Studies on the Isolation of Endophytic Bacteria from Tomato Plants and Their Growth-promoting Activities

[Objective] The study aimed to investigate the growth-promoting activities of endophytic bacteria from tomato plants.[Method]The endophytic bacteria isolated from different tissues of tomato plants were analyzed for the effects of their growth-promoting activities on the germination and growth of tomato plants.The bacteria with growth-promoting activity were preliminarily identified.[Result]Totally 59 endophytic bacterial strains were isolated from roots and stems of tomatoes,of which 4 showed significantly growth-promoting activity to germination and growth of tomato.The results suggest that these strains are endowed with the potential capability of growth-promoting.[Conclusion]The endophytic bacteria with growth-promoting activity were found among the isolates from tomato plants.This provided a good foundation for utilization of these bacteria with growth-promoting activity.

Isolation and Identification of High-Quality Lactic Acid Bacteria in Forage Corn

[ Objective] To screen suitable lactic acid bacterium strains from forage corn which can be used as silage additives. [ Method] The lactic acid bacterium strains were isolated by inoculation on MRS solid medium containing calcium carbonate, and they were preliminarily identified through morphological, physiological and biochemical experiments. The acid production efficiency was determined. Twelve strains having strong acid-pro- duction ability were selected, and their salt tolerance and acid tolerance were detected. The sequences of their 16 S rDNA were also analyzed. [ Result] A total of 44 lactic acid bacterium strains were isolated from the forage com. As evidenced by the physiological and biochemical experi- ments, the twelve strains having strong acid-production ability belonged to Leuconostoc, Lactobacillus and Enterococcus, respectively, and they had strong salt tolerance and acid tolerance. According to the sequences of 16 S rDNA, A4, B9, B11, B12 and B14 were Lactobacillus plantarum; A1, A2., A7, A11 and B8 were Leuconostoc mesenteroides dextran subspecies; and AB and A9 were Enterococcus hirae. [ Conclusion ] The lactic acid bacterium strains with strong acid-production ability isolated from forage corn can be developed into silage additives.

Isolation and characterization of halophilic bacteria and archaea from salt ponds in Hangu Saltworks, Tianjin, China

A total of 26 isolates were obtained from solar salt ponds of different salinities(100, 150, 200, and 250) in Hangu Saltworks Co. Ltd., Tianjin, China. Phylogenetic analysis of 16 SrRNA gene sequences indicated that five bacteria genera H alomonas, Salinicoccus, Oceanobacillus, Gracibacillus, and Salimicrobium and one archaea genera H alorubrum were present. The genus H alomonas was predominant with eight strains distributed in a salinity range of 100–200, followed by H alorubrum with six strains in salinity 250. Based on the genus and original sampling salinity, eight bacterial and two archaeal isolates were selected for further morphological, physiological, and biochemical characterization. All of the bacterial strains were moderately halophilic with the optimal salinity for growth being either 50 or 100, while two archaeal strains were extremely halophilic with an optimal growth salinity of 200. Additionally, we put forth strain SM.200-5 as a new candidate S alimicrobium species based on the phylogenic analysis of the 16 SrRNA gene sequence and its biochemical characteristics when compared with known related species.

Evaluation of the new OxyPlate^(TM) Anaerobic System for the isolation of ocular anaerobic bacteria

AIM: Anaerobic bacteria can cause ocular infections. We tested the OxyPlateTM Anaerobic System (OXY) to isolate pertinent anaerobic bacteria that can cause ocular disease.METHODS: OXY, which does not require direct anaerobic conditions (i.e. bags, jars), was compared to conventional isolation of incubating culture media in anaerobic bags. Standard colonies counts were performed on anaerobic ocular bacterial isolates under aerobic and anaerobic conditions (anaerobic bags) using agar media: 1) OXY (aerobic only), 2) 5% sheep blood (SB), 3) Chocolate, and 4) Schaedler. The bacteria tested were de-identified ocular isolates cultured from endophthalmitis and dacryocystitis that include 10 Propionibacterium acnes and 3 Actinomyces species. The colony counts for each bacteria isolate, on each culturing condition, were ranked from largest to smallest, and non-parametrically compared to determine the best culturing condition.RESULTS: All anaerobic conditions were positive for all of the anaerobic isolates. SB and Schaedler’s agar under aerobic conditions did not support the growth of anaerobic bacteria. Sparse growth was noted on chocolate agar with Propionibacterium acnes . As an anaerobic system, SB in an anaerobic bag isolated higher colony counts than OXY (P=0.0028) and chocolate agar (P=0.0028).CONCLUSION: Although OXY did not test to be more efficient than other anaerobic systems, it appears to be a reasonable alternative for isolating anaerobic bacteria from ocular sites. The use of an agar medium in a specially designed plate, without the requirement of an anaerobic bag, rendered OXY as an advantage over other anaerobic systems.

