徐俊 侯玉潔 謝敏 王夢(mèng)芝 鄔磊 費(fèi)丹 周瑤敏 胡麗芳
徐俊(1986-),博士,主要從事動(dòng)物營養(yǎng)與質(zhì)量安全風(fēng)險(xiǎn)評(píng)估研究工作。先后主持國家自然科學(xué)基金項(xiàng)目、江西省重點(diǎn)研發(fā)計(jì)劃項(xiàng)目及江西省協(xié)同創(chuàng)新項(xiàng)目等國家級(jí)或省部級(jí)科研項(xiàng)目6項(xiàng);作為主要成員參與國家自然科學(xué)基金項(xiàng)目、國家科技支撐計(jì)劃項(xiàng)目及農(nóng)業(yè)農(nóng)村部農(nóng)產(chǎn)品質(zhì)量安全風(fēng)險(xiǎn)評(píng)估等科研項(xiàng)目10余項(xiàng)。獲江西省科技進(jìn)步獎(jiǎng)一等獎(jiǎng)1項(xiàng),農(nóng)業(yè)農(nóng)村部農(nóng)產(chǎn)品質(zhì)量安全中心科普獎(jiǎng)2項(xiàng);制定地方標(biāo)準(zhǔn)6項(xiàng);獲授權(quán)國家發(fā)明專利3項(xiàng)、實(shí)用新型專利5項(xiàng);獲軟件著作權(quán)3項(xiàng);參編著作5部;在《Journal of Integrative Agriculture》《Asian-Australasian Journal of Animal Sciences》《Frontiers in Microbiology》《動(dòng)物營養(yǎng)學(xué)報(bào)》《南方農(nóng)業(yè)學(xué)報(bào)》《分析試驗(yàn)室》等科技期刊上發(fā)表學(xué)術(shù)論文20余篇。
摘要:【目的】探討矮腳黃雞口服利巴韋林后其腸道微生物群落結(jié)構(gòu)多樣性的變化情況,揭示抗病毒藥物對(duì)動(dòng)物腸道健康的影響機(jī)制,為科學(xué)禁用抗生素及開發(fā)綠色生態(tài)飼料提供理論依據(jù)?!痉椒ā?0日齡矮腳黃雞按10 mg/kg的劑量連續(xù)口服利巴韋林溶液7 d(試驗(yàn)組),以口服等量生理鹽水為對(duì)照組,停藥后收集4 h內(nèi)的新鮮雞糞。通過糞便基因組提取試劑盒提取雞糞總DNA,根據(jù)細(xì)菌16S rDNA序列V3~V4可變區(qū),設(shè)計(jì)通用引物338F和806R進(jìn)行PCR擴(kuò)增,然后參照Illumina MiSeq平臺(tái)上機(jī)說明進(jìn)行Illumina MiSeq高通量測(cè)序。【結(jié)果】從16個(gè)矮腳黃雞糞便樣品中共獲得614626條原始序列(Raw reads),經(jīng)質(zhì)量控制后獲得606862條優(yōu)質(zhì)序列(Clean reads),按97%的序列相似度進(jìn)行OTU聚類分析獲得968個(gè)OTUs,對(duì)照組和試驗(yàn)組共享624個(gè)OTUs。矮腳黃雞腸道微生物群落豐富度指數(shù)(Chao1和ACE)表現(xiàn)為對(duì)照組顯著(P<0.05,下同)或極顯著(P<0.01,下同)高于試驗(yàn)組;在物種多樣性方面,Simpson指數(shù)的組間差異不顯著(P>0.05),Shannon指數(shù)則表現(xiàn)為試驗(yàn)組顯著高于對(duì)照組。對(duì)照組和試驗(yàn)組的矮腳黃雞糞便樣品均以厚壁菌門、放線菌門、擬桿菌門和變形菌門為優(yōu)勢(shì)菌門,相對(duì)豐度均在5.00%以上;在屬分類水平上,相對(duì)豐度大于0.10%的屬共有108個(gè),對(duì)照組和試驗(yàn)組均以乳桿菌屬相對(duì)豐度最高,分別為34.07%和19.26%。矮腳黃雞口服利巴韋林后,腸道中的乳桿菌屬、腸球菌屬、Paeniglutamicibacter、Tessaracoccus、埃希氏桿菌屬、副球菌屬、Gottschalkia及黃桿菌屬呈顯著或極顯著下降趨勢(shì),而擬桿菌屬、葡萄球菌屬、疊球菌屬、Jeotgalicoccus、Unclassified_f_rikenellaceae、Unclassifier_o_bacteroidales、Rikenellaceae_RC9_gut_group、明串珠菌屬及丹毒絲菌屬呈顯著或極顯著上升趨勢(shì)。UniFrac-PCoA分析發(fā)現(xiàn),第一主成分(PC1)和第二主成分(PC2)的貢獻(xiàn)率分別為73.44%和6.99%,對(duì)照組和試驗(yàn)組間的微生物群落結(jié)構(gòu)差異明顯,彼此間可較好地區(qū)分開,但同處理組內(nèi)的8個(gè)樣品能很好地聚在一起,菌群相似度很高?!窘Y(jié)論】口服利巴韋林會(huì)顯著影響矮腳黃雞腸道微生物區(qū)系,改變腸道微生物的穩(wěn)態(tài)結(jié)構(gòu),進(jìn)而導(dǎo)致其腸道健康受到損傷。
關(guān)鍵詞: 矮腳黃雞;利巴韋林;腸道微生物;豐富度;多樣性;Illumina MiSeq高通量測(cè)序
中圖分類號(hào): S831.92? ? ? ? ? ? ? ? ? ? ? ? ? 文獻(xiàn)標(biāo)志碼: A 文章編號(hào):2095-1191(2021)05-1139-10
Abstract:【Objective】The structural diversity of the intestinal microbiological community in dwarf yellow chicken after oral ribavirin was discussed, the mechanism of the effects of antiviral drugs on animal intestinal health was revealed, and provided theoretical basis for scientific prohibition on the addition of antibiotics and the development of green ecological feed. 