Biotechnological potential of Zymotis-2 bioreactor for the cultivation of filamentous fungi.

BACKGROUND/AIM: A new prototype of Solid-State Fermentation Bioreactor, namely "Zymotis-2 ", was developed to produce fungal spores. MAIN METHODS AND MAJOR RESULTS: A fermentation process for fungal spores, and hydrolase enzymes (endo and exoglucanases, amylases) production by Trichoderma asperellum DWG3, Aspergillus niger G131 and Beauveria bassiana was scaled-up from flasks and glass Raimbault column packed with 20 g of solid substrates (dry weight) to 5 kg of solid substrate by using the new Zymotis-2 bioreactor. Fungi strains growth using a mix of vine shoots, wheat bran, and olive pomace was tested under similar experimental conditions in Zymotis-2 bioreactor, column bioreactor and flasks in a parallel fermentation system. Overall, significant spore production on Zymotis-2 bioreactor was obtained, achieving 22.01 ± 0.01×109 spores/g DM 16.30 ± 0.07 × 109 spores/g DM, and 3.30 ± 0.07 × 109 spores/g DM for B. bassiana, T. asperellum DWG3, and A. niger G131, respectively. Forced aeration increased the endoglucanases, exoglucanases and amylases activities for T. asperellum DWG3 but B. bassiana and A. niger G131 were affected negatively by the aerated process, showing the lowest enzyme activities. CONCLUSIONS AND IMPLICATIONS: In conclusion, a high yield of spores was obtained at 137 h of cultivation time, confirming the validity of the new Zymotis-2 bioreactor to produce virulent spores at low cost by T. asperellum, B. bassiana and A. niger G131.

Use of electrospray ionization mass spectrometry for profiling of crude oil effects on the phospholipid molecular species of two marine bacteria.

We investigated the membrane lipid composition of two hydrocarbon-degrading gram-negative bacterial strains (Pseudomonas nautica IP 617 and Marinobacter hydrocarbonoclasticus) initially cultured on a soluble substrate, then on petroleum hydrocarbons, and finally taken back onto the soluble substrate. For the two strains, the growth on petroleum and the return to the initial medium showed major, but comparable, qualitative and quantitative modifications of the intact phospholipid molecular species (IPMS) composition. Furthermore, since bacterial membranes are mainly made up of phospholipids, these modifications reflected hydrocarbon assimilation, restoration abilities and membrane fluidity adaptation. The electrospray ionization mass spectrometry (ESI-MS) analysis of intact phospholipid provided some new information (e.g. sn fatty acyl chain distribution) that could not be assessed by the classical fatty acid analysis. Moreover, such information should be particularly helpful with regards to bacterial taxonomy and xenobiotic toxicity studies.

Effects of pure n-alkanes and crude oil on bacterial phospholipid classes and molecular species determined by electrospray ionization mass spectrometry.

Phospholipids are major components of bacterial membrane. Furthermore, the growth in vitro on xenobiotics such as n-alkanes, aromatic compounds or alkanols bring about to a bacterial membrane adaptive response. Concerning this work, we studied the membrane lipid composition of a hydrocarbon-degrading gram-positive bacterium (Corynebacterium sp.) on a soluble substrate and we detected four different phospholipid classes: phosphatidylglycerol, phosphatidylinositol, cardiolipin and acyl phosphatidylglycerol. In addition, a study of the lipid composition was performed after an in vitro culture on either pure n-alkane or crude oil. The growths on such hydrophobic substrates showed major qualitative and quantitative modifications. In the case of a growth on either heneicosane or crude oil, an increase of odd-numbered fatty acids was observed. Furthermore, the phospholipid polar head group composition was highly influenced by the crude oil addition. These modifications were, respectively, interpreted as the consequence of hydrocarbon assimilation and membrane fluidity adaptation. Finally, Corynebacterium sp. was taken back on the initial ammonium acetate substrate in order to determine its restoration abilities after a petroleum contamination.

Bacterial phospholipid molecular species analysis by ion-pair reversed-phase HPLC/ESI/MS.

This work set out to optimize the detection and separation of several phospholipid molecular species on a reversed-phase column with the use of an electrospray ionization/mass spectrometry-compatible counter-ion. An application of this technique concerned a qualitative and quantitative analysis of bacterial membrane phospholipids extracted from Corynebacterium species strain 8. The phospholipid classes of strain 8 were identified as phosphatidylglycerol, phosphatidylinositol, diphosphatidylglycerol, and a peculiar lipid compound, acyl phosphatidylglycerol. Most of the molecular species structures were elucidated, and regarding phosphatidylglycerol, the fatty acid positions were clearly determined with the calculation of the sn-2/sn-1 intensity ratio of the fatty acyl chain fragments.