Optimization of media for β-fructofuranosidase production by Aspergillus niger in submerged and solid state fermentation

The kinetics of β-fructofuranosidase (Ffase) production by Aspergillus niger in submerged (SmF) and solid-state fermentation (SSF) systems was investigated. The maximum productivity of Ffase (81.8 U/l per h) was obtained in SSF for 72 h while it was 18.3 U/l per h in SmF for 120 h. The productivity of extra cellular Ffase produced in SSF was 5-fold higher than in SmF. Optimization of fermentation medium for Ffase production was carried out using De Meo's fractional factorial design with seven components such as (NH₄)₂SO₄, KH₂PO₄, FeSO₄, MgSO₄ · 7H₂O, sucrose, urea and yeast extract. The media designed for SmF after two steps of optimization supported the growth of A. niger and higher productivity of Ffase (58.3 U/l per h) than with the medium before optimization. The optimized medium of SmF when used in SSF, did not improve the Ffase productivity and therefore medium for SSF was optimized independent of SmF. After two optimization steps, the media was defined for SSF which supported the growth and high level of Ffase productivity (149.1 U/l per h) in SSF compared to the medium before optimization (81.8 U/l per h) and optimized medium for SmF (58.3 U/l per h). Our results suggested that the optimized media for SmF and SSF for the production of Ffase have to be different.     

Structure based design of compounds from natural sources for diabetes and inflammation

Medicinal plants and marine sources are important elements of indigenous medical systems worldwide. The natural drugs from medicinal plants and marine sources have received considerable interest in treatment of diabetes and inflammation. Based on literature, alpha glucosidase, aldose reductase and PTP1B enzymes were chosen as anti-diabetes targets and PLA₂ was chosen for the anti-inflammatory target. In our study, plant and bromophenols (BPs) inhibitors were screened using High Throughput Virtual screening (HTVS) followed by Induced Fit Docking (IFD) studies were carried out against diabetes and inflammation targets. The IFD result of natural inhibitors has showed favorable docking score, glide energy and hydrogen bonds interactions with the active site residues. Some of the natural inhibitors successively satisfied all the in silico parameters among the others and seem to be potent inhibitors against diabetes and inflammation.     

Transfer and expression of broad host range plasmids in Zymomonas mobilis

Summary The broad host range vectors, pKT210, pKT212, pKT248, pKT240, pGSS33 were mobilized into Zymomonas mobilis with the help of conjugative plasmids belonging to various incompatibility groups. The vectors pKT210, pKT212, pKT248, pGSS33 were stably maintained in Zymomonas mobilis in contrast to the conjugative plasmids. Based on these results we suggest the potential usefulness of these vectors as cloning vehicles in Zymomonas mobilis.     

Ammonia-excreting mutant strain of the cyanobacterium Anabaena variabilis supports growth of wheat

Summary Growth of wheat in a nitrogen-free hydroponic co-culture with a mutant strain of the cyanobacterium Anabaena variabilitis (strain SA-1) was enhanced over plants grown with the parent strain SA-0. This increase was achieved in the dry weight, grain yield, and total nitrogen content of the plants. Nitrogenase activity of the mutant strain SA-1 was increased in a co-culture of the cyanobacterial mutant with wheat plants compared to the activity of the wild-type strain in association with wheat. Offprint requests to: M. Gunasekaran     

Response surface methodology for the optimization of <Emphasis Type="Italic">α</Emphasis>-amylase production by <Emphasis Type="Italic">Streptomyces</Emphasis> sp. ML12 using agricultural byproducts

Amylases constitute one of the most important groups of enzymes for commercial use. In the present study, production of α-amylase was optimized using a newly isolated actinobacterial strain from the coral reef environment of the Gulf of Mannar Biosphere Reserve, India. It was identified as Streptomyces sp. ML12 based on chemotaxonomy, cultural and morphological characteristics, carbon source utilization and 16S rRNA gene sequencing. Fermentation variables were selected in accordance with the Plackett-Burman design and were optimized by response surface methodology. Five significant variables (rice bran and wheat bran — both agricultural byproducts, sodium chloride, magnesium sulphate and incubation period) were selected for the optimization via central composite design. The optimal features were rice bran (5.5 g/100 mL), wheat bran (5.3 g/100 mL), sodium chloride (2.8 g/100 mL), magnesium sulphate (1.4 g/100 mL) and 8 days of incubation period. Optimization of the medium with the above tested features increased the amylase yield by 4.4-fold.     

Effect of temperature and concentration on rheological behavior of xanthan-carob mixed gels

The gelation and melting behavior of 1∶1, 1∶3 xanthan-carob mixed gels were evaluated at isothermal and non-isothermal states, as a function of total polymer concentrations of 0.1, 0.5 and 1%. A thermal hysteresis was observed between gelation and melting. The higher the polymer concentration, the higher the melting temperature. The gelation points were determined by three criteria. Depending on the criterion used the gelation temperature was different (52 to 70°C). Pseudoequilibrium modulus and elastic active network chain (EANC) concentration were calculated from the plateau modulus in the frequency spectrum. Temperature dependence of the monomeric friction coefficient was estimated from the relaxation time and EANC. Time-temperature superposition theory was not applicable due to dramatic phase transitions occurring during the gelation of X/C mixture.