Isolation and Identification of High-Quality Lactic Acid Bacteria from Wheat Haulm

[Objective] The aim of this study was to isolate and identify lactic acid bacteria （LAB） from wheat haulm and to select efficient strains for silage fermentation. [ Method] From 78 LAB strains isolated on the MRS solid medium containing calcium carbonate, we selected 43 strains having better acid-production ability through morphological observation, Gram staining, physiological and biochemical tests, acid production test, acid tolerance test and salt tolerance test. These strains were finally identified by sequencing 16 S rDNA. [ Result] Of the 43 LAB strains having better acid-production ability, 37 belonged to Lactobacillus paracasei subsp., one belonged to Lactobacillus rhamnosus and five belonged to Enterococcus faecium, as shown by the sequences of 16 S rDNA. [ Conclusion ] A total of 43 LAB strains having better acid-production ability were selected, which may be developed as high-quality silage additives.

Isolation and Characterization of Multi-Drug Resistant Bacteria from Hospital Wastewater Sites around the City of Aizawl, Mizoram

A microbial study was conducted from wastewater soils of hospitals in Aizawl, Mizoram, India which were in existence for a longtime. The isolated bacteria from the wastewater soils were found to be mainly of Morganella morganii and Bacillus cereus and these isolated bacteria were found to be very resistant to a wide range of antibiotics and heavy metals. Antibiotics that were used for treating infections caused by these bacteria like chloramphenicol and ciprofloxacin were also found to be insensitive. The degree of resistance was also very high when compared to earlier reports of antibiotic resistance observed in the corresponding bacteria. Our results suggested that the high degree of resistance is probably conferred by the continued exposure to antibiotics from hospital waste leading to a selected population of highly antibiotics-resistant bacteria.

Isolation and Screening of Cd-tolerant Bacterial Strains from Paddy Soils around Lead-zinc Tailings

Microorganisms being used in Cd-contaminated soil remediation have broad prospects in application.In order to obtain more Cd-tolerant microbial resources,paddy soils around lead-zinc tailings were collected to extract Cdtolerant bacterial strains by using the methods of enrichment culture,purification and gradient screening.The strains were identified by morphological and biochemical characteristics and 16S rDNA sequence analysis.The Cd-tolerance and Cdadsorption abilities were then analyzed.The results showed that 6 Cd-tolerant bacterial strains were isolated,3 strains could grow in solid medium which had a cadmium concentration of 700 mg/L.These three strains(i.e.KGJ,KDT,and TU)were members of the Pseudomonas genus(Pseudomonas sp.)identified by morphological and biochemical characteristics and 16S rDNA sequence analysis.The growth curve indicated that the growth rates of the strains were obviously inhibited under 250 mg/L cadmium treatment.The three strains were tolerant of cadmium concentrations over 250 mg/L for long periods of time up to the stationary phase,and TU had the strongest Cd-tolerance.The order of metal tolerance of TU to different heavy metals was Cd^2+ >Zn^2+ >Pb^2+respectively.Chemical analysis showed that the adsorption quantity of the 3 bacterial strains of KGJ,KDT,and TU were 7.596 mg/g,12.237 mg/g and 36.926 mg/g respectively by dry-weight,when the concentration of cadmium was 150 mg/L.All 3 strains had good tolerance and ability to adsorb cadmium,and therefore are considered important potential microbial resources for the remediation of Cd pollution in soil.

