scholarly journals Determination of the relationship between epiphytes and selected filamentous bacteria in activated sludge

2016 ◽  
Author(s):  
◽  
Thobela Conco
Keyword(s):  
Electron Microscopy ◽  
Activated Sludge ◽  
Morphological Characteristics ◽  
Cell Interaction ◽  
Vital Role ◽  
Microbial Consortia ◽  
Filamentous Bacteria ◽  
Intrinsic Nature ◽  
Structural Support ◽  
Filamentous Cell

Activated sludge (AS) flocs are paramount in biological treatment of wastewater, are comprised of microbial consortia with organic and inorganic material bound together by extra polymeric substances (EPS). The filamentous bacteria play a vital role in the floc formation process by providing the necessary structural support. Presence of epiphytic attachment on selected filamentous bacteria is a commonly occurring phenomenon in activated sludge samples. Different theories have been proposed to describe this phenomenon; however, not much research has been carried out to explore the profundity of the attachment. In this study, an attempt has been made to elucidate the intrinsic nature of the epiphytic attachment between the bacterial rods and filamentous bacteria based on microscopic (morphological and structural) analysis. Characterization of these epiphytes were performed using fluorescence in situ hybridization (FISH) at group level using Alpha, Beta and Gamma Proteo-bacterial probes. Morphological characteristics of filament hosts and the bacterial rods at the interface region was assessed using scanning electron microscopy (SEM). The SEM micrographs indicated that the attachment was facilitated by more than the EPS layer. Further ultrastructural examination using transmission electron microscopy (TEM) indicated a possible cell-to-cell interaction between epiphytes and the selected filaments. Fibrillar structures resembling amyloid-like proteins were observed within the filament cell targeted by the epiphytes. An interaction was apparent between the amyloid like proteins and the epiphytes as exhibited by the direction of fibrillar structures pointing towards the approaching epiphytes. Common bacterial appendages such as pili and fimbria were absent at the interface and further noted was the presence of cell membrane extensions on the epiphytic bacteria protruding towards the targeted filamentous cell. The sheath of host filaments however, remained intact and unpenetrated, during colonization. Amyloid-like fibrils at interface may potentially play the role of attachment sites for the attaching epiphytes, as attachment facilitating appendages were not visualized.

scholarly journals Molecular characterization of filamentous bacteria isolated from full-scale activated sludge processes

2007 ◽  
Author(s):  
◽  
Zinhle Marrengane
Keyword(s):  
Activated Sludge ◽  
Morphological Characteristics ◽  
Molecular Techniques ◽  
Support Network ◽  
Bulk Liquid ◽  
Bacterial Cells ◽  
Filamentous Bacteria ◽  
Vast Number ◽  
Sludge Flocs ◽  
Activated Sludge Processes

Activated sludge flocs are responsible for flocculation, settling and dewaterability. It is important to maintain the growth off loc-forming bacteria for efficient sludge settleability and compaction for good quality effluent. Filamentous bacteria on the other hand are believed to provide rigid support network or backbone upon which floc-forming bacteria adhere to form stable activated sludge flocs (Wilderer et al., 2002; Ramothokang et al., 2003). Filamentous bacteria can also be detrimental to the process when they outgrow floc-forming bacteria. Morphologically filamentous bacteria are at an advantage as they have higher outward growth velocity and can extend freely to bulk liquid substrate. Proliferation of filamentous bacteria causes foaming and bulking (Martins et al., 2004). Although chemical alleviation measures to circumvent bulking are present, they are symptomatic (Chang et al., 2004). Eikelboom (1975) developed the first identification keys for the classification of filamentous bacteria that is primarily based on morphological characteristics and microscopic examination. Although very useful, this type of identification has its limitations. For instance some filamentous bacteria can change morphology in response to changes in the environment and although some of them can be morphologically similar they may vary considerably in their physiology and taxonomy (Martins et al., 2004). A vast number of filamentous bacteria are still very poorly understood which could be due to the problems of cultivation due to their slow growing nature and maintenance of cultures (Rossetti et al., 2006). This limitation necessitates a molecular approach to resolve the taxonomy of filamentous bacteria as it is a culture-independent technique which is highly accurate. This project was undertaken to verify the identity of pure cultures of filamentous bacteria isolated previously through the application of molecular techniques. The 16S rDNA are conserved regions in bacterial cells and they can be extracted and specific nucleic acid fragments amplified. Denaturation gradient gel electrophoresis enabled the separation of fragments of identical length but different size and served as an indication of purity (Muyzer et al., 1993).