【Method】Dwarf yellow chicken at 90 d were selected as experimental animal, and took ribavirin orally for 7 consecutive d according to the body weight dose of 10 mg/kg (treatment group), the same amount of normal saline was taken orally as control group. Manure samples were collected within 4 h after the drug stopped.The total chicken manure DNA was extracted from the fecal genome extraction kit, according to bacterial 16S rDNA sequence V3-V4 variable region, common primers 338F and 806R were designed for PCR amplification, then conducted Illumina MiSeq high-throughput sequencing with reference to the on-board Illumina MiSeq platform instructions. 【Result】In total, 614626 raw reads were obtained for the bacterial 16S rRNA genes analysis. After screening these gene sequences with strict criteria, 606862 clean reads were obtained. OTU cluster analysis based on 97% sequence similarity obtained 968 OTUs. Additional-ly, there were 624 OTUs shared between the groups. The intestinal microbiological community richness indexes(Chao1 and ACE) in the control group were significant(P<0.05, the same below) or extremely significant(P<0.01, the same below)? higher than in the treatment group. In species diversity, the Simpson index was not significant between groups(P>0.05),? Shannon index in control group was significantly higher compared to treatment group. At the phylum level, Firmicutes, Actinobacteria, Bacteroidetes and Proteobacteria were the dominant phyla in both groups, with average relative abundance above 5.00%. At the genus level, there were 108 genera accounted for more than 0.10% relative abundance, and Lactobacillus accounted for the highest relative abundance in the control group and the treatment group, which were 34.07% and 19.26% respectively. After oral administration of ribavirin, Lactobacillus, Enterococcus, Paeniglutamicibacter, Tessaracoccus, Escherichia, Paracoccus, Gottschalkia and Flavobacterium significantly or extremely decreased, while Bacteroides, Staphylococcus, Methylosarcina, Jeotgalicoccus、Unclassified_f_rikenellaceae、Unclassifier_o_bacteroidales、Rikenellaceae_RC9_gut_group, Leuconostoc and Erysipelothrix significantly or extremely increased. The UniFrac-PCoA weighted principal coordinate analysis found that the primary component(PC1) and secondary component (PC2) contributed 73.44% and 6.99%, respectively. The microbial community structure difference between the control group and the treatment group was obvious, which could be better separated from each other, but the 8 samples in the treatment group could be well gathered together, and the flora similarity was very high. 【Conclusion】Oral administration of ribavirin can significantly affect the intestinal microflora of dwarf yellow chicken, and change the steady-state structure of the intestinal microorganisms, which can cause the impaired of the intestinal health.
