Individual and Synergistic Effects of Metronidazole,Amoxicillin, and Ciprofloxacin on Methane Fermentation with Sewage Sludge

Methane fermentation is widely used to dispose of sewage sludge at wastewater treatment plants (WWTPs), due to production of renewable energy in the form of biogas. Antibiotics present in wastewater may accumulate in a sewage sludge. The aim of the present study is to investigate the impact of three antibiotics from different classes in three different doses on methane production from sewage sludge. For this purpose, metronidazole (MET), amoxicillin (AMO), and ciprofloxacin (CIP) are individually added to anaerobic reactors with sewage sludge collected from municipal WWTP. The antibiotics’ highest concentration (1024 mg kg^?1 of AMO; 512 mg kg^?1 of MET and CIP) lowers methane production and methane content in biogas. MET exerts the most marked effect and lowers methane production to 36.8 ± 3.7 mL CH₄ kg^?1 volatile solids. Tested antibiotics probably inhibit methanogenic archaea, which results in volatile fatty acids (VFAs) accumulation. Addition of MET results in accumulation of many kinds of VFAs with the highest concentration of acetic acid (17.52 ± 1.85 g L^?1). The addition of of AMO results in accumulation of butyric acid only (253.00 ± 15.89 g L^?1). However, addition of CIP results in accumulation of mainly acetic acid (7.58 ± 0.82 g L^?1) and isovaleric acid (2.01 ± 0.41 g L^?1). Next, synergistic effect of these antibiotics in a low concentration of 16 mg kg^?1 of AMO, 8 mg kg^?1 of MET, and 2 mg kg^?1 of CIP is measured in semi‐continuous conditions and causes inbibition of methane production and accumulation of VFAs.     

新疆赛里木湖近岸表层水典型抗生素的赋存与风险评价

利用超高效液相色谱-串联质谱联用技术(UPLC-MS/MS)检测了2019年3月份和7月份新疆赛里木湖近岸表层水中12种抗生素的浓度水平,分析了赛里木湖表层水中典型抗生素的时空分布特征及生态风险.结果表明,氧氟沙星和磺胺甲恶唑为赛里木湖中主要抗生素污染物,春季最高检出浓度分别为2.7×10~4和1.8×10~3ng/L,其次为红霉素(71.7ng/L)和土霉素(15.9 ng/L),其余抗生素浓度均小于10.0 ng/L.与其他湖泊或河流地表水相比,赛里木湖抗生素浓度除磺胺甲恶唑和氧氟沙星外,基本处于中等或低水平.由于人类活动和水力流动等因素,抗生素浓度存在时空分布差异,夏季抗生素浓度比春季低2～4个数量级;位于养殖区内的S1点位抗生素总浓度明显高于其他点位.风险评估结果表明,春季红霉素、氧氟沙星和磺胺甲恶唑对赛里木湖生态环境持高风险(RQ1).     

Neurophysiological control of swimming behaviour,attachment and metamorphosis in black-footed abalone (Haliotis iris) larvae

Experiments were conducted to test the effect of a range of chemicals on larval responses in swimming behaviour, attachment and metamorphosis of the black-footed abalone (Haliotis iris). The effect of antibiotics on larval survival was first tested within negative (filtered seawater) and positive (GABA at 10^?5, 10^?4 and 10^?3 mol L^?1) control assays over 3 days. This experiment corroborated the effectiveness of using antibiotics to improve survival of larvae without obvious synergistic interactions with the GABA inducer or confounding effects of potential bacterial interactions. Chemical treatments (acetylcholine, potassium chloride, dopamine and glutamine) were then tested at various concentrations for their ability to modulate swimming behaviour and induce larval attachment and metamorphosis over 14 days. Generally, larval state shifted from swimming to attached, and from attached to metamorphosed, in the control and treatments over time. However, the peak percentage of attached and metamorphosed larvae varied in time among chemicals and concentrations. While overall percent metamorphosis was minimally enhanced after 14 days of exposure to some chemical treatments at certain concentrations, all treatments displayed significant capacities to down-regulate larval swimming and induce early attachment and metamorphosis. Mortality was recorded throughout the duration of the experiment, and was generally low (<20%) across controls and most treatments for exposures of less than 12 days. Interpretations of specific results from this study are used to elucidate neurophysiological control of larval activities for this abalone species. Comparisons with other marine invertebrates highlight the specificities of chemical cues and endogenous regulatory mechanisms across relatively closely related taxa.     