Aberrant Type C Virus Production in a Cell Line Derived from Balb/3T3

1972 ◽  
Vol 30 ◽  
pp. 286-287
Author(s):  
N. Savage ◽  
A. Hackett
Keyword(s):  
Electron Microscopy ◽  
Cell Line ◽  
Leukemia Virus ◽  
Morphological Characteristics ◽  
Virus Production ◽  
Oncogenic Viruses ◽  
Endogenous Virus ◽  
Virus Particles ◽  
Moloney Leukemia Virus ◽  
A Cell

A cell line, UC1-B, which was derived from Balb/3T3 cells, maintains the same morphological characteristics of the non-transformed parental culture, and shows no evidence of spontaneous virus production. Survey by electron microscopy shows that the cell line consists of spindle-shaped cells with no unusual features and no endogenous virus particles.UC1-B cells respond to Moloney leukemia virus (MLV) infection by a change in morphology and growth pattern which is typical of cells transformed by sarcoma virus. Electron microscopy shows that the cells are now variable in shape (rounded, rhomboid, and spindle), and each cell type has some microvilli. Virtually all (90%) of the cells show virus particles developing at the cell surface and within the cytoplasm. Maturing viruses, typical of the oncogenic viruses, are found along with atypical tubular forms in the same cell.

Role of Glycogen as an Intracellular Carbon Reserve of Activated Sludge in the Competitive Growth of Filamentous and Non-Filamentous Bacteria

1991 ◽  
Vol 23 (4-6) ◽  
pp. 899-905 ◽  
Author(s):  
Y. Matsuzawa ◽  
T. Mino
Keyword(s):  
Activated Sludge ◽  
Feeding Pattern ◽  
Filamentous Bacteria ◽  
Competitive Growth ◽  
Maximum Capacity ◽  
Intermittent Feeding ◽  
Feeding Type ◽  
Continuous Feeding ◽  
The Relationship

Activated sludge mixed cultures were cultivated with a glucose containing substrate in order to investigate the relationship between the feeding pattern (continuous or intermittent feeding) and the glycogen reservation capacity of activated sludge. An experimental method to measure the maximum capacity of glycogen reservation in the sludge was developed. Sludge with higher glycogen reservation capacity has an ability to synthesize glycogen faster, which ensures the higher glucose uptake. Therefore, sludge which has high glycogen reservation capacity becomes predominant in intermittently fed reactors. When the feeding pattern was changed from continuous feeding to intermittent feeding, a filamentous bacterium, Type 1701, started to decrease and a gram positive tetrad coccus became predominant. When the feeding pattern was returned to continuous feeding, Type 1701 re-appeared. Type 1701 has lower glycogen reservation capacity than the tetrad coccus. Therefore, the former cannot dominate over the latter in intermittently fed reactors.

scholarly journals Acinetobacter tandoii ZM06 Assists Glutamicibacter nicotianae ZM05 in Resisting Cadmium Pressure to Preserve Dipropyl Phthalate Biodegradation

2021 ◽  
Vol 9 (7) ◽  
pp. 1417
Author(s):  
Xuejun Wang ◽  
Si Shen ◽  
Hao Wu ◽  
Haixia Wang ◽  
Lvjing Wang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Heavy Metals ◽  
Microbial Consortia ◽  
Environmental Media ◽  
Degrading Bacterium ◽  
Coculture System ◽  
Heavy Metals Contamination ◽  
Metabolite Inhibition ◽  
Comparative Transcriptomic Analysis ◽  
Scanning Electron

Dipropyl phthalate (DPrP) coexists with cadmium as cocontaminants in environmental media. A coculture system including the DPrP-degrading bacterium Glutamicibacter nicotianae ZM05 and the nondegrading bacterium Acinetobacter tandoii ZM06 was artificially established to degrade DPrP under Cd(II) stress. Strain ZM06 relieved the pressure of cadmium on strain ZM05 and accelerated DPrP degradation in the following three ways: first, strain ZM06 adsorbed Cd(II) on the cell surface (as observed by scanning electron microscopy) to decrease the concentration of Cd(II) in the coculture system; second, the downstream metabolites of ZM05 were utilized by strain ZM06 to reduce metabolite inhibition; and third, strain ZM06 supplied amino acids and fatty acids to strain ZM05 to relieve stress during DPrP degradation, which was demonstrated by comparative transcriptomic analysis. This study provides an elementary understanding of how microbial consortia improve the degradation efficiency of organic pollutants under heavy metals contamination.

scholarly journals A Thermally Conductive Pt/AAO Catalyst for Hydrogen Passive Autocatalytic Recombination

