Microbial background flora in small-scale cheese production facilities does not inhibit growth and surface attachment of Listeria monocytogenes

The background microbiota of 5 Norwegian small-scale cheese production sites was examined and the effect of the isolated strains on the growth and survival of Listeria monocytogenes was investigated. Samples were taken from the air, food contact surfaces (storage surfaces, cheese molds, and brine) and noncontact surfaces (floor, drains, and doors) and all isolates were identified by sequencing and morphology (mold). A total of 1,314 isolates were identified and found to belong to 55 bacterial genera, 1 species of yeast, and 6 species of mold. Lactococcus spp. (all of which were Lactococcus lactis), Staphylococcus spp., Microbacterium spp., and Psychrobacter sp. were isolated from all 5 sites and Rhodococcus spp. and Chryseobacterium spp. from 4 sites. Thirty-two genera were only found in 1 out of 5 facilities each. Great variations were observed in the microbial background flora both between the 5 producers, and also within the various production sites. The greatest diversity of bacteria was found in drains and on rubber seals of doors. The flora on cheese storage shelves and in salt brines was less varied. A total of 62 bacterial isolates and 1 yeast isolate were tested for antilisterial activity in an overlay assay and a spot-on-lawn assay, but none showed significant inhibitory effects. Listeria monocytogenes was also co-cultured on ceramic tiles with bacteria dominating in the cheese production plants: Lactococcus lactis, Pseudomonas putida, Staphylococcus equorum, Rhodococcus spp., or Psychrobacter spp. None of the tested isolates altered the survival of L. monocytogenes on ceramic tiles. The conclusion of the study was that no common background flora exists in cheese production environments. None of the tested isolates inhibited the growth of L. monocytogenes. Hence, this study does not support the hypothesis that the natural background flora in cheese production environments inhibits the growth or survival of L. monocytogenes.     

Research on Great Lakes Algal Communities: Problems from the Past,Lessons for the Future

Review of research on algal communities in the Laurentian Great Lakes shows significant progress in delineating this component of the biota and understanding the factors which regulate its composition and distribution. Unaddressed or poorly addressed problems remain in certain fundamental research areas and future progress will depend largely on how quickly and thoroughly these problems are reduced. It is clear that there is no useful distinction between basic and applied research in this area and best progress will be achieved through a balanced approach.     

MORE EXOTIC AND FEWER NATIVE PLANT SPECIES: RIVERINE VEGETATION PATTERNS ASSOCIATED WITH ALTERED SEASONAL FLOW PATTERNS

Natural flow regimes are important for sustaining riverine vegetation. The regulation of river flows to provide water for agriculture often results in changes to flow timing. This study assesses the impact of altered seasonal flow patterns on riverine flora. Within temperate Australia, we surveyed the vegetation of five lowland rivers, three of which have large dams that alter their seasonal flow patterns; the other two are unregulated. From four to six sites were selected on each river, and these were classified into three levels of regulation based on the extent to which the timing of their seasonal flow patterns were altered. Sites were surveyed in winter and the following summer. Permanent quadrats were also established at a number of the surveyed sites and resurveyed every 3 months. Of the 267 plant taxa identified, 145 were exotic (non‐native). More exotic taxa and fewer native taxa were associated with increasing level of seasonal flow inversion (regulation). In particular, greater numbers of short‐lived exotic terrestrial taxa and fewer native woody taxa were associated with increasing level of regulation. Some exotic woody species (e.g. willows) were more common in the unregulated rivers and may have life‐history traits favoured by the natural seasonal flow patterns of study area. Multivariate analyses showed that level of regulation had a significant effect on the overall composition of the riverine vegetation. Our results provide support for the hypotheses that flow regulation adversely affects native species diversity and increases the vulnerability of riparian zones to invasion by exotic species; however, these effects are dependent on plant species' life‐history strategies. Our study highlights the importance of natural seasonal flow patterns for sustaining native riverine plant communities. Flow management aimed at maintaining or restoring ecological values should consider seasonal flow patterns. Winter/spring flow peaks may be particularly important for the recruitment of native riverine plants, especially trees and shrubs, and reducing the extent of exotic annuals and grasses. Copyright © 2012 John Wiley & Sons, Ltd.     