Isolation and Screening of Rhizobacteria from Scirpus Grossus Plant after Lead （Pb） Exposure

Phytoremediation is one of method which can be applied to remediate the contaminated environment. In most cases, microorganisms bacteria and fungi, living in the rhizosphere closely associated with plants, may contribute to mobilize metal ions by increasing the bioavailable fraction. Some studies have evidenced that heavy metal-resistant bacteria can enhance metal uptake by hyperaccumulator plants. Lead-resistant bacteria which could help to increase the lead uptake by Scirpus grossus was isolated and screened. The samples were taken from plant roots after being exposed in a range finding test by spiking analytical grade of Pb（NO3）2 solution in variation of Pb concentrations. The results of rhizobacteria isolation showed that there were several colonies having resistance to grow and survive in contaminated environment even the host plant had withered. Only a few of rhizobacteria colonies were affected by high concentrations of lead exposure during screening test. The screening test was conducted by growing the isolated colonies on plates containing tryptic soy agar （TSA） medium containing of 200, 400 and 600 mg/L Pb solution including the plate with only TSA media without any lead exposure acting as a control medium, and incubating them at 30℃ for 72 hours. Isolation of bacteria from rhizosphere had found 47 colonies including several colonies from the withered plants. These all 47 colonies then become 28 after characterization by using color and colony morphology, followed by Gram stain, catalase, oxidase and motility test. The screening test of lead resistant bacteria colonies resulted 3 groups which is scored high, medium and low. The screened colonies will then be used for further study.

Isolation of New Strains of Bacteria Able to Synthesize 1,3-Propanediol from Glycerol

The natural environment is inhabited by many species that exhibit very specific metabolic activities that may find industrial applications. The aim of the study was to select non-pathogenic cultures of bacteria of the genus Clostridium and lactic acid bacteria able to convert glycerol into 1,3-propanediol (1,3-PD). Another aim of this study was to identify the isolates that best produced 1,3-propanediol both from pure and crude glycerol. The most efficient strains identified (Cl. butyricum) were analysed on a bioreactor scale. The aim was to determine temperature conditions on the efficiency and duration of 1,3-PD synthesis. The species Clostridium were identified using amplification of the 16S rRNA coding sequence. A total of 123 isolates (of the genus Clostridium and lactic acid bacteria) were isolated;a vast majority of these were able to synthesize 1,3-PD. The best results were obtained for Cl. butyricum strain DSP1, which was isolated from the rumen of a cow fed with glycerol. The strain efficiency using pure glycerol on bioreactor scale 0.65 mol/mol of glycerol at a temperature of 38℃ and a constant pH of 7.0.

林麝肠道中乳酸菌的分离筛选及益生特性

本研究旨在从健康林麝粪便中分离筛选用于改善林麝健康状况的潜在益生菌株,并对其进行体外益生性评价。共分离获得12株乳酸菌,结合细胞个体形态观察及细菌16S rDNA序列鉴定,体外评价其耐酸和耐胆盐能力,测定其对5种目标病原菌(大肠埃希氏菌Escherichia coli ATCC 25922、金黄色葡萄球菌Staphylococcus aureus ATCC 25923、铜绿假单胞菌Pseudomonas aeruginosaPAO1、肠炎沙门氏菌Salmonella enteritidisATCC 13076和化脓隐秘杆菌Arcanobacterium pyogenes LSN3)的拮抗活性、自聚集和疏水性、抗生素敏感性、抗药性基因型和生长曲线。结果显示,5株植物乳植杆菌(Lactiplantibacillus plantarum)和1株乳酸片球菌(Pediococcus acidilactici)在pH 4酸性条件或质量分数0.5%胆盐环境中,存活率分别达88.5%和87%以上;能够抑制前4种目标病原菌(抑菌圈直径17.20~20.19 mm)和化脓隐秘杆菌LSN3(抑菌圈直径14.23~15.53 mm);与对照菌株副干酪乳酪杆菌(L. paracasei)L22具有相近的自聚集(53.1%~56.2%)和表面疏水率(52.9%~56.0%);对链霉素、环丙沙星和万古霉素耐药;携带万古霉素抗性基因vanX;具有快速生长的特点(培养24 h后OD600分别达9.0和7.1左右)。本研究筛选出的6株乳酸菌可作为后续开发林麝用益生菌制剂的一种可靠的菌株来源。

