Looking for phosphate-accumulating bacteria in activated sludge processes: a multidisciplinary approach.

Over the past decades, an increasing need in renewable resources has progressively appeared. This trend concerns not only fossil fuels but also mineral resources. Wastewater and sewage sludge contain significant concentrations in phosphate and can be considered as a fertilizer source of the utmost importance.

Characterisation of Phosphate Accumulating Organisms and Techniques for Polyphosphate Detection: A Review.

Phosphate minerals have long been used for the production of phosphorus-based chemicals used in many economic sectors. However, these resources are not renewable and the natural phosphate stocks are decreasing. In this context, the research of new phosphate sources has become necessary.

Phenotypic variability in bioprocessing conditions can be tracked on the basis of on-line flow cytometry and fits to a scaling law.

Noise in gene and protein expression is a major cause for bioprocess deviation. However, this phenomenon has been only scarcely considered in real bioprocessing conditions. In this work, a scaling-law derived from genome-scale studies based on GFP reporter systems has been calibrated to an on-line flow cytometry device, allowing thus to get an insight at the level of promoter activity and associated noise during a whole microbial culture carried out in bioreactor.

Scale-down effect on the extracellular proteome of Escherichia coli: correlation with membrane permeability and modulation according to substrate heterogeneities.

Protein leakage is induced in well-mixed fed-batch bioreactor by comparison with cultures carried out in scale-down conditions. This effect is attributed to a progressive increase of cell membrane permeability and the synthesis of several outer-membrane components allowing to cope with substrate limitation commonly found in high cell density culture. A comparative analysis of protein leakage has thus been performed in well-mixed bioreactors and in scale-down devices.

Isolation of amylolytic, xylanolytic, and cellulolytic microorganisms extracted from the gut of the termite Reticulitermes santonensis by means of a micro-aerobic atmosphere.

The aim of this work was to isolate enzyme-producing microorganisms from the tract of the termite Reticulitermes santonensis. The microorganisms were extracted from the guts and anaerobic (CO₂ or CO₂/H₂) and micro-aerobic atmospheres were used to stimulate growth. Three different strategies were tried out.

A low-cost, multiplexable, automated flow cytometry procedure for the characterization of microbial stress dynamics in bioreactors.

Background: Microbial cell population heterogeneity is now recognized as a major source of issues in the development and optimization of bioprocesses. Even if single cell technologies are available for the study of microbial population heterogeneity, only a few of these methods are available in order to study the dynamics of segregation directly in bioreactors. In this context, specific interfaces have been developed in order to connect a flow cytometer directly to a bioreactor for automated analyses.

Isolation and cultivation of a xylanolytic Bacillus subtilis extracted from the gut of the termite Reticulitermes santonensis.

The aim of this work was the isolation of xylanolytic microorganisms from the digestive tract of the termite Reticulitermes santonensis. The reducing sugars released after the hydrolysis of xylans can be further fermented to provide bioethanol. A xylanolytic strain of Bacillus subtilis was isolated from the hindgut of the termite and displayed amylase and xylanase activities.

Real-time monitoring of cell viability and cell density on the basis of a three dimensional optical reflectance method (3D-ORM): investigation of the effect of sub-lethal and lethal injuries.

Cell density and cell viability have been followed on-line by using a three-dimensional optical reflectance method (3D-ORM) probe. This method has allowed to highlight the differences between a well-mixed and a scale-down bioreactor configured in order to reproduce mixing deficiencies during a fed-batch culture of Escherichia coli. These differences have been observed both for the obscuration factor (OBF) and the coincidence probability delivered by the probe.

Design of growth-dependent biosensors based on destabilized GFP for the detection of physiological behavior of Escherichia coli in heterogeneous bioreactors.

In this work, we present the design and characterization of Green Fluorescent Protein (GFP)-based reporter systems designed to describe cellular activity in "complex," heterogeneous bioreactors. The reporter systems consist of Escherichia coli strains carrying growth dependent promoters fused to genes expressing stable and unstable variants of GFP, respectively. The response of Escherichia coli cells to transient exposure to glucose was studied in a two-compartment scale down bioreactor (SDR) consisting of a well-stirred tank reactor (STR) connected to a plug-flow reactor (PFR).

Direct and indirect use of GFP whole cell biosensors for the assessment of bioprocess performances: design of milliliter scale-down bioreactors.

Substrate limitation responsive biosensors have been used for the development of a mini-bioreactor platform that can be used as a scale-down tool. Three green fluorescent protein (GFP) transcriptional reporters have been chosen in Escherichia coli, i.e.

(Trans)esterification of mannose catalyzed by lipase B from Candida antarctica in an improved reaction medium using co-solvents and molecular sieve.

Four co-solvents (dimethylformamide [DMF], formamide, dimethyl sulfoxide [DMSO], and pyridine) were tested with tert-butanol (tBut) to optimize the initial rate (v₀) and yield of mannosyl myristate synthesis by esterification catalyzed by immobilized lipase B from Candida antarctica. Ten percent by volume of DMSO resulted in the best improvement of v₀ and 48-hr yield (respectively 115% and 13% relative gain compared to pure tBut). Use of molecular sieve (5% w/v) enhances the 48-hr yield (55% in tBut/DMSO [9:1, v/v]).

Green fluorescent protein (GFP) leakage from microbial biosensors provides useful information for the evaluation of the scale-down effect.

Mixing deficiencies can be potentially detected by the use of a dedicated whole cell microbial biosensor. In this work, a csiE promoter induced under carbon-limited conditions was involved in the elaboration of such biosensor. The cisE biosensor exhibited interesting response after up and down-shift of the dilution rate in chemostat mode.