Key words: dwarf yellow chicken; ribavirin; intestinal microflora; richness; diversity; Illumina MiSeq high throughput sequencing
Foundation item:Key Research and Development Project of Jiangxi(20192ACB60004); Postdoctoral Research Fund of Jiangxi(2015KY43)
0 引言
【研究意義】動(dòng)物消化道內(nèi)的微生物不僅有助于營養(yǎng)攝取、免疫調(diào)節(jié)及消化道上皮細(xì)胞的發(fā)育,還是抵御病原體的天然屏障,對(duì)維持宿主健康至關(guān)重要(Zoetenal et al.,2004;曾波等,2017)。促生長類抗生素在促進(jìn)動(dòng)物生長(Emami et al.,2012)的同時(shí)會(huì)導(dǎo)致動(dòng)物腸道微生物群落結(jié)構(gòu)多樣性及其穩(wěn)態(tài)發(fā)生改變(Vangay et al.,2015;辛可啟等,2020),盡管抗生素的使用主要針對(duì)致病菌,但對(duì)整個(gè)腸道菌群也會(huì)產(chǎn)生重要影響(Jernberg et al.,2010;Looft et al.,2014)。因此,研究抗生素對(duì)動(dòng)物胃腸道微生物群落結(jié)構(gòu)的影響,對(duì)深入探究動(dòng)物消化道微生物穩(wěn)態(tài)機(jī)理具有重要意義?!厩叭搜芯窟M(jìn)展】已有研究證實(shí),抗生素可通過亞治療劑量促進(jìn)動(dòng)物機(jī)體生長,究其原因主要是抗生素能控制胃腸道感染及調(diào)控腸道微生物群落結(jié)構(gòu)(Dibner and Richards,2005;Torok et al.,2011),雖然其作用機(jī)制尚未明確,但可確認(rèn)抗生素是通過重塑腸道微生物多樣性及其相對(duì)豐度而發(fā)揮作用,為動(dòng)物機(jī)體的生長營造最佳微生態(tài)環(huán)境(郭鵬等,2017;王歡等,2020)。Dumonceaux等(2006)以維吉尼亞霉素為肉雞生長促進(jìn)劑添加至飼料中,結(jié)果發(fā)現(xiàn)雛雞回腸近端及十二指腸中乳酸桿菌的種類有所增加,即在飼料中添加維吉尼亞霉素會(huì)改變?nèi)怆u近端胃腸道的菌群結(jié)構(gòu)。但也有研究報(bào)道,在家禽養(yǎng)殖過程中使用抗生素會(huì)導(dǎo)致乳酸桿菌的種類減少,且雞腸道菌群結(jié)構(gòu)的變化還會(huì)影響其免疫功能和健康狀況(謝全喜等,2012;Lee et al.,2012)。La-ongkhum等(2011)采用PCR-DGGE研究阿維菌素對(duì)肉仔雞空腸內(nèi)微生物菌群的影響,發(fā)現(xiàn)阿維菌素可改變腸道中魏斯氏菌屬、糞鏈球菌和嗜酸乳桿菌的含量,降低腸道內(nèi)微生物菌群多樣性。倪江(2013)研究發(fā)現(xiàn),在嶺南黃肉雞的基礎(chǔ)日糧中分別添加林可霉素、桿菌肽鋅和硫酸粘桿菌素,各處理組肉雞腸道中大腸桿菌、乳酸桿菌及雙歧桿菌的數(shù)量有升有降,而肉雞日增重分別提高5.86%、5.31%和3.73%,故推測(cè)抗生素對(duì)腸道微生物的影響只是抗生素促生長機(jī)理的一部分。Elokil等(2020)研究表明,給京紅雞口服恩諾沙星和地克珠利后其腸道中的微生物組成發(fā)生顯著變化,且停藥后無法恢復(fù)到原腸道微生態(tài)結(jié)構(gòu)。針對(duì)豬的研究發(fā)現(xiàn),飼喂抗生素會(huì)促使其回腸中的厚壁菌門和放線菌門相對(duì)豐度降低,變形菌門相對(duì)豐度提高,回腸和糞便中的有益菌屬下降,而有害的條件性致病菌相對(duì)豐度增加(高侃等,2016)。