Kinetic Properties of a Novel Fusarium solani (phospho)lipase: A Monolayer Study

Using the monomolecular film technique, we studied interfacial properties of Fusarium solani lipase (FSL). This lipolytic enzyme was found to be unique among the fungal lipases possessing not only a lipase activity but also a high phospholipase one.The FSL was able to hydrolyze dicaprin films at various surface pressures. The surface pressure dependency, the stereospecificity, and the regioselectivity of FSL were performed using optically pure stereoisomers of diglyceride (1,2‐sn‐ dicaprin and 2,3‐sn‐dicaprin) and a prochiral isomer (1,3‐sn‐dicaprin) spread as monomolecular films at the air–water interface. The FSL prefers adjacent ester groups of the diglyceride isomers (1,2‐sn‐dicaprin and 2,3‐sn‐dicaprin) at low and high surface pressures. Furthermore, FSL was found to be markedly stereospecific for the sn‐1 position of the 1,2‐sn‐enantiomer of dicaprin at both low and high surface pressures.Moreover, FSL shows high activities on phospholipids monolayers. However, this enzyme displays high preference to zwitterionic phospholipids compared to the negatively charged ones. Chirality, 25:35‐38, 2012. © 2012 Wiley Periodicals, Inc.     

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

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 H₂O₂ 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 × 10⁸, 1.15 × 10⁸ 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. © 2012 American Institute of Chemical Engineers Biotechnol. Prog., 2012     

Functional characterization and FTIR-based 3D modeling of full length and truncated forms of Scorpio maurus venom phospholipase A2

Background

Heterodimeric phospholipase A₂ from venom glands of Tunisian scorpion Scorpio maurus (Sm-PLGV) had been purified. It contains long and short chains linked by a disulfide bridge. Sm-PLGV exhibits hemolytic activity towards human erythrocytes and interacts with phospholipid monolayers at high surface pressure. The investigation of structure-function relationships should provide new clues to understand its activity.

Cryptorchidie: influence sur la fertilité de l’âge au moment de l’orchidopexie, du siège et de la taille du testicule et de l’existence d’anomalies épididymaires

Despite surgical treatment, cryptorchidism is the most common cause of infertility. Through a literature review, the authors report current data on the influence of age at the time of orchidopexy, testicular size, the position of the testis, and the existence of epididymal anomalies on fertility.     

Intérêt de l’abaissement du testicule non descendu chez l’adulte. Etude à propos de 259 patients

Introduction

Undescended testis is a frequent congenital disease, more often diagnosed and treated during childhood. However, due to ignorance or negligence, this disease can be seen even after puberty, when it raises a therapeutic problem: is orchidopexy still useful? This study was designed to evaluate the outcome of orchidopexy at adulthood in terms of improvement of fertility and prevention of malignant degeneration.

Material and methods

Retrospective study performed over a 23-year period (1983–2005). We have found 259 patients with undescended testis diagnosed and treated after the age of 18 years.

Results

The mean age of patients was 24 years (range: 18–63). In the majority of cases, undescended testis was diagnosed at a systemic medical examination in 199 patients (77% of cases), and in a context of infertility in 33 patients, testicular malignancy in 8 patients, testicular torsion in 2 patients and, in 17 cases, undescended testis had been known since birth but was neglected by the parents. Undescended testis was unilateral in 209 cases and bilateral in 50 cases. Out of 37 couples, only 4 gave birth to children (10.8% paternity rate). Sperm analysis was abnormal in all infertile patients. All patients were treated by orchidopexy, except for 36 patients in whom orchidectomy was performed due to testicular atrophy (27 cases), malignancy (8 cases) or necrosis (1 case). Biopsy of the intrascrotal testis was performed in 3 patients with unilateral cryptorchidism. Histological examination was normal in two cases and abnormal in one case. The long-term outcome was characterized by:

1. Testicular atrophy in 6 patients (2.7% of cases).
2. Progression to malignancy in 3 patients (1.3% of cases).
3. Improvement of sperm parameters in 16 of 33 infertile patients (48.5%); 4 patients fathered children after treatment.

Conclusion

Orchidopexy at adulthood can lead to improvement of infertility. It can also decrease the incidence of malignancy and facilitate clinical examination looking for possible malignancy. However, the best treatment remains preventive, based on early diagnosis and orchidopexy.     

Improvement of Photorhabdus temperata strain K122 bioinsecticide production by batch and fed-batch fermentations optimization

Optimization of a fermentation process for bioinsecticides production by Photorhabdus temperata strain K122 was investigated into fully controlled 3-L fermenter using an optimized medium (OM). Development of large-scale inocula showed that the composition of the growth medium greatly influenced the physiological state of P. temperata cells. The effect of pH, agitation and dissolved oxygen concentration (DO) on the growth, culturability and oral toxicity of P. temperata cells were also investigated. Indeed, maintaining the pH at 7 and controlling DO concentration at 50 % saturation throughout the fermentation process, improved biomass production, CFU counts and oral toxicity by 41.1, 35 and 32.1 %, respectively, as compared to cultures carried out in 500 mL shake flasks. At such conditions, 8 g/L glucose fed-batch fermentation, enhanced cell lysis and variants small colony (Vsm) polymorphism appearance. To overcome such limitations, glucose concentration should be maintained at 4 g/L. In this case, P. temperata cells were produced at high cell density and culturability reaching 4.5 and 1.2 × 10⁹ cells/mL, respectively. In addition, the stability of the primary form was maintained for a long period in the stationary growth phase and Vsm polymorphism was completely avoided that can be crucial for scale-up the bioprocess of P. temperata bioinsecticide.

     

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

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 × 10⁸ 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.