Involvement of oxidative stress and growth at high cell density in the viable but nonculturable state of Photorhabdus temperata ssp. temperata strain K122

Jallouli, Wafa; Zouari, Nabil; Jaoua, Samir

doi:10.1016/j.procbio.2010.01.007

Cited by 26 publications

(15 citation statements)

References 33 publications

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“…1b). As expected, independently on the supplemented sodium chloride concentration, cell culturability was not affected and 92-95.6% of counted cells were able to form colonies on solid medium containing sodium pyruvate or catalase as an anti-reactive oxygen species (ROS) agent [14]. In addition, oral toxicity of the produced cells against E. kuehniella larvae was improved beyond 2 g/l NaCl, which showed that sodium chloride enhanced P. temperata growth and biological activity (Fig.…”

Section: Resultssupporting

confidence: 70%

“…3b). As expected, using catalase at 2,000 units/ml or 40 mg sodium pyruvate per plate in the solid medium allowed 100% of cells counted microscopically to form colonies [14]. Grown in the complex medium, P. temperata cells exhibited higher toxicity since growth inhibition of the E. kuehniella larvae was improved significantly and reached 9.82% exhibited by 1 9 10 8 cells/ml after 48 h of incubation at 30°C instead of 6.5% growth inhibition obtained in the optimized medium (Fig.…”

Section: Substitution Of Glucose and Yeast Extract By Soya Bean Mealsupporting

confidence: 72%

“…Stability of CFU counts until 78 h of incubation after plating cells on LB agar could be justified by the fact that in the new formulated medium, growth occurred at low cell density of 12 9 10 8 cells/ml. We have previously shown that growth at low cell density avoided the enhancement of VBNC state after 24 h of incubation [14]. In addition, in the complex medium, Vsm polymorphism identified in P. temperata strain K122 [8] was completely overcome even after prolonged incubation, which is interesting from a practical point of view for the production of highly active bioinsecticides, because such forms are less toxic to E. kuehniella larvae.…”

Section: Discussionmentioning

confidence: 88%

“…As much as 100 ll from each appropriate dilution of the culture sample, giving 30-120 colonies, was plated on LB medium or/and LB medium containing 2,000 units/ml catalase or 40 mg sodium pyruvate, to enhance the recovery of P. temperata cells at the viable, but nonculturable (VBNC) state [14], then incubated at 30°C during 48 h. Incubation was prolonged up to 72 h for detection of white, red and yellow colonies. Each type of colony was numbered as they can be easily identified by shape and color.…”

Section: Culturable Cell Countsmentioning

confidence: 99%

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Overcoming the production limitations of Photorhabdus temperata ssp. temperata strain K122 bioinsecticides in low-cost medium

Jallouli

Jaoua

Zouari

2011

Bioprocess Biosyst Eng

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For low-cost production of Photorhabdus temperata ssp. temperata strain K122 bioinsecticide, a cheap complex medium was optimized. Diluted seawater was used as the source of micronutrients, especially sodium chloride, involved in the improvement of cell density, culturability and oral toxicity of the bacterium P. temperata against Ephestia kuehniella larvae. Thus, the new formulated medium was composed only of 10 g/l of soya bean meal, used as the carbon and nitrogen main source, mixed in sevenfold diluted seawater. At such conditions, several limitations of P. temperata bioinsecticide productions were shown to be overcome. The appearance of variants small colony polymorphism was completely avoided. Thus, the strain K122 was maintained at the primary form even after prolonged incubation. Moreover, the viable but nonculturable state was partially overcome, since the ability of P. temperata cells to form colonies on the solid medium was prolonged until 78 h of incubation. In addition, when cultured in the complex medium, P. temperata cells were produced at high cell density of 12 × 10(8) cells/ml and exhibited 81.48% improvement of oral toxicity compared to those produced in the optimized medium. With such medium, the large-scale bioinsecticides production into 3-l fully controlled fermenter improved the total cell counts, CFU counts and oral toxicity by 20, 5.81 and 16.73%, respectively. This should contribute to a significant reduction of production cost of highly potent P. temperata strain K122 cells, useful as a bioinsecticide.

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Section: Resultssupporting

confidence: 70%

Section: Substitution Of Glucose and Yeast Extract By Soya Bean Mealsupporting

confidence: 72%

Section: Discussionmentioning

confidence: 88%

Section: Culturable Cell Countsmentioning

confidence: 99%

See 2 more Smart Citations

Overcoming the production limitations of Photorhabdus temperata ssp. temperata strain K122 bioinsecticides in low-cost medium

Jallouli

Jaoua

Zouari

2011

Bioprocess Biosyst Eng

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“…The gut and the fat body were homogenized in PBS using a hand-held Potter homogenizer. To determine the number of recoverable bacteria, serial dilutions of tissue homogenates were prepared with PBS and plated onto LB agar and LB agar supplemented with catalase at 2000 Units/plate to enhance the recovery of P. temperata K122 in the VBNC state (Jallouli et al, 2010).…”

Section: Bacterial Colonizationmentioning

confidence: 99%

Potential of Photorhabdus temperata K122 bioinsecticide in protecting wheat flour against Ephestia kuehniella

Jallouli

Abdelkefi-Mesrati

Tounsi

et al. 2013

Journal of Stored Products Research

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Improvement of Photorhabdus temperata bioinsecticides production in low‐cost media through adequate fermentation technology

Jallouli¹,

Jaoua²,

Zouari³

2012

Biotechnology Progress

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To develop a cost effective process for bioinsecticides production by Photorhabdus temperata, dissolved oxygen (DO) requirements were investigated in both the complex and the optimized media using diluted seawater as a source of micronutrients. By varying DO concentrations, tolerance to hydrogen peroxide was shown to be medium dependant. Indeed, P. temperata cells grown in the complex medium, exhibited higher tolerance than cells grown in the optimized medium (OM). Tolerance to H(2)O(2) was shown to be related to intracellular reactive oxygen species (ROS) accumulation during soya bean meal or glucose assimilation, as shown by flow cytometry analysis. To avoid oxidative stress damages in P. temperata cells cultured in the OM, DO concentration should be constant 50% saturation throughout the fermentation. However, a DO-shift control strategy was demonstrated to be beneficial for P. temperata bioinsecticide production in the complex medium. By using such a strategy biomass, culturability, and oral toxicity reached 16.5 × 10(8), 1.15 × 10(8) cells/mL and 64.2%, respectively, thus was 16.19, 26.37, and 12.2% more than in the cultures carried out at a constant 50% saturation.

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Involvement of oxidative stress and growth at high cell density in the viable but nonculturable state of Photorhabdus temperata ssp. temperata strain K122

Cited by 26 publications

References 33 publications

Overcoming the production limitations of Photorhabdus temperata ssp. temperata strain K122 bioinsecticides in low-cost medium

Overcoming the production limitations of Photorhabdus temperata ssp. temperata strain K122 bioinsecticides in low-cost medium

Potential of Photorhabdus temperata K122 bioinsecticide in protecting wheat flour against Ephestia kuehniella

Improvement of Photorhabdus temperata bioinsecticides production in low‐cost media through adequate fermentation technology

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