蛤蒌叶提取物对口腔细菌和大肠杆菌的抑菌活性研究

目的刜步研究蛤蒌叶乙醇提取物及水提取物对口腔细菌和大肠杆菌的抑菌效果。方法采用平板打孔法测定不同乙醇浓度蛤蒌叶提取液对大肠杆菌的生长抑制活性,用比浊法测定不同提取条件蛤蒌叶提取液对口腔细菌的生长抑制活性。结果 60%、80%和100%乙醇蛤蒌叶提取液对大肠杆菌及对口腔菌生长均有明显抑制作用。在3个因素所设水平下对口腔细菌抑制效果适宜提取条件分别为:乙醇浓度为80%、提取温度为4℃、提取时间为20 h。当乙醇浓度为100%时,对大肠杆菌的抑制效果较好。结论蛤蒌叶乙醇提取液中含有抑制大肠杆菌和口腔细菌生长的活性次生物质,且在高浓度的乙醇溶液和低温条件下提取液抑制口腔细菌效果更佳。     

基于高通量测序分析虾夷扇贝柱菌群结构及腐败优势菌

为揭示虾夷扇贝柱的菌群结构及腐败优势菌,通过对宏基因组DNA进行高通量测序,分析虾夷扇贝柱新鲜和腐败样品的菌群结构,同时对可培养细菌菌群基因组DNA进行高通量测序,分析新鲜和腐败样品可培养细菌菌群的结构特征。结果表明,对宏基因组测序后获得的新鲜虾夷扇贝柱中细菌菌群多样性丰富,其中相对丰度较高的有Candidatus kuenenia（10.73%）、弧菌属（Vibrio,8.15%）、别弧菌属（Aliivibrio,7.38%）、芽孢杆菌属（Bacillus,7.20%）和未分类菌（unclassified,16.08%）;4?℃的腐败优势菌为发光杆菌属（Photobacterium,46.91%）、别弧菌属（36.82%）和假交替单胞菌属（Pseudoalteromonas,11.01%）,15?℃的腐败优势菌为发光杆菌属（46.97%）和别弧菌属（43.33%）,25?℃的腐败优势菌为发光杆菌属（41.94%）、别弧菌属（23.10%）、梭杆菌属（Fusobacterium,18.61%）和乳酸菌属（Lactobacillus,10.60%）。对可培养细菌菌群基因组测序后发现,新鲜样品可培养细菌菌群多样性大大降低,大部分为假交替单胞菌属（89.46%）,在25?℃腐败后,可培养的腐败优势菌为弧菌属（50.98%）、希瓦氏菌属（Shewanella,17.43%）和乳酸菌属（10.68%）。本研究揭示了虾夷扇贝柱新鲜及腐败样品的菌群结构特征及腐败优势菌,为进一步研究微生物对虾夷扇贝柱品质劣化的作用机制提供一定参考。     

益生菌剂调整肠道疾病人群菌群结构丰度水平的研究

为探究益生菌剂对肠道疾病人群菌群多样性及丰度水平的调节能力。本研究以健康、便秘、腹泻及腹胀、 肠易激综合征患者、排便不规律等人群为对象,使其定时、定量摄入益生菌剂（probotic preparations,PPrs）共6 周, 采集新鲜粪便样品并提取DNA,利用Ion Torrent PGM测序技术进行16S rRNA V3区扩增子测序,并联合生物信息学 和多变量统计学分析方法对测序数据进行多样性分析。在测序深度满足要求的情况下,从门、科、属乃至种4 个水 平由浅至深挖掘益生菌剂对各受试人群肠道菌群失调的调节作用。所有测序序列在97%相似水平划分得到2 320 个 分类操作单元,拟杆菌门（Bacteroidetes）、硬壁菌门（Firmicutes）、变形菌门（Proteobacteria）、放线菌门 （Actinobacteria）为各组的优势菌门,占总序列数的99.81%。益生菌剂对各组受试人群的共性特征是：毛螺菌科 （Lachnospiraceae）的调整均有长期的积极作用,而产碱杆菌科（Alcaligenaceae）、理研菌科（Rikenellaceae）、 双歧杆菌科（Bifidobacteriaceae）等优势菌科在干预停止后又恢复至干预前的状态。益生菌剂对各种疾病状态人 群的作用存在差异,便秘组的蓝细菌门（Cyanobacteria）和梭杆菌门（Fusobacteria）均从无到有。经主成分分 析（principal component analysis,PCA）鉴定显示,在干预第1～4周期间,益生菌剂对腹泻组属水平的调整优于 其他两组,柔嫩梭菌属（Faecalibacterium）、不动杆菌属（Acinetobacter）、布劳特氏菌属（Blautia）、梭菌属 （Clostridium）、小类杆菌属（Dialister）、埃格特菌属（Eggerthella）、颗粒链菌属（Granulicatella）、乳杆菌属 （Lactobacillus）、草酸杆菌属（Oxalobacter）、Pyramidobacter等10 个属多样性及相对丰度均有明显的提升;便 秘组仅有普氏菌属（Prevotella）、巨单胞菌属（Megamonas）、柯林斯菌属（Collinsella）3 个属相对丰度变化; 其他组的Adlercreutzia、Collinsella、克雷白氏杆菌属（Klebsiella）、Parabacteroides、萨特氏菌属（Sutterella）5 个 属有相对丰度的变化。PCA分析还揭示了益生菌剂在不同肠道疾病个体菌群结构的调整方面存在明显的差异,对不 同肠道疾病的改善及治疗作用也不一样。另外,便秘组的Bacteroides和Odoribacter有降低的趋势,且回复到与对照 组接近的状态。经热图分析鉴定发现,Akkermansia muciniphila、Bacteroides fragilis、Faecalibacterium prausnitzii等 几种已被认定功效的关键菌阶段性地出现,但是停止干预后即消失,原有的Bacteroides ovatus开始降低,这些菌的 出现对维护宿主健康具有价值。综上所述,该益生菌剂干预能起到改变肠道微生物多样性的功效,并具有调整菌群 丰度水平的作用,表现出了抑制肠道有害微生物生长的作用,特别是对肠道健康有益菌的出现更体现出该益生菌剂 的生理功效;因此,该益生菌剂应用于维持肠道菌群结构的稳态具有广阔的市场前景。     

