Structure and microbial composition of nitrifying microbial aggregates and their relation to internal mass transfer effects

2004 ◽  
Vol 50 (10) ◽  
pp. 213-220 ◽  
Author(s):  
B.-M. Wilén ◽  
D. Gapes ◽  
L.L. Blackall ◽  
J. Keller
Keyword(s):  
Mass Transfer ◽  
In Situ Hybridisation ◽  
Gas Analysis ◽  
Microbial Consortia ◽  
Fish Analysis ◽  
Fluorescence In Situ Hybridisation ◽  
Internal Mass ◽  
Microbial Composition ◽  
Transfer Resistance ◽  
Internal Mass Transfer

This paper presents an analysis of the structure and microbial composition of nitrifying aggregates, formed as either flocs or granules, in sequencing batch reactors (SBR) operated with a high ammonium load. The structure and microbial community of the aggregates was determined by fluorescence in situ hybridisation (FISH). The aggregate structure and size was related to mass transfer limitations observed by measurements of OURs measured by either a titrimetric and off-gas analysis sensor (TOGA) or by microsensors. The FISH analysis showed that the spatial arrangement of the microbial consortia correlated well with the oxygen gradients inside the aggregates. In the larger aggregates, the ammoniumand nitrite-oxidising bacteria were mainly concentrated to the outer 100–200 μm, whereas in the floc system, the bacteria were distributed throughout the entire aggregate. This indicates that the internal mass transfer resistance is considerably larger when the aggregate size increases which is directly supported by TOGA measurements.

Use of macromolecular compounds to control internal mass transfer in a granular material

1982 ◽  
Vol 43 (6) ◽  
pp. 1389-1394
Author(s):  
A. M. Abramets ◽  
I. I. Lishtvan ◽  
N. V. Churaev
Keyword(s):  
Mass Transfer ◽  
Granular Material ◽  
Internal Mass ◽  
Internal Mass Transfer

scholarly journals Reliable cell and tissue morphology-based diagnosis of endemic Burkitt lymphoma in resource-constrained settings in Ghana

2019 ◽  
Author(s):  
Cecilia Smith-Togobo ◽  
Mette Ø Pedersen ◽  
Steffen G Jensen ◽  
Babatunde Duduyemi ◽  
Richard K Gyasi ◽  
...  
Keyword(s):  
Burkitt Lymphoma ◽  
In Situ Hybridisation ◽  
B Cell Lymphoma ◽  
Diagnostic Tools ◽  
Fish Analysis ◽  
Fluorescence In Situ Hybridisation ◽  
Morphological Examination ◽  
Pathology Laboratory ◽  
Retrospective Assessment ◽  
Laboratory Investigations

Abstract Endemic Burkitt lymphoma (eBL) is an aggressive B-cell lymphoma, which is a common childhood cancer in areas with intense transmission of Plasmodium falciparum parasites. Early and accurate diagnosis is a prerequisite for successful therapy, but it optimally involves advanced laboratory investigations. These are technologically demanding, expensive, and often difficult to implement in settings where eBL is prevalent. Diagnosis is thus generally based on clinical assessment and morphological examination of tumour biopsies or fine-needle aspirates (FNAs). The purpose of the present study was to assess the accuracy of eBL diagnosis at two tertiary hospitals in Ghana. To that end, we studied FNAs from 29 eBL patients and 21 non-eBL lymphoma patients originally diagnosed in 2018. In addition, we examined 111 archival formalin-fixed and paraffin-embedded (FFPE) biopsies from Ghanaian patients originally diagnosed as eBL (N=55) or non-eBL (N=56) between 2010 and 2017. Availability-based subsets of samples were subjected to haematoxylin-eosin or Giemsa staining, C-MYC immunohistochemistry, and fluorescence in situ hybridisation (FISH) analysis of c-myc rearrangements We found a good correlation between original diagnosis and subsequent retrospective assessment, particularly for FNA samples. However, evidence of intact c-myc genes and normal C-MYC expression in samples from some patients originally diagnosed as eBL indicates that morphological assessment alone can lead to eBL over-diagnosis in our study area. In addition, several FFPE samples could not be assessed retrospectively, due to poor sample quality. Therefore, the simpler FNA method of obtaining tumour material is preferable, particularly when careful processing of biopsy specimens cannot be guaranteed. We conclude that the accuracy of eBL diagnostic tools available in Ghana is generally adequate, but could be improved by implementation of additional pathology laboratory investigations. Improved attention to adequate preservation of archival samples is recommended.

Micro-environments and mass transfer phenomena in biofilms studied with microsensors

1999 ◽  
Vol 39 (7) ◽  
pp. 173-178 ◽  
Author(s):  
Dirk de Beer ◽  
Andreas Schramm
Keyword(s):  
Mass Transfer ◽  
Liquid Flow ◽  
Microbial Population ◽  
In Situ Hybridisation ◽  
Molecular Techniques ◽  
Complex Structures ◽  
Microbial Composition ◽  
Direct Observations ◽  
Direct Measurements

Direct observations on chemical micro-environment and microbial composition in biofilms are rare. The combination of microsensor and molecular techniques is highly useful for studies on the microbial ecology of biofilms. We shortly describe some applications of microsensors to study mass transfer phenomena and microbial processes in biofilms. It has recent been recognized that biofilms are not always flat layers of cells, but can consist of complex structures allowing liquid flow. Thus the classical view, that transport in biofilms is diffusional, is challenged. In laboratory grown biofilms the effect of convection on mass transfer was demonstrated. The microsensor technique has improved, so that direct in situ measurements in living biofilms are possible. By direct measurements of liquid flow with microsensors we show that in biofilms grown in bioreactors heterogeneity and convectional transport must also be taken into account. For the description of the microbial population we use molecular techniques, such as in situ hybridisation with 16S rRNA-targeted oligonucleotide probes. In a nitrifying-denitrifying biofilm we found a complex nitrifying community consisting of members of the genera Nitrosomonas, Nitrosospira, Nitrobacter and Nitrospira. Their occurrence was correlated with nitrification activity as determined by microsensor measurements.

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