Zhang等(2016)研究表明,給斷奶仔豬口服乳酸菌或金霉素后,其空腸、結(jié)腸和盲腸的微生物多樣性及組成均不相同,以金霉素組的厚壁菌門和普氏菌屬相對(duì)豐度更高。Li等(2020)針對(duì)長期使用抗生素的豬腸道微生物群落多樣性進(jìn)行分析,結(jié)果發(fā)現(xiàn)厚壁菌門和擬桿菌門(F/B)比值隨著育肥時(shí)間的推移而顯著增加,且變形菌門和纖維桿菌門的相對(duì)豐度顯著低于無抗生素組。目前,除了研究在飼料中添加抗生素對(duì)動(dòng)物腸道微生物群落結(jié)構(gòu)的影響外,還有關(guān)于注射抗生素對(duì)其影響的相關(guān)研究(Janczyk et al.,2007;Fleury et al.,2015)。Ruczizka等(2020)在評(píng)估注射頭孢噻肟對(duì)哺乳仔豬和生長豬糞便微生物群落結(jié)構(gòu)的影響時(shí)發(fā)現(xiàn),產(chǎn)后12 h注射頭孢噻肟會(huì)顯著影響雌、雄性仔豬糞便微生物組成的連續(xù)變化,同時(shí)對(duì)宿主生產(chǎn)性能造成長期影響?!颈狙芯壳腥朦c(diǎn)】至今,有關(guān)抗生素對(duì)動(dòng)物腸道微生物影響的研究主要集中在飼用抗生素方面(倪江和楊維仁,2012;劉穎等,2017;于佳民等,2018),而有關(guān)抗病毒藥物對(duì)動(dòng)物腸道微生物群落結(jié)構(gòu)影響的研究鮮見報(bào)道。在家禽的養(yǎng)殖過程中,養(yǎng)殖戶為降低病毒性疾病帶來的養(yǎng)殖風(fēng)險(xiǎn),經(jīng)常性使用違禁抗病毒藥物(目前尚未批準(zhǔn)的獸用抗病毒藥物)預(yù)防或治療病毒性疾病,尤其是近幾年的風(fēng)險(xiǎn)評(píng)估發(fā)現(xiàn)違規(guī)使用利巴韋林現(xiàn)象仍較普遍,是影響家禽產(chǎn)品質(zhì)量安全的主要因素之一。【擬解決的關(guān)鍵問題】通過Illumina MiSeq高通量測(cè)序技術(shù)探討矮腳黃雞口服利巴韋林后其腸道微生物群落結(jié)構(gòu)多樣性的變化情況,進(jìn)一步揭示抗病毒藥物對(duì)動(dòng)物腸道健康的影響機(jī)制,為科學(xué)禁止添加抗生素及開發(fā)綠色生態(tài)飼料提供理論依據(jù)。
1 材料與方法
1. 1 試驗(yàn)動(dòng)物及其飼養(yǎng)管理
90日齡矮腳黃雞購自江西省農(nóng)業(yè)科學(xué)院畜牧獸醫(yī)研究所,共80羽,平均體重1500±50 g,隨機(jī)分為2組[對(duì)照組(A)和試驗(yàn)組(B)],每組8個(gè)重復(fù),每個(gè)重復(fù)5羽。每個(gè)重復(fù)的矮腳黃雞飼養(yǎng)在同一個(gè)雞籠內(nèi),雞籠底部配有活動(dòng)托盤用于接收糞便。矮腳黃雞飼喂不含任何藥物的全價(jià)配合飼料(由江西省農(nóng)業(yè)科學(xué)院畜牧獸醫(yī)研究所自制),飼料配方見表1。
1. 2 試驗(yàn)方法
參照實(shí)際養(yǎng)殖過程中違禁使用利巴韋林的用藥劑量,每天上午8:00按10 mg/kg的劑量給試驗(yàn)組矮腳黃雞連續(xù)口服利巴韋林溶液7 d,對(duì)照組矮腳黃雞口服等量生理鹽水,每天清理托盤倒掉糞便,最后一次給藥后,在托盤上鋪一張消毒薄膜,收集4 h內(nèi)的新鮮雞糞,混勻裝入消毒好的EP管中,立即放入 -80 ℃超低溫冰箱保存?zhèn)溆谩y(cè)樣時(shí)將雞糞樣品置于冰上解凍,按糞便基因組提取試劑盒說明提取雞糞總DNA(QIAGEN,51504),DNA樣品采用核酸蛋白分析儀(DU640,美國Backman公司)分別測(cè)定260和280 nm處的吸光值,并以1.0%瓊脂糖凝膠電泳(DYY-6C電泳儀,北京六一儀器廠)檢測(cè)DNA質(zhì)量。