The assessment of good and bad bacteria in holy basil(Ocimum sanctum)leaves

Holy basil(Tulsi,Ocimum sanctum)is considered to be a pious plant.It is used not only in many of the rituals of Hindus but is also known for its innumerable medicinal qualities.Holy basil leaves(HBLs)are often consumed raw thus it is pertinent to detect the bacteria on Tulsi leaves.This study was conducted to understand the diversity of the aerobically growing microbiome of edible holy basil leaves.A total of 112 samples of leaves were collected from households of six localities in and around Bareilly,India for detecting culturable bacteria growing aerobically.A sum of 579 bacterial isolates belonging to 106 different species was identified.Pantoea agglomerans isolates were detected in 43 samples followed by isolates Virgibacillus pantothenticus(21),Bacillus coagulans(18),Bacillus cereus(17),Geobacillus stearothermophilus(16),Klebsiella pneumoniae(13),Citrobacter freundii(12),Lysinibacillus sphaericus(12),Acinetobacter calcoaceticus(11),Escherichia coli(11),and Xenorhabdus bovienii(11).Isolates of 95 species of bacteria were detected on<10 samples of HBLs.Of 579 isolates,161 isolates detected in 68(60.71%)samples were of putatively good bacteria belonging to eight genera(Bacillus,Brevibacillus,Lysinibacillus,Paenibacillus,Photobacter,Siccibacter,Virgibacillus,Xenoirhabdus)and 23 species.However,418 bacterial isolates detected in 108(96.43%)of the HBL samples were classified as potentially pathogenic for humans and animals belonging to 34 genera and 73 species.There were only four samples(three from Mahanagar and one from Bhojipura)that had no potential pathogenic bacteria detected in this study.The analysis indicated that HBL leaves from the ICAR-IVRI campus had a lower probability(P<0.04)of harbouring good bacteria than samples from Bhojpura,Mahanagar,North City and Rajendra Nagar.Cinnamaldehyde inhibiting 96.72%of the isolates and carvacrol inhibiting 96.37%of the isolates were the best herbal antimicrobials and among antibiotics,meropenem inhibited 98.96%of bacterial isolates.Antimicrobial resistance in non-pathogenic or good bacteria was significantly more common(P<0.01)for ajowan oil but they were more often(P<0.05)susceptible to holy basil oil,lemongrass oil,citral,P.embalica leaf extract,P.longifolia seed oil,nitrofurantoin,ciprofloxacin,chloramphenicol,colistin and minocycline than isolates of potentially pathogenic bacteria.The study concludes that HBLs may harbour both good and bacteria,and should be consumed raw only after proper decontamination.

大豆镰刀菌根腐病拮抗菌的筛选及生防效果

【目的】镰刀菌根腐病是世界范围内大豆生产上最具破坏性的土传病害之一,为获得对禾谷镰刀菌Fusarium graminearum具有较好拮抗效果的生防菌株。【方法】从健康大豆根际土壤分离细菌,平板对峙法筛选拮抗菌株,通过形态观察、生理生化特性、胞外酶活性及促生特性对菌株进行鉴定分析,采用盆栽试验进一步测定菌株生防及促生效果。【结果】筛选出的4株芽孢杆菌和1株假单胞杆菌对F.graminearum的抑菌率均达到60%以上,对F.oxysporum,F.solani,F.longifundum以及F.equiseti也均有一定的抑制作用,其发酵液及挥发代谢物均会影响F.graminearum的生长。5株拮抗菌具有产蛋白酶、纤维素酶以及葡聚糖酶的活性,解磷、解钾、固氮以及产铁载体的能力。综合以上测试结果,菌株20-8具有较强的抑菌及大豆促生效果。根据形态特征及16S rRNA序列分析,将菌株20-8鉴定为暹罗芽孢杆菌(Bacillus siamensis)。该菌株的发酵上清液可以破坏F.graminearum菌丝体结构,无细胞发酵上清液可以显著抑制孢子萌发。室内盆栽防效测定结果表明,20-8的稀释发酵液对F.graminearum引起大豆根腐病的防效可达46.08%,并且促进大豆植株生长。【结论】筛选鉴定的暹罗芽孢杆菌20-8具有解磷、解钾、固氮以及产铁载体及多种胞外酶功能,其稀释发酵液具有较强的抗真菌活性及大豆促生能力,菌株20-8可以用于防治F.graminearum引起的大豆根腐病。