Microscopic investigation of palyno‐morphological features of melliferous flora of Lakki Marwat district,Khyber Pakhtunkhwa,Pakistan

The present study was carried out to investigate the polliniferous bee flora of Lakki Marwat district, Khyber Pakhtunkhwa, Pakistan. A total of 18 species, belonging to 13 different families were identified for the foraging activities of honeybees, namely, Cenchrus biflorus, Cestrum nocturnum, Citrus limon, Combretum indicum, Datura innoxia, Duranta erecta, Hamelia patens, Helianthus annuus, Ipomoea cairica, Luffa aegyptiaca, Nerium oleander, Ocimum basilicum, Parthenium hysterophorus, Pennisetum typhoides, Prosopis cineraria, Prosopis juliflora, Saccharum spontaneum, and Ziziphus jujuba. The identified melliferous flora was collected for the morpho‐palynological investigation. Pollen were acetolyzed, measured, and described qualitatively using light microscopy. The pollen types varied from psilate to echinate and colpi from tricolpate to hexacolpate. Quantitative characteristics including polar diameter, equatorial diameter, polar to equatorial ratio, colpi length, colpi width, spine length, spine width, and exine thickness of the pollen were determined and analyzed statistically using software IBM SPSS Statistics 20. The results of the present study highlighted the significance of pollen morphology of the bee flora of the area which may lead to the identification of the potential and useful botanical sources for beekeepers and to check the honey quality marketed from the study area.     

烤烟连作土壤环境中的障碍因子研究综述

从根系分泌物的自毒作用、土壤化学性状恶化、土壤微生物区系改变和土壤酶活性下降等方面综述了近年来烤烟连作土壤环境中障碍因子的研究结果,并对该领域今后的研究方向提出了展望。      

生物菌接地降阻技术在高土壤电阻率地段的应用

介绍应用生物菌接地降阻技术对高土壤电阻率地段高压输电线路杆塔接地工程的改造,以及几种接地方式接地电阻的计算方法。     

Screening of potential aquatic probiotics from the major microflora of guppies (Poecilia reticulata)

The fish (Poecilia reticulata) was used as the source for probiotics. 46 bacterial isolates were obtained from the skin, gills, guts and intestines of the guppy, Poecilia reticulata (collected from a government model fish farm in Kottayam, India). Of the above isolated strains, four isolates were selected based on their inhibitory spectrum against five indicator strains, Aeromonas hydrophila 1739, Vibrio cholerae 3906, Flavobacterium 2495, Acinetobacter 1271 and Alcaligenes 1424 (standard cultures collected from Microbial Type Culture Collection (MTCC) Chandigarh, India). Among the resulting isolates, two were gram-positive cocci, namely MBTU-PB2 and MBTU-PB3 and belong to the genus Staphylococcus. The other two were gram-negative rods, namely MBTU-PB1 and MBTU-PB4, of the genera Enterobacter and Acinetobacter, respectively. The basic probiotic characteristics of these isolates such as the production of bacteriocin like inhibitory substances (BLIS), antibiotic sensitivities and growth profiles were also determined. The above four isolated strains exhibited different antagonisms than the five indicator strains. During incubation, the antibacterial activity gradually increased in the inhibition zone and was influenced by the lag period (λ) and doubling time. The lag periods for most of the four selected strains were shorter than those of the indicator strains and the isolates had different growth rates (μ) than the indicator strains. All four isolates produced BLIS, however, the strains had different BLIS activities against the indicator strains. Treatment of the neutralized cell free supernatants of the selected isolates with proteases eliminated or reduced the BLIS activity, suggesting a proteinaceous nature of the inhibitory compounds. Further, the optimum BLIS activity was observed at neutral pH after 18 h of incubation. The antibiotic sensitivity assay revealed that the isolates were susceptible to routinely used antibiotics, whereas the plasmid profiles showed that the plasmids had no role in the antagonistic properties of the four isolated strains. The results showed that the isolates could be a promising source for biocontrol agents in aquacultures.