Response of microbial communities to roxarsone under different culture conditions

Abstract

Roxarsone is a feed additive widely used in the broiler and swine industries that has the potential to contaminate the environment, mainly via the use of poultry manure as fertilizer, which results in release of inorganic arsenic to the soil and water. This study was conducted to investigate roxarsone degradation and the response of the microbial community under different culture conditions using high-throughput sequencing technology. Poultry litter was incubated for 288 h in the presence of roxarsone under light aerobic, dark aerobic, or dark anaerobic conditions. The results showed that roxarsone was completely degraded after 48 h of dark anaerobic incubation, while 79.9% and 94.5% of roxarsone was degraded after 288 h of dark aerobic and light aerobic incubation, respectively. Under dark aerobic conditions with microbial inhibitor sodium azide, roxarsone was rarely degraded during the 288 h of incubation, illustrating that microorganisms play an important role in roxarsone degradation. Microbial community structure was significantly different among various culture conditions. Olivibacter, Sphingobacterium, and Proteiniphilum were the top 3 genera in the control samples. Sphingobacterium and Alishewanella dominated the light aerobic samples, while the dominant microflora of the dark aerobic samples were Acinetobacter spp. Pseudomonas and Advenella were the predominant genera of dark anaerobic samples. This study emphasizes the potential importance of microbes in roxarsone degradation and expands our current understanding of microbial ecology during roxarsone degradation under different environmental conditions.

Identification of an anaerobic bacterial consortium that degrades roxarsone

“…nov. strain OhILAs is capable of transforming ROX (Fisher et al, 2008). In previous studies, Alkaliphilus was shown to be closely correlated with the presence of arsenic and ROX (Liu, Zhang, Li, & Fei, 2017b), which aligns with our own results…”

“…nov. strain OhILAs is capable of transforming ROX (Fisher et al, ). In previous studies, Alkaliphilus was shown to be closely correlated with the presence of arsenic and ROX (Liu, Zhang, Li, & Fei, ), which aligns with our own results showing Alkaliphilus to be the predominant genus of the bacterial community that degraded ROX. However, to our knowledge, we are the first to report the relationship between Proteiniclasticum and arsenic, although further studies are needed to reveal the function of Proteiniclasticum in arsenic transformation.…”

“…The results of ROX biodegradation at different concentrations illustrated that anaerobic microbes possess great potential for this process. Similar results were obtained in a study of ROX degradation at different ROX concentrations (0, 50, 100, and 200 mg/kg) in soil, and it was found that the degradation rate increased with increasing concentrations, further highlighting the considerable potential of soil microbes to degrade ROX (Liu, Zhang, Li, & Fei, 2017b). The presence of ROX promoted microbial growth, and in turn, the microorganisms degraded ROX.…”

“…There have been some previous reports on the relationship between Firmicutes and ROX. Firmicutes represents the most abundant phylum in soils treated with ROX, with its abundance increasing as ROX concentrations increase, implying that Firmicutes abundance might be related either directly to ROX or to arsenic compounds released during its degradation (Liu, Zhang, Li, & Fei, 2017b). Similarly, Firmicutes were the predominant group in a microbial consortium that degraded ROX (Guzmán-Fierro et al, 2015).…”

Public Health Risk of Arsenic Species in Chicken Tissues from Live Poultry Markets of Guangdong Province, China

“…A nationwide survey of animal feeds conducted in 2012 found that the feed products from 34 manufacturers did not meet the safety requirements, and around half of them contained arsenic exceeding the allowable limit . The inorganic arsenic might also result from degradation of ROX in the feeds during storage and handling, as a variety of microbes are capable of degrading ROX, − although the actual contribution of this deserves further investigation.…”