一株降解黄曲霉毒素B_(1)、拮抗黄曲霉的菌株鉴定及应用研究

目的筛选、鉴定一株降解黄曲霉毒素B_(1)(aflatoxin B_(1),AFB_(1))及拮抗黄曲霉的菌株,并进行应用研究。方法以青岛市海洋、陆地、河流等不同地区的土壤、水质微生物为研究对象,利用平板划线法、AFB_(1)降解率和黄曲霉对峙试验法筛选得到有效菌;通过形态学观察和同源性分析,鉴定有效菌的种类;分离该菌的上清液、悬菌液、胞内液并对各组分的AFB_(1)降解率进行测定;提取有效菌的活性物质,对其提取物进行抑菌试验;主动侵染花生籽仁,验证有效菌对降解AFB_(1)及抑制黄曲霉生长的效果。结果通过筛选,得到有效菌株LE160。综合形态学特征和16S rRNA基因分析结果,鉴定菌株LE160为毕节假单胞菌(Pseudomonas bijieensis),命名为毕节假单胞菌LE160。该菌株胞外上清液、菌悬液和胞内液对AFB_(1)降解率分别为80.4%、16.3%、11.9%。该菌降解AFB_(1)不是依赖细菌胞体的吸附作用,而是细菌代谢产生并分泌至胞外的活性物质主导的生物降解作用。菌株提取液对黄曲霉菌有明显抑制作用。花生应用试验结果表明该菌株的发酵液对降解AFB_(1)及抑制黄曲霉生长有一定效果。结论菌株LE160对AFB_(1)具有良好的降解效果,能有效拮抗黄曲霉的生长,具有应用的潜力。本研究结果为深入研究该菌的降解机制奠定了基础,也为花生等农产品防控黄曲霉侵染提供了新思路。

湖南省细菌耐药监测网2012-2021年血标本分离细菌耐药性监测报告

目的了解湖南省血标本分离细菌的分布及耐药性变迁,为临床血流感染初始经验诊治提供依据。方法收集湖南省细菌耐药监测网2012—2021年各成员单位上报数据,细菌耐药监测方法参照全国细菌耐药监测网(CARSS)技术方案执行,应用WHONET 5.6软件和SPSS 27.0软件对血标本分离细菌及药敏试验结果进行分析。结果2012—2021年湖南省细菌耐药监测网成员单位血标本共分离细菌207054株,其中革兰阳性菌107135株(51.7%)、革兰阴性菌99919株(48.3%);2012—2021年居前6位的病原菌无变化,居首位的为大肠埃希菌(51537株,24.9%),其次分别为表皮葡萄球菌(29115株,14.1%)、金黄色葡萄球菌(17402株,8.4%)、肺炎克雷伯菌(17325株,8.4%)、铜绿假单胞菌(4010株,1.9%)和鲍曼不动杆菌(3598株,1.7%)。耐甲氧西林金黄色葡萄球菌(MRSA)的检出率由2015年的30.3%下降至2021年的20.7%,耐甲氧西林凝固酶阴性葡萄球菌(MRCNS)的检出率呈逐年上升趋势(57.9%~66.8%)。未发现对万古霉素、利奈唑胺和替考拉宁耐药的葡萄球菌。革兰阴性菌中,大肠埃希菌、肺炎克雷伯菌构成比分别为43.9%~53.9%、14.2%~19.5%,呈上升趋势(均P<0.001);铜绿假单胞菌、鲍曼不动杆菌的构成比分别为3.6%~5.1%、3.0%~4.5%,呈逐年下降趋势(均P<0.001)。2012—2021年大肠埃希菌对亚胺培南、厄他培南的耐药率分别为1.0%~2.0%、0.6%~1.1%,呈下降趋势(均P<0.001)。肺炎克雷伯菌对美罗培南、厄他培南的耐药率分别为7.4%~13.7%、4.8%~6.4%,呈下降趋势(均P<0.001)。铜绿假单胞菌、鲍曼不动杆菌对碳青霉烯类抗生素的耐药率分别为7.1%~15.6%、34.7%~45.7%,对碳青霉烯类抗生素的耐药性趋势相对稳定,但与2012—2016年相比均有下降。2012—2021年大肠埃希菌对第三代头孢菌素的耐药率为41.0%~65.4%,呈逐年下降趋势。结论湖南省血标本革兰阴性杆菌构成比逐年增高,耐碳青霉烯类革兰阴性杆菌的检出率近5年相对稳定,凝固酶阴性葡萄球菌检出率呈下降趋势。