水产用微生态制剂耐药性评估及耐药相关遗传元件检测

以市场上购买的9种水产用微生态制剂为研究对象,采用琼脂稀释法筛选其中的耐药菌株,运用微量肉汤稀释法检测分离菌株对庆大霉素、恩诺沙星、诺氟沙星、氟苯尼考、磺胺嘧啶、磺胺甲基嘧啶、四环素、土霉素、万古霉素9种抗生素的耐药性,结合聚合酶链式反应分析耐药菌株携带的耐药基因和可移动遗传元件(接合性质粒遗传标记、转座子、整合子和插入序列),为微生态制剂的安全生产与监测提供参考。结果显示,9种微生态制剂中都存在耐药菌株,100株分离菌株对除恩诺沙星以外的8种抗生素都存在不同程度的耐药, 46%的株菌同时携带氟喹诺酮类、酰胺醇类、磺胺类、四环素类、氨基糖苷类和糖肽类耐药基因,且有15株菌同时携带整合子-基因盒、质粒、转座子和插入序列,携带两种及两种以上可移动遗传原件的比例为95%。微生态制剂产品可能存在一定的安全隐患,应加强质量监测和市场监管。     

双河洞放线菌多样性和抗菌活性的初步研究——以阴河洞和杉林洞为例

放线菌是微生物中重要的药用菌,其产生的抗生素是20世纪医学皇冠上最耀眼的明珠,但随着抗生素滥用,抗生素耐药现象日趋严重,因此从特殊生态环境中发现新放线菌物种和新抗生素克服耐药是科研人员正在尝试的途径之一,文章初步探究双河洞系统中阴河洞和杉林洞两个支洞的放线菌多样性,并对分离菌株的抗菌活性进行筛选。以纯培养方法获得放线菌,以16S rRNA基因序列比对,分析菌株类别,获得的菌株进行液体发酵,纸片琼脂扩散法测定其发酵产物对真菌和细菌的抗菌活性,同时用PCR技术进行NRPS、PKS I和PKS II抗生素生物合成基因的探测。从两个支洞样品中分离到的放线菌分布于7个科10个属,两个洞共66株放线菌中有32株的发酵产物在至少一个抗菌活性筛选中显示阳性,总阳性率为48.5%。抗生素生物合成基因的初步探测结果显示,31株菌存在至少一个生物合成基因,NRPS 28株,PKS I17株,PKS II 21株,其中12株同时具有3种生物合成基因。初步显示了双河洞系统蕴含丰富的放线菌资源,值得深入研究。      

Axenic culture of free-living conchocelis of<Emphasis Type="Italic">Porphyra yezoensis</Emphasis> and<Emphasis Type="Italic">Porphyra haitanensis</Emphasis>

After discarding marine microorganisms from conchocelis of Porphyra yezoensis and Porphyra ha/tanens/s, their axenic cultures were obtained through treatment with antibiotics. Antibiotic disc tests were carried out to determine the effectiveness of each antibiotic in eliminating contaminating microorganisms. Five of 12 antibiotics tested were selected and used to produce the axenic cultures in this study, which showed that 200 μg/mL streptomycin, 250 μg/mL penicillin, 252 μg/mL kanamycin, 30 μg/mL neomycin, 200 μg/mL chloramphenicol were effective concentrations for eliminating microorganisms from conchocelis when antibiotics were added singly step by step; whereas simultaneous combination of 150 μg/mL streptomycin, 250 (or 350) μg/mL penicillin, 150 (or 250) μg/mL kanamycin, 70 μg/mL neomycin and 200 μg/mL chloramphenicol was also effective for producing the axenic cultures. However,it seemed that the treatments with antibiotics applied individually were more feasible than those with all antibiotics added at the same time. This may be due to the combined inhibiting effect of antibiotics on the growth and development of conchocelis.     