Catalysts ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 491
Author(s):  
Alina E. Kozhukhova ◽  
Stephanus P. du Preez ◽  
Aleksander A. Malakhov ◽  
Dmitri G. Bessarabov
Keyword(s):  
Electron Microscopy ◽  
Particle Size ◽  
Combustion Temperature ◽  
Volume Fraction ◽  
Morphological Characteristics ◽  
Al Alloy ◽  
Impregnation Method ◽  
Case Scenario ◽  
Worst Case ◽  
Thermal Distribution

In this study, a Pt/anodized aluminum oxide (AAO) catalyst was prepared by the anodization of an Al alloy (Al6082, 97.5% Al), followed by the incorporation of Pt via an incipient wet impregnation method. Then, the Pt/AAO catalyst was evaluated for autocatalytic hydrogen recombination. The Pt/AAO catalyst’s morphological characteristics were determined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The average Pt particle size was determined to be 3.0 ± 0.6 nm. This Pt/AAO catalyst was tested for the combustion of lean hydrogen (0.5–4 vol% H2 in the air) in a recombiner section testing station. The thermal distribution throughout the catalytic surface was investigated at 3 vol% hydrogen (H2) using an infrared camera. The Al/AAO system had a high thermal conductivity, which prevents the formation of hotspots (areas where localized surface temperature is higher than an average temperature across the entire catalyst surface). In turn, the Pt stability was enhanced during catalytic hydrogen combustion (CHC). A temperature gradient over 70 mm of the Pt/AAO catalyst was 23 °C and 42 °C for catalysts with uniform and nonuniform (worst-case scenario) Pt distributions. The commercial computational fluid dynamics (CFD) code STAR-CCM+ was used to compare the experimentally observed and numerically simulated thermal distribution of the Pt/AAO catalyst. The effect of the initial H2 volume fraction on the combustion temperature and conversion of H2 was investigated. The activation energy for CHC on the Pt/AAO catalyst was 19.2 kJ/mol. Prolonged CHC was performed to assess the durability (reactive metal stability and catalytic activity) of the Pt/AAO catalyst. A stable combustion temperature of 162.8 ± 8.0 °C was maintained over 530 h of CHC. To confirm that Pt aggregation was avoided, the Pt particle size and distribution were determined by TEM before and after prolonged CHC.

scholarly journals Green Synthesis and Incorporation of Sericin Silver Nanoclusters into Electrospun Ultrafine Cellulose Acetate Fibers for Anti-Bacterial Applications

Polymers ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1411
Author(s):  
Mujahid Mehdi ◽  
Huihui Qiu ◽  
Bing Dai ◽  
Raja Fahad Qureshi ◽  
Sadam Hussain ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Green Synthesis ◽  
Cellulose Acetate ◽  
Antibacterial Properties ◽  
Vital Role ◽  
Silver Nanoclusters ◽  
Composite Fibers ◽  
E Coli ◽  
Antibacterial Performance ◽  
Field Emission Electron Microscopy

Fiber based antibacterial materials have gained an enormous attraction for the researchers in these days. In this study, a novel Sericin Encapsulated Silver Nanoclusters (sericin-AgNCs) were synthesized through single pot and green synthesis route. Subsequently these sericin-AgNCs were incorporated into ultrafine electrospun cellulose acetate (CA) fibers for assessing the antibacterial performance. The physicochemical properties of sericin-AgNCs/CA composite fibers were investigated by transmission electron microscopy (TEM), field emission electron microscopy (FE-SEM), Fourier transform infrared spectroscopy (FTIR) and wide X-ray diffraction (XRD). The antibacterial properties of sericin-AgNCs/CA composite fibers against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) were systematically evaluated. The results showed that sericin-AgNCs incorporated in ultrafine CA fibers have played a vital role for antibacterial activity. An amount of 0.17 mg/mL sericin-AgNCs to CA fibers showed more than 90% results and elevated upto >99.9% with 1.7 mg/mL of sericin-AgNCs against E. coli. The study indicated that sericin-AgNCs/CA composite confirms an enhanced antibacterial efficiency, which could be used as a promising antibacterial product.

scholarly journals Deep learning-based morphology classification of activated sludge flocs in wastewater treatment plants

2021 ◽  
Author(s):  
Hisashi Satoh ◽  
Yukari Kashimoto ◽  
Naoki Takahashi ◽  
Takashi Tsujimura
Keyword(s):  
Wastewater Treatment ◽  
Deep Learning ◽  
Activated Sludge ◽  
Morphological Change ◽  
Wastewater Treatment Plants ◽  
Filamentous Bacteria ◽  
Sludge Flocs

A deep learning-based two-label classifier 1 recognized a 20% morphological change in the activated flocs. Classifier-2 quantitatively recognized an abundance of filamentous bacteria in activated flocs.