高光学纯度乳酸菌株的筛选及发酵性能研究

从不同地区的土壤、泡菜中分离筛选出了2株高光学纯度D-乳酸菌株和2株高光学纯度L-乳酸菌株。通过形态学观察、生理生化鉴定和16S rDNA序列分析,确定L-乳酸产生菌HA7-5菌株为屎肠球菌(Enterococcus faecium),HJ57菌株为格氏乳球菌(Lactococcus garvieae);D-乳酸产生菌HB49-2菌株为德氏乳杆菌(Lactobacillus delbrueckii),HL64-1菌株为假肠膜明串株菌(Leuconostoc pseudomesenteroides)。经摇瓶发酵产酸培养,菌株HA7-5和HJ57发酵产L-乳酸分别达71.83 g/L和31.89 g/L;菌株HB49-2和HL64-1发酵产D-乳酸分别达73.14 g/L和62.04 g/L,且菌株HL64-1发酵周期仅为24 h,产酸速率快,平均产酸速率为2.58 g/(L·h)。D体和L体光学纯度均达99.8%(ee)以上。以上菌株均为产高光学纯度L-或D-乳酸野生型菌株,可作为后期诱变育种的出发菌株,进行菌株改良及发酵性能提升的研究。

胎膜早破孕妇阴道微生态和胎盘分离菌及耐药性分析

目的 比较胎膜早破和正常破裂孕妇孕晚期(孕35~37周)阴道微生态、胎盘拭子细菌分布和耐药性情况,为临床预防和治疗提供病原学依据。方法 收集甘肃省妇幼保健院产科2020年1月1日至2022年6月30日胎盘拭子培养结果,将培养阳性的孕妇分成胎膜早破组和正常破裂组,比较两组基本临床特征及孕晚期阴道微生态、胎盘分离菌和药敏结果。结果 两组孕周、年龄、细菌性阴道病和正常微生态情况差异有统计学意义(P<0.05);多因素Logistic回归分析显示孕周(β=-0.711,OR=0.491)和正常微生态(β=-1.412,OR=4.103)与胎膜早破发生呈负相关,年龄(β=0.076,OR=1.079)呈正相关,细菌性阴道病的差异无统计学意义(P>0.05)。两组胎盘主要分离菌为革兰阴性杆菌,差异无统计学意义(P>0.05),以大肠埃希菌为主,检出率差异有统计学意义(P<0.05),胎膜早破组产超广谱β-内酰胺酶比例较高,对氨苄西林、头孢类耐药性高,差异有统计学意义(P<0.05);其次是革兰阳性球菌(粪肠球菌和无乳链球菌为主),差异无统计学意义(P>0.05)。无乳链球菌对青霉素类、糖肽类等敏感,对喹诺酮类耐药率较高;粪肠球菌对青霉素类、糖肽类、恶唑烷酮类等敏感,对红霉素和克林霉素的耐药性较高。结论 胎膜早破组年龄偏大且孕周小,孕晚期易发生阴道微生态异常,其胎盘拭子大肠埃希菌检出率、对青霉素和头孢类抗生素耐药性较高。