根據(jù)細(xì)菌16S rDNA序列V3~V4可變區(qū),設(shè)計(jì)通用引物(338F:5'-ACTCCTACGGGAGGCAGCAG-3'和806R:5'-GGACTACHVGGGTWTCTAAT-3'),PCR擴(kuò)增反應(yīng)體系20.0 μL:5×PCR Buffer 4.0 μL,338F/806R引物(5 μmol/L)各0.4 μL,dNTP Mix(2.5 mmol/L)2.0 μL,DNA聚合酶0.4 μL,DNA模板10 ng,雙蒸水補(bǔ)足至20.0 μL。擴(kuò)增程序:95 ℃預(yù)變性3 min;95 ℃ 30 s,55 ℃ 30 s,72 ℃ 45 s,進(jìn)行27個(gè)循環(huán);72 ℃延伸10 min,結(jié)束后4 ℃保存。PCR擴(kuò)增產(chǎn)物以2.0%瓊脂糖凝膠電泳進(jìn)行檢測(cè),使用Axygen DNA膠回收純化試劑盒(Axy Prep DNA Gel Extration kit,AP-GX-500)進(jìn)行切膠回收純化,經(jīng)Biotek酶標(biāo)儀(FLX800,美國伯騰儀器有限公司)定量分析后,按標(biāo)準(zhǔn)的Illumina TruSeq DNA文庫制備流程構(gòu)建Illumina測(cè)序文庫,然后參照Illumina MiSeq平臺(tái)上機(jī)說明進(jìn)行Barcoded Illumina MiSeq測(cè)序。
1. 3 數(shù)據(jù)處理
原始序列(Raw reads)經(jīng)質(zhì)量控制后得到有效序列(Valid reads),再丟棄長度短于150 bp、含有模糊堿基或引物堿基含2個(gè)以上錯(cuò)配信息、單個(gè)堿基重復(fù)數(shù)超過6個(gè)的序列,即獲得優(yōu)質(zhì)序列(Clean reads)。參照序列相似度為97%的原則,將Clean reads歸為多個(gè)操作分類單元(Operational taxonomic unit,OTU),并進(jìn)行聚類分析。根據(jù)OTU信息進(jìn)行腸道微生物群落豐富度及多樣性分析,豐富度采用Chao1指數(shù)和ACE指數(shù)表示,多樣性采用Shannon指數(shù)和Simpson指數(shù)表示。Shannon指數(shù)越大,說明群落多樣性越高;Simpson指數(shù)越大,則說明群落多樣性越低。在屬分類水平上繪制聚類熱圖,同時(shí)對(duì)微生物群落進(jìn)行UniFrac分析,利用獲得的距離矩陣進(jìn)行PCoA分析和聚類分析,從遺傳距離上判斷不同樣本間的距離,比較不同樣品間的差異性。
1. 4 統(tǒng)計(jì)分析
采用Excel 2010進(jìn)行試驗(yàn)數(shù)據(jù)整理,并以SPSS 22.0的單因素方差分析(One-way ANOVA)進(jìn)行顯著性檢驗(yàn)。
2 結(jié)果與分析
2. 1 矮腳黃雞腸道微生物群落豐富度及其多樣性
Illumina MiSeq高通量測(cè)序結(jié)果表明,從16個(gè)矮腳黃雞糞便樣品中共獲得614626條Raw reads,經(jīng)質(zhì)量控制后獲得606862條Clean reads,平均每個(gè)樣品37929條Clean reads,平均序列長度為442 bp。參照97%的序列相似度進(jìn)行OTU聚類分析,結(jié)果發(fā)現(xiàn)16個(gè)矮腳黃雞糞便樣品共產(chǎn)生968個(gè)OTUs,其中,對(duì)照組樣品的OTU數(shù)目為802個(gè),試驗(yàn)組樣品的OTU數(shù)目為790個(gè),二者共享624個(gè)OTUs(圖1),占總OTU數(shù)目的64.46%;對(duì)照組和試驗(yàn)組樣品的特有OTU數(shù)目分別為178和166個(gè),占總OTU數(shù)目的18.39%和17.15%。說明口服利巴韋林后矮腳黃雞腸道微生物存在一定比例的特有OTU。
