Effects of glycerol on Pseudomonas fluorescens BTP1 freeze-dried

in International Journal of Biotechnology and Biochemistry. (2012), 8(2), 245-258

The storage stability of freeze-dried powders was studied by parameters such as loss of viability on the Plate Count Agar (PCA). Powder with glycerol (PG) contains 8.4x1010cfu/g before storage 1 ... [more ▼]

The storage stability of freeze-dried powders was studied by parameters such as loss of viability on the Plate Count Agar (PCA). Powder with glycerol (PG) contains 8.4x1010cfu/g before storage 1.1x1010cfug after 3 months at 4°C and 6.0x108cfu/g after 3 months at 20°C. The concentration of soluble proteins (mg/g) decrease during storage at 4°C from 3.77 to 0.80 after 90 days; and the ratios of unsaturated to saturated fatty acids (C18:3/C16:0 and C18:2/C16:0) decrease respectively from 0.05 to 0.04 and 0.007 to 0.004 after 3 months at 4°C. This ratio characterises the membrane fluidity. Powder without glycerol (PS) contains 1.1x1010 cfu/g before storage and 1.4 x 108 cfu/g after 3 months at 4°C and 1.4 x 107 cfu/g after 3 months at 20°C. The concentration of soluble proteins (mg/g) decrease during storage at 4°C from 4.08 to 0.42 after 90 days, the glutathione concentration decrease during storage at 4°C from 2.2 to 1.4. The beneficial effect of glycerol on fatty acid composition during freezedrying is shown and the ratios of unsaturated to saturated fatty acids (C18:2/C16:0 and C18:3/C16:0) decrease respectively from 0.019 to 0.004 and 0.054 to 0.036 after 90 days storage at 4°C. Analysis by flow cytometry was used to assess the physiological state in which cells are at the end of freeze-drying. We found 13.5% live cells, 36.1% dead cells and 50.4% cells in an intermediate state for powder with glycerol (PG) after freeze-drying. These results shows that glycerol play an important role in Pseudomonas fluorescens BTP1 desiccation during freeze-drying, by maintaining a degree of viability after freeze-drying and during storage. [less ▲]

Isolation of bioactive peptides from tryptone that modulate lipase production in Yarrowia lipolytica

in Bioresource Technology (2009), 100

Culture And Spray-Drying Of Tsukamurella Paurometabola C-924: Stability Of Formulated Powders

in Biotechnology Letters (2007), 29(11),

The nematocidal agent, Tsukamurella paurometabola C-924, was cultured in a 300 l bioreactor. Spray-dried formulations of this microorganism were prepared using sucrose. At an outlet temperature 628C ... [more ▼]

The nematocidal agent, Tsukamurella paurometabola C-924, was cultured in a 300 l bioreactor. Spray-dried formulations of this microorganism were prepared using sucrose. At an outlet temperature 628C, survival rates between 12 and 85% were reached with sucrose up to 10% (w/w). The stability study of the powders showed that the best storage condition was at 48C under vacuum. A new method for the calculation of cell death order for bacteria stored at low temperatures was developed. Powders stored under vacuum showed an Arrhenius behavior in relation to cell death kinetics. [less ▲]

Production and down-stream processing of an extracellular lipase from the yeast Yarrowia lipolytica

in Enzyme & Microbial Technology (2006), 38(6), 756-759

Lipase constitutes an interesting class of enzyme with many biotechnological applications. However, the development of a fruitful process must be set up to obtained a product compatible with the ... [more ▼]

Lipase constitutes an interesting class of enzyme with many biotechnological applications. However, the development of a fruitful process must be set up to obtained a product compatible with the industrial and commercial needs. Here, we report the development of such a process for the extracellular lipase secreted by the yeast Yarrowia lipolytica. The enzyme production, carried out in a 2000 L bioreactor, led to a lipase activity of approximately 1100 U mL(-1) after 53 h of fermentation. The post-culture treatment, consisting of a centrifugation, a filtration and an ultra-filtration steps, led to 15-fold volume reduction and a 8-fold increased of the lipase activity. Finally, addition of 12% of milk powder and 3% of gum arabic before spray-drying dehydration led to a stable powder with a lipolytic activity of 37,500 U g D.W.(-1). (c) 2005 Elsevier Inc. All rights reserved. [less ▲]

Microbial inoculation for improving the growth and health of micropropagated strawberry

in Applied Soil Ecology (2004), 27(3), 243-258

Multimicrobial inoculation has been proposed as a way of protecting plants against environmental stress and increasing the sustainability of plant production. To study these possibilities in a ... [more ▼]

Multimicrobial inoculation has been proposed as a way of protecting plants against environmental stress and increasing the sustainability of plant production. To study these possibilities in a micropropagation system, microplants of strawberry, Fragaria x ananssa, were inoculated or left uninoculated with five microorganisms (Glomus mosseae BEG29, Bacillus subtilis M3, Trichoderma harzianum DB11, Pseudomonas fluorescens C7rl2 and Gliocladium catenulatum Gliomix(R)), used either singly or in dual mixtures in the presence or absence of the strawberry diseases crown rot (Phytophthora cactorum) and red stele (P. fragariae). Finnish light Sphagnum peat was used as the growth substrate in the experiments. Seven experiments were performed as two to three months pot experiments in greenhouses of research laboratories in Finland and Belgium and in a nursery in Finland. In most experiments, the inoculated microorganims were detected at sufficient densities four weeks after inoculation. Exceptions were T harzianum and G. mosseae which were detected at insufficient densities in several experiments. This might have been due to the biological and/or nutritional properties of the peat. None of the microorganisms or their mixtures caused significant growth-promoting effects in more than two experiments. Dual inoculation did not increase growth more than inoculation with single organisms. B. subtilis was the most promising growth promoting microorganism. Most of the microbial treatments decreased crown rot shoot symptoms as well as the numbers of oospores in the roots when the experiment was performed in autumn. In the summer experiment with conditions more favourable for strawberry growth, no disease control was obtained, but some of the microorganisms increased the severity of crown rot. No microbial treatment decreased shoot symptoms of red stele, but the degree of root necrosis was slightly decreased by B. subtilis and G. mosseae + G. catenulatum. The numbers of oospores of P. fragariae in strawberry roots were not decreased by any treatment, but several treatments increased them. Both growth promotion and disease control considered, the single microorganisms T harzianum, G. catenulatum and B. subtilis as well as the mixture T harzianum + G. catenulatum were the most promising treatments in this study. However, the great variation between experiments indicates that more studies are needed for optimization of the whole plant-substrate-microorganism system. The importance of microbial inoculation for ensuring subsequent growth in the field also needs to be studied. (C) 2004 Elsevier B.V. All rights reserved. [less ▲]

An approach to desication-tolerant bacteria in starter culture production

in Engineering and manufacturing for biotechnology (2001)

Desiccation-tolerance : an advantage for the biotechnological applications of bacteria

Poster (1999, July)

Improving the catabolic functions in desiccation-tolerant soil bacteria in view of their use in bioaugmentation.

Poster (1998, May 08)

Effect Of Drying On Bioremediation Bacteria Properties

in Applied Biochemistry and Biotechnology (1998), 70-2

Effect of drying and long term conservation on bioremediation properties of Rhodococcus erythropolis

in Mededelingen van de Faculteit Landbouwkundige en Toegepaste Biologische Wetenschappen (Rijksuniversiteit te Gent) (1997), 62/4b