湖南某规模奶牛场乳房炎病原菌的分离鉴定与耐药性分析

为明确湖南某规模奶牛场临床型乳房炎病原菌种类及耐药情况,对32份临床型乳房炎患牛乳样进行传统细菌培养、生化试验、16S rDNA核苷酸序列检测和药敏试验。结果共分离鉴定大肠杆菌23株,乳房链球菌12株,肺炎克雷伯氏菌5株,样品检出率分别为71.9%(23/32)、37.5%(12/32)、15.6%(5/32);药敏试验显示,大部分大肠杆菌和乳房链球菌对青霉素、阿莫西林、头孢他啶、庆大霉素、林可霉素耐药严重,耐药率达50%~86.9%,对亚胺培南、四环素及红霉素较敏感,敏感率达75%~82.6%;肺炎克雷伯氏菌对大部分抗生素耐药程度较低,对亚胺培南、阿米卡星、四环素、红霉素敏感率为100%。建议该养殖场抓好环境卫生、提高生物安全,建立科学、合理治疗方案。

基于微生物高通量分离技术的白星花金龟幼虫消化道玉米秸秆降解菌筛选

白星花金龟幼虫在转化玉米秸秆过程中,其肠道微生物发挥关键作用。为获得优良秸秆降解菌株,研究通过优化秸秆提取物(Straw extract,SE)提取参数,制备SE培养基,采用高通量分离培养方法,从白星花金龟幼虫后肠分离得到1128株细菌,微生物可培养率为42.1%。从中筛选到纤维素降解菌409株,木质素降解菌669株。测定部分菌株降解率,结果表明,菌株P61-C4、P63-G12-1和P62-D4-2对滤纸条降解率分别为45.6%、31.7%、26.8%;菌株P61-C7-1、P61-C6-2、P61-C10-1对木质素磺酸钠降解率分别为50.5%、30.6%、25.1%。研究结果明确白星花金龟幼虫肠道微生物对转化玉米秸秆的作用,丰富秸秆生物降解菌株资源,对促进农业可持续发展具有重要意义。

规范ICU多重耐药菌感染病人接触隔离的循证护理实践

目的:提高重症监护病房(ICU)医护人员接触隔离管理水平及最佳证据执行能力,降低ICU多重耐药菌医院感染发生率。方法:运用循证护理方法获取最佳证据,制定多重耐药菌感染病人接触隔离管理审查指标并用于临床进行持续质量改进,比较证据应用前后ICU多重耐药菌医院感染发生率、医护人员对多重耐药菌感染病人接触隔离相关知识知晓情况及执行情况。结果:本研究形成21条质量审查指标,应用最佳证据后,ICU医护人员多重耐药菌接触隔离理论知识评分由(73.49±6.50)分提高到(92.88±6.27)分;接触隔离措施依从性大幅提升,13条审查指标执行率提升至88%以上,差异均有统计学意义(P<0.05),ICU多重耐药菌医院感染率从3.2%降低至1.9%。结论:将基于循证的最佳证据应用于临床,有助于推进ICU多重耐药菌感染病人接触隔离管控措施落实,提升医护人员理论知识及实践水平,降低ICU多重耐药菌医院感染发生率。

一株新型高效聚磷菌Glutamicibacter sp.G2的分离鉴定及除磷特性

聚磷菌(Phosphorus accumulating bacteria,PAOs)在生物除磷系统(EBPR)的强化过程中发挥着重要作用。挖掘新型高效聚磷菌并优化其除磷工艺,对于废水生物除磷技术的发展具有重大意义。文章通过富集驯化、分离纯化,结合MOPS蓝白斑(10×)初筛、Albert异染颗粒复筛等方法从某污水处理厂污泥样品中筛选出一株高效聚磷细菌G2,将其鉴定为盐生谷氨酸杆菌(Glutamicibacter halophytocola),并通过单因素试验探究pH、温度、接种量、初始磷含量,以及水体中的阳离子浓度对菌株G2生长及除磷的影响。实验结果表明,该菌株在初始磷浓度为30 mg/L、pH为8.0、8.0%接种量、32℃的条件下发酵72 h后,磷去除率可达78.79%。同时,添加2.0%的Mg^(2+)可以将菌株G2在人工合成废水中的除磷率提高17.50%。文章所筛选出的盐生谷氨酸杆菌G2在人工合成废水中表现出了良好的除磷效果,有望为废水生物除磷技术提供优质菌种资源。