矮腳黃雞腸道微生物群落豐富度及其多樣性分析結(jié)果如表2所示。對(duì)照組和試驗(yàn)組的Clean reads差異不顯著(P>0.05,下同);16個(gè)矮腳黃雞糞便樣品的Chao1指數(shù)范圍為605.00~737.92,ACE指數(shù)范圍為591.55~728.78,豐富度指數(shù)表現(xiàn)為對(duì)照組顯著(P<0.05,下同)或極顯著(P<0.01,下同)高于試驗(yàn)組;在物種多樣性方面,Simpson指數(shù)的組間差異不顯著,Shannon指數(shù)則表現(xiàn)為試驗(yàn)組顯著高于對(duì)照組,說明口服利巴韋林改變了矮腳黃雞腸道中的微生物多樣性。對(duì)照組和試驗(yàn)組的文庫覆蓋率(Goods coverage)均在99.00%以上,說明每個(gè)樣品測(cè)序量合理,可很好地反映矮腳黃雞腸道微生物群落結(jié)構(gòu)多樣性。
2. 2 矮腳黃雞腸道微生物組成及其群落結(jié)構(gòu)
采用RDP和BLAST對(duì)16個(gè)矮腳黃雞糞便樣品的OTU進(jìn)行鑒定分析,結(jié)果在門分類水平上共鑒定獲得15個(gè)菌門(圖2),包括厚壁菌門(Firmicutes)、放線菌門(Actinobacteria)、擬桿菌門(Bacteroidetes)、變形菌門(Proteobacteria)、Saccharibacteria、軟壁菌門(Tenericutes)、互養(yǎng)菌門(Synergistetes)、異常球菌—棲熱菌門(Deinococcus-Thermus)、螺旋體門(Spirochaetes)、綠彎菌門(Chloroflexi)、藍(lán)細(xì)菌門(Cyanobacteria)、梭桿菌門(Fusobacteria)、脫鐵桿菌門(Deferribacteres)、疣微菌門(Verrucomicrobia)和迷蹤菌門(Elusimicrobia)。對(duì)照組和試驗(yàn)組均以厚壁菌門、放線菌門、擬桿菌門和變形菌門為優(yōu)勢(shì)菌門,相對(duì)豐度均在5.00%以上,其中以厚壁菌門的相對(duì)豐度最高。
在屬分類水平上,相對(duì)豐度大于0.10%的屬共有108個(gè),表明矮腳黃雞腸道中的菌群微生物非常豐富。對(duì)照組和試驗(yàn)組均以乳桿菌屬(Lactobacillus)的相對(duì)豐度最高,分別為34.07%和19.26%;其次是棒狀桿菌屬(Corynebacterium),對(duì)應(yīng)的相對(duì)豐度分別為9.47%和8.04%(圖3)。通過T檢驗(yàn)對(duì)相對(duì)豐度排名前20位的菌屬進(jìn)行差異顯著性分析,結(jié)果如圖4所示。矮腳黃雞口服利巴韋林后,其腸道中的乳桿菌屬、腸球菌屬(Enterococcus)、Paeniglutamicibacter、Tessaracoccus、埃希氏桿菌屬(Escherichia-Shigella)、副球菌屬(Paracoccus)、Gottschalkia及黃桿菌屬(Flavobacterium)呈顯著或極顯著下降趨勢(shì),而擬桿菌屬(Bacteroides)、葡萄球菌屬(Staphylococcus)、疊球菌屬(Sporosarcina)、Jeotgalicoccus、Unclassified_f_rikenellaceae、Unclassifier_o_bacteroidales、Rikenellaceae_RC9_gut_group、明串珠菌屬(Tri-chococcus)及丹毒絲菌屬(Erysipelothrix)呈顯著或極顯著上升趨勢(shì)。
2. 3 用藥前后矮腳黃雞腸道微生物群落結(jié)構(gòu)的相似性
在屬分類水平上對(duì)相對(duì)豐度排名前50位的菌屬進(jìn)行聚類分析并繪制熱圖。由圖5可知,16個(gè)矮腳黃雞糞便樣品分成兩簇,其中對(duì)照組樣品聚成一簇,試驗(yàn)組樣品聚成一簇,說明同處理組各樣品的微生物群落結(jié)構(gòu)相似,但不同處理組間的微生物群落結(jié)構(gòu)存在明顯差異,試驗(yàn)重復(fù)性良好。
