibiotics, ARB, ARGs and mobile genetic elements (MGEs) in human and animal feces [4,22,23,32] are consistently released into the environment, thus seriously threatening the ecological environment and human health [4,18,26,32,33]. In recent years, aerobic composting has been widely used as an effective bioremediation technology [18,34,35] in utilising manure as a harmless source for soil improvement [12,14,22,28,34]. Yet, numerous studies have reported significant differences in the removal effect of different antibiotics and resistance to them, which may further enhance the migration and spread of AMR [12,18,22,28].…”

“…In recent years, aerobic composting has been widely used as an effective bioremediation technology [18,34,35] in utilising manure as a harmless source for soil improvement [12,14,22,28,34]. Yet, numerous studies have reported significant differences in the removal effect of different antibiotics and resistance to them, which may further enhance the migration and spread of AMR [12,18,22,28]. In addition, to better ensure food security and human health, the number of human pathogens in manure compost should be reduced to avoid pathogen contamination of crops [28].…”

“…Studies have shown that antibiotics, animal-derived bacteria, and their ARGs remain in manure and compost is introduced into the receiving soil with land application, which gradually migrate and spread into deeper soil layers and/or groundwater [4,11,17,23]. This transfer subsequently influences the overall microbial community structure and soil activity, inducing the formation and development of antibiotic resistance in the bacterial community through selection pressure [7,11,22,26,30,32,36], prompting the soil to become a reservoir for ARBs [4,7,30]. Furthermore, ARBs and their genomes from soil or irrigation water can enter the food chain through contaminated plant-derived foods, especially produce that is typically eaten raw, posing a serious threat to animal and human health [5,11,21,23,26,28,30].…”