Intramuscular therapeutic doses of enrofloxacin affect microbial community structure but not the relative abundance of fluoroquinolones resistance genes in swine manure.

Livestock manure is a major source of veterinary antibiotics and antibiotic resistance genes (ARGs). Elucidation of the residual characteristics of ARGs in livestock manure following the administration of veterinary antibiotics is critical to assess their ecotoxicological effects and environmental contamination risks. Here, we investigated the effects of enrofloxacin (ENR), a fluoroquinolone antibiotic commonly used as a therapeutic drug in animal husbandry, on the characteristics of ARGs, mobile genetic elements, and microbial community structure in swine manure following its intramuscular administration for 3 days and a withdrawal period of 10 days. The results revealed the highest concentrations of ENR and ciprofloxacin (CIP) in swine manure at the end of the administration period, ENR concentrations in swine manure in groups L and H were 88.67 ± 45.46 and 219.75 ± 88.05 mg/kg DM, respectively. Approximately 15 fluoroquinolone resistance genes (FRGs) and 48 fluoroquinolone-related multidrug resistance genes (F-MRGs) were detected in swine manure; the relative abundance of the F-MRGs was considerably higher than that of the FRGs. On day 3, the relative abundance of qacA was significantly higher in group H than in group CK, and no significant differences in the relative abundance of other FRGs, F-MRGs, or MGEs were observed between the three groups on day 3 and day 13. The microbial community structure in swine manure was significantly altered on day 3, and the altered community structure was restored on day 13. The FRGs and F-MRGs with the highest relative abundance were qacA and adeF, respectively, and Clostridium and Lactobacillus were the dominant bacterial genera carrying these genes in swine manure. In summary, a single treatment of intramuscular ENR transiently increased antibiotic concentrations and altered the microbial community structure in swine manure; however, this treatment did not significantly affect the abundance of FRGs and F-MRGs.

Chinese Herbal Extracts Mitigate Ammonia Generation in the Cecum of Laying Hens: An In Vitro Study.

The objectives of the study were to screen one or several Chinese herbal extracts with good ammonia emission reduction effects using an in vitro gas production study. The study consisted of a control (without Chinese herbal extract), and 11 experimental groups with added cinnamon extract (CE), Osmanthus extract (OE), tangerine peel extract (TPE), dandelion extract (DE), Coptis chinensis extract (CCE), honeysuckle extract (HE), Pulsatilla root extract (PRE), yucca extract (YE), licorice extract (LE), Ginkgo biloba extract (GBE), or astragalus extract (AE). The results showed that HE, PRE, YE, LE, GBE, and AE significantly reduced ammonia production (p ≤ 0.05). The most significant ammonia inhibition was achieved via AE, resulting in a 26.76% reduction. In all treatments, Chinese herbal extracts had no significant effect on pH, conductivity, or uric acid, urea, and nitrate-nitrogen concentrations (p > 0.05). However, AE significantly reduced urease activity and the relative activity of uricase (p ≤ 0.05). AE significantly increased the relative abundance of Bacteroides and decreased the relative abundance of Clostridium, Desulfovibrio, and Prevotell (p ≤ 0.05). Astragalus extract inhibited ammonia emission from laying hens by changing the gut microbial community structure, reducing the relative abundance of ammonia-producing bacteria, and reducing microorganisms' uricase and urease activities.

Sodium butyrate reduces ammonia emissions through glutamate metabolic pathways in cecal microorganisms of laying hens.

Ammonia emission is an important problem that needs to be solved in laying hen industries. Sodium butyrate (SB) is considered to have potential for reducing ammonia production because of its ability to improve nitrogen metabolism. In this in vitro fermentation study, we presented a correlation analysis of the metatranscriptome and metaproteome of lay hen cecal microorganisms, in order to identify important proteins and pathways involved in ammonia production reduction due to sodium butyrate supplementation. The results showed that sodium butyrate supplement decreased the production of ammonia by 26.22% as compared with the non-sodium butyrate supplementation (CK) group. The SB group exhibited a lower concentration of ammonium nitrogen (NH4+-N) and a decreased pH. Sodium butyrate promoted the uric acid concentration and lowered the uricase activity in the fermentation broth of laying hens cecal content. Notably, the 'alanine, aspartate and glutamate metabolism' category was more abundant in the SB group. The addition of sodium butyrate increased the expression of glutamate dehydrogenase (GDH) gene in cecal microbiota (e.g., Ruminococcus sp. and Bacteroides sp.) in vitro. The metaproteome analysis results showed that the expression of GDH with NADPH as coenzyme (NADPH-GDH) was up-regulated in cecal microbiota by sodium butyrate supplement. Our results indicate that sodium butyrate can affect glutamate metabolism through regulating the expression of glutamate dehydrogenase in cecal microorganisms, thereby reducing ammonia production. This study reveals that glutamate dehydrogenase-mediated glutamate metabolism play a key role in ammonia emission reduction in laying hen and provide theoretical basis for further developing ammonia production reduction approach.

[Comparison of nutrient removal ability between Cyperus alternifolius and Vetiveria zizanioides in constructed wetlands].

In order to compare the nutrient removal ability of Cyperus alternifolius and Vetiveria zizanioides, a 17.0 m2 subsurface flow wetland covered with Cyperus alternifolius and another 13.3 m2 one covered with Vetiveria zizanioides were constructed for piggery wastewater treatment, and the biomass as well as the N, P, Cu and Zn contents in the root and shoot of the plants was measured by the end of each season. The results showed that the below-ground biomass of V. zizanioides was greater than that of C. alternifolius. By the contrary, the above-ground biomass of C. alternifolius was greater than that of V. zizanioides. The annual biomass yield of C. alternifolius was 2.3 times higher than that of V. zizanioides,which was 3406.47 g x m(-2) and 1483.88 g x m(-2), respectively. The N concentration in C. alternifolius tissue was higher than that in V. zizanioides tissue, being 22.69 mg x g(-1) and 15.44 mg x g(-1) respectively, and similarly, the P concentration in C. alternifolius tissue was higher than that in V. zizanioides tissue, being 6.09 mg x g(-1) and 5.47 mg x g(-1) respectively. The Cu and Zn concentrations in C. alternifolius tissue were a little higher than those in V. zizanioides. 68.72 g N x m(-2) and 18.49 g P x m(-2) were removed by harvesting C. alternifolius vegetation, while 8.93 g N x m(-2) and 3.69 g x P m(-2) were removed by harvesting V. zizanioides vegetation. It was concluded that the removals of N, P, Cu and Zn by harvesting vegetation were 4-7 times higher in C. alternifolius wetland than in V. zizanioides wetland.