利用UniFrac-PCoA對(duì)用藥前后矮腳黃雞糞便微生物群落結(jié)構(gòu)差異進(jìn)行分析,并通過系統(tǒng)進(jìn)化距離衡量樣品間的相對(duì)距離,用于表征微生物群落結(jié)構(gòu)的差異性,PCoA分析可將這種差異顯示在二維或三維空間,因此,PCoA分析圖中距離越近表示2個(gè)樣品的菌群結(jié)構(gòu)越相似。由圖6可知,基于UniFrac的PCoA分析結(jié)果顯示,第一主成分(PC1)和第二主成分(PC2)的貢獻(xiàn)率分別為73.44%和6.99%,對(duì)照組和試驗(yàn)組間的微生物群落結(jié)構(gòu)差異明顯,彼此間可較好地分隔開,而同處理組內(nèi)的8個(gè)樣品能很好地聚在一起,菌群相似度很高。
3 討論
在家禽養(yǎng)殖生產(chǎn)中,抗生素作為預(yù)防和治療性藥物用于防止疾病發(fā)展和傳播的同時(shí),也廣泛用于提高其生長性能。給肉雞飼喂鹽酸林可霉素、桿菌肽鋅或硫酸粘桿菌素均可顯著提高其日增重(倪江,2013);但抗生素治療已被證實(shí)會(huì)引起腸道微生物群落結(jié)構(gòu)改變甚至紊亂,而造成腸道微生物平衡失調(diào),并對(duì)宿主的生理活動(dòng)及代謝性能產(chǎn)生有害影響,最終可能導(dǎo)致腸道疾病的發(fā)生(Allen and Stanton,2014)。
前人研究證實(shí),雞腸道內(nèi)的微生物群落以厚壁菌門、擬桿菌門、放線菌門和變形菌門為主(Sergeant et al.,2014)。在本研究中,不論是對(duì)照組矮腳黃雞糞便樣品還是試驗(yàn)組矮腳黃雞糞便樣品,均以厚壁菌門、擬桿菌門、放線菌門和變形菌門為主要優(yōu)勢(shì)菌門,且這4種菌門的相對(duì)豐度合計(jì)在99.00%以上。其中,厚壁菌門在對(duì)照組和試驗(yàn)組的相對(duì)豐度均超過50.00%,但藥物干預(yù)后F/B比值由對(duì)照組的6.83下降至3.11。動(dòng)物和人類的肥胖癥與其腸道中的厚壁菌門和擬桿菌門密切相關(guān)。Ley等(2005)、Turnbaugh等(2006)通過對(duì)比肥胖小鼠和瘦弱小鼠盲腸內(nèi)容物的菌群結(jié)構(gòu),發(fā)現(xiàn)肥胖小鼠的擬桿菌門相對(duì)豐度較低,而厚壁菌門相對(duì)豐度較高,F(xiàn)/B比值在肥胖小鼠中偏高,即腸道內(nèi)F/B比值較高時(shí)可提高體內(nèi)脂肪的貯存。B?ckhed等(2004)針對(duì)無菌小鼠的研究也發(fā)現(xiàn),擬桿菌門有促進(jìn)脂肪沉積的作用,且推測(cè)與其能分解植物多糖密切相關(guān)。郭秀蘭(2008)也研究證實(shí),豬的脂肪沉積與腸道擬桿菌門豐度及F/B比值相關(guān),認(rèn)為調(diào)控腸道微生物是控制豬脂肪沉積的有效途徑。本研究結(jié)果表明,在藥物干預(yù)后矮腳黃雞腸道內(nèi)的F/B比值約降低2倍,故推測(cè)添加利巴韋林不利于矮腳黃雞體內(nèi)脂肪的沉積,是由于其腸道微生態(tài)結(jié)構(gòu)平衡被打破所造成。肉雞體內(nèi)的脂肪沉積又分為肌內(nèi)脂肪和腹脂,若能提高肌內(nèi)脂肪并降低腹脂對(duì)動(dòng)物而言非常有利,因此后續(xù)將進(jìn)一步探究利巴韋林藥物干預(yù)對(duì)肉雞肌內(nèi)脂肪和腹脂的影響機(jī)制。