The Role of Microscopy in Preclinical Safety Assessment

2000 ◽  
Vol 6 (S2) ◽  
pp. 998-999
Author(s):  
Barbara J. Dovey-Hartman
Keyword(s):  
Electron Microscopy ◽  
Vital Role ◽  
Pathology Report ◽  
Clinical Phase ◽  
Transmission Electron ◽  
New Chemical Entities ◽  
Regulatory Submissions ◽  
Hematoxylin And Eosin ◽  
Preclinical Safety

Microscopy plays a vital role in assessing the safety of New Chemical Entities (NCE) in the pre-clinical phase of drug development. Light microscopy (LM), transmission electron microscopy (TEM) and scanning electron microscopy (SEM) are used at the Schering-Plough Research Institute (SPRI) for evaluation of NCE. To support regulatory submissions, NCE are routinely tested in rodents in short-term studies such as one-month toxicity studies, and in longterm studies such as oncogenicity studies that may last 24 months. At the completion of a study, the animals are necropsied and the required tissues collected and stored in fixative. The tissues for LM are processed to slides and stained with Hematoxylin and Eosin (H&E). The information derived from the examination of these tissues by LM becomes an essential part of the pathology report. The LM examination of these tissues usually yields the information needed to either progress a NCE or otherwise deter or halt development.

scholarly journals Effects of mechanical tension on protrusive activity and microfilament and intermediate filament organization in an epidermal epithelium moving in culture.

1986 ◽  
Vol 102 (4) ◽  
pp. 1400-1411 ◽  
Author(s):  
J Kolega
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Intermediate Filaments ◽  
Intermediate Filament ◽  
Mechanical Tension ◽  
Cytoskeletal Organization ◽  
Structural Support ◽  
Transmission Electron ◽  
Locomotive Activity ◽  
Filament Surface

Mechanical tension influences tissue morphogenesis and the synthetic, mitotic, and motile behavior of cells. To determine the effects of tension on epithelial motility and cytoskeletal organization, small, motile clusters of epidermal cells were artificially extended with a micromanipulated needle. Protrusive activity perpendicular to the axis of tension was dramatically suppressed. To determine the ultrastructural basis for this phenomenon, cells whose exact locomotive behavior was recorded cinemicrographically were examined by transmission electron microscopy. In untensed, forward-moving lamellar protrusions, microfilaments appear disorganized and anisotropically oriented. But in cytoplasm held under tension by micromanipulation or by the locomotive activity of other cells within the epithelium, microfilaments are aligned parallel to the tension. In non-spreading regions of the epithelial margin, microfilaments lie in tight bundles parallel to apparent lines of tension. Thus, it appears that tension causes alignment of microfilaments. In contrast, intermediate filaments are excluded from motile protrusions, being confined to the thicker, more central part of the cell. They roughly follow the contours of the cell, but are not aligned relative to tension even when microfilaments in the same cell are. This suggests that the organization of intermediate filaments is relatively resistant to physical distortion and the intermediate filaments may act as passive structural support within the cell. The alignment of microfilaments under tension suggests a mechanism by which tension suppresses protrusive activity: microfilaments aligned by forces exerted through filament-surface or filament-filament interconnections cannot reorient against such force and so cannot easily extend protrusions in directions not parallel to tension.

Validation of a new image analysis procedure for quantifying filamentous bacteria in activated sludge

2014 ◽  
Vol 70 (6) ◽  
pp. 955-963 ◽  
Author(s):  
Ewa Liwarska-Bizukojc ◽  
Marcin Bizukojc ◽  
Olga Andrzejczak
Keyword(s):  
Image Processing ◽  
Image Analysis ◽  
Activated Sludge ◽  
Analysis Procedure ◽  
Automated Image Analysis ◽  
Filamentous Bacteria ◽  
Image Processing And Analysis ◽  
Manual Counting ◽  
Analysis Application ◽  
Activated Sludge Systems

Quantification of filamentous bacteria in activated sludge systems can be made by manual counting under a microscope or by the application of various automated image analysis procedures. The latter has been significantly developed in the last two decades. In this work a new method based upon automated image analysis techniques was elaborated and presented. It consisted of three stages: (a) Neisser staining, (b) grabbing of microscopic images, and (c) digital image processing and analysis. This automated image analysis procedure possessed the features of novelty. It simultaneously delivered data about aggregates and filaments in an individual calculation routine, which is seldom met in the procedures described in the literature so far. What is more important, the macroprogram performing image processing and calculation of morphological parameters was written in the same software which was used for grabbing of images. Previously published procedures required using two different types of software, one for image grabbing and another one for image processing and analysis. Application of this new procedure for the quantification of filamentous bacteria in the full-scale as well as laboratory activated sludge systems proved that it was simple, fast and delivered reliable results.

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