浒苔原生质体再生苗对草丁膦与6种抗生素的敏感性

浒苔(Ulva prolifera)是构成黄海绿潮的优势种,通过构建浒苔稳定转化系统,可以为相关基因功能验证提供有力工具。本文以浒苔原生质体再生苗为材料,试验了对除草剂草丁膦和6种抗生素的敏感性,发现浒苔对氨苄青霉素、卡那霉素、硫酸链霉素、Zeocin 4种抗生素不敏感,对氯霉素、潮霉素较敏感,对除草剂草丁膦极为敏感,进一步统计得出草丁膦对浒苔的半致死剂量(LD50)和95%可信限,发现敏感性与光周期明显相关。上述结果为进一步筛选转化子、构建浒苔稳定转化系统打下了基础。     

海水养殖鱼类鳗弧菌(Vibrio anguillarum)临床分离株的血清型和抗生素耐药谱

鳗弧菌(Vibrio anguillarum)是常见的海水鱼类病原菌,有23种血清型,其中O1—O3为主要的致病血清型。我国海水养殖鱼类鳗弧菌的血清型种类尚未明确。本研究对实验室分离和收集自海水养殖鱼类的31株鳗弧菌临床菌株进行了生理生化、16S r RNA基因序列、血清分型、抗生素敏感性的分析,旨在系统了解存在于我国海水养殖环境的鳗弧菌血清学型及耐药特征。首先用API ID32E生化反应鉴定系统对鳗弧菌进行生理生化鉴定,结果未能将待测菌株鉴定到种的水平;然后测定鳗弧菌的16S r RNA基因序列并构建系统发育树,结果显示所有分离株聚为一簇,与鳗弧菌有最近的亲缘关系(相似性99%—100%),据此可将临床菌株鉴定为鳗弧菌。以鳗弧菌O1—O5血清型标准菌株为O抗原制备兔抗血清,采用玻片凝集反应对鳗弧菌菌株进行血清学分析,结果显示属于O1、O2、O3、O5血清型菌株分别有16、5、3、1株,表明我国海水鱼类养殖存在3种血清型的致病性鳗弧菌,O1为主要流行的血清型。用ATB药敏检测系统检测鳗弧菌对28种抗生素的敏感性,结果显示菌株对7种抗生素(林可霉素、夫西地酸、甲硝唑、阿莫西林、阿莫西林/克拉维酸、苯唑西林、青霉素)的耐药率为100%,对3种抗生素(红霉素、原始霉素、泰洛星)的耐药率为94.4%(34株),有83%以上的菌株(30株)对12种以上的抗生素产生耐药,表明我国海水鱼类养殖鳗弧菌普遍存在多重耐药性。研究结果为进一步揭示鳗弧菌的流行病学规律和防控弧菌病奠定了良好的基础。     

8种抗生素对塔玛亚历山大藻生长的影响

对一株有毒的塔玛亚历山大藻(Alexandrium tamarense(Lebour) Balech)进行了8种抗生素-氯霉素、红霉素、林可霉素、庆大霉素、金霉素、氨苄青霉素、新霉素和链霉素的敏感性实验.结果表明,该藻对抗生素较为敏感.其中的5种:氯霉素、红霉素、林可霉素、庆大霉素和金霉素,对藻8d比生长速率的EC₅₀分别为2.45μg/cm3,25.2μg/cm3,7.95μg/cm3,285u/cm3,58.7μg/cm3,可用作该藻基因工程的选择压力,其对应的抗性基因可以作为基因工程阳性选择标记基因,应用于塔玛亚历山大藻的遗传操作研究.新霉素和链霉素对A.tamarense的生长无明显抑制作用,可以用于藻株无菌化培养而应用于甲藻产毒机制和赤潮爆发机理的研究,还应用筛选出的抗生素对藻培养物进行了除菌实验.