不同抗生素對(duì)動(dòng)物腸道微生物群落結(jié)構(gòu)造成的影響也存在差異(倪江,2013;李會(huì)智,2016;向明等,2019)。Antonopoulos等(2009)研究發(fā)現(xiàn),小鼠使用阿莫西林和甲硝唑聯(lián)合治療后其盲腸區(qū)微生物菌群的豐度和結(jié)構(gòu)發(fā)生顯著變化,治療結(jié)束后菌群結(jié)構(gòu)可迅速恢復(fù),但以頭孢哌酮治療小鼠會(huì)引起腸道微生物菌群多樣性的長期匱乏。李會(huì)智(2016)的研究也表明,在仔豬日糧中添加金霉素、喹乙醇+恩拉霉素、喹乙醇+維吉尼亞霉素均會(huì)降低豬糞便微生物群落多樣性。本研究結(jié)果表明,口服利巴韋林也顯著改變矮腳黃雞腸道的微生物多樣性,且給藥組的腸道微生物多樣性顯著高于對(duì)照組,與劉穎等(2017)研究發(fā)現(xiàn)在仔豬日糧中添加桿菌肽鋅與黏桿菌素后其腸道微生物物種多樣性較基礎(chǔ)飼糧組更豐富的結(jié)論一致??梢?,不同抗生素對(duì)動(dòng)物腸道微生物群落結(jié)構(gòu)及其多樣性的影響存在明顯差異,究其原因可能與抗生素對(duì)不同動(dòng)物的作用機(jī)制差異有關(guān)。
在實(shí)際生產(chǎn)中,亞治療劑量的抗生素能有效促進(jìn)家禽生長(Emami et al.,2012),可能是提高腸道中乳酸菌數(shù)量的緣故(Dumonceaux et al.,2006),但也有研究發(fā)現(xiàn)使用抗生素后機(jī)體的乳酸菌數(shù)量呈降低趨勢(shì)(Lee et al.,2012)。雞腸道菌群結(jié)構(gòu)的變化會(huì)影響其免疫功能和健康狀況,而雞腸道菌群結(jié)構(gòu)的變化受多種因素影響,包括養(yǎng)殖條件、飲食組成及抗生素等(Lee et al.,2012)。倪江和楊維仁(2012)研究發(fā)現(xiàn),在黃雞日糧飼料中添加不同抗生素(鹽酸林可霉素和桿菌肽鋅)不會(huì)顯著改變十二指腸、空腸和回腸中的微生物數(shù)量,但盲腸中的大腸桿菌和雙歧桿菌數(shù)量顯著減少。本研究中,對(duì)照組和試驗(yàn)組的矮腳黃雞腸道微生物群落結(jié)構(gòu)均以乳桿菌屬含量最高,其相對(duì)豐度分別為34.07%和19.26%,且口服利巴韋林后顯著降低了乳桿菌屬相對(duì)豐度。乳桿菌屬是促進(jìn)腸道健康的重要益生菌,對(duì)促進(jìn)免疫細(xì)胞、組織和器官生長發(fā)育及增強(qiáng)小腸和其他組織對(duì)病原菌的抵抗力具有重要意義,且乳酸菌代謝可通過降低腸道pH來抑制致病菌生長。矮腳黃雞口服利巴韋林7 d后其腸道乳桿菌屬含量顯著降低,降幅接近50.0%,說明利巴韋林會(huì)顯著影響肉雞腸道健康及微生物群落結(jié)構(gòu)的穩(wěn)態(tài)性。
此外,使用利巴韋林藥物干預(yù)后,矮腳黃雞糞便樣品中的腸球菌屬相對(duì)豐度由對(duì)照組的7.76%顯著下降至2.47%。腸球菌能產(chǎn)生酪胺,其與酪氨酸的代謝密切相關(guān),可增強(qiáng)細(xì)菌與腸道的黏附性(Ladero et al.,2013)。因此,在選用抗生素治療某一特定細(xì)菌感染引起的相關(guān)疾病時(shí),會(huì)改變整個(gè)腸道的微生態(tài)環(huán)境及該生態(tài)系統(tǒng)與宿主間的相互作用。郭鵬等(2017)研究發(fā)現(xiàn),在β-內(nèi)酰胺藥物治療過程中,腸球菌屬可能在結(jié)腸中生存并合成酪胺,以此提高結(jié)腸黏膜的黏附性。盡管利巴韋林屬于抗病毒藥物,不會(huì)直接作用于腸道細(xì)菌,但矮腳黃雞在口服利巴韋林后仍會(huì)顯著改變其腸道菌群結(jié)構(gòu),故推測(cè)利巴韋林會(huì)導(dǎo)致細(xì)菌與腸道的黏附性下降,其具體原理有待進(jìn)一步探究。
4 結(jié)論
口服利巴韋林會(huì)顯著影響矮腳黃雞腸道微生物區(qū)系,改變腸道微生物的穩(wěn)態(tài)結(jié)構(gòu),進(jìn)而導(dǎo)致其腸道健康受到損傷。
參考文獻(xiàn):
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(責(zé)任編輯 蘭宗寶)