Enzymatic properties and transglycosylation of α-galactosidase from Penicillium oxalicum SO

Penicillium oxalicum SO α-galactosidase demonstrated weak hydrolysing activity but a high rate of transglycosylation in the reaction with melibiose, where the major product was 6-α-galactosyl melibiose. The transfer ratio was 83.6% and was maintained over a long reaction time of 80 h. The molecular weight was estimated to be 124,000 by SDS–PAGE. The optimal pH was ∼3 and a stable pH, with a range of 2.4–9.5, was found. The optimal temperature was ∼60 °C and the activity was stable below 60 °C. With respect to acceptor specificity, mono-alcohols, sugar alcohols and sugars were poor acceptors, but the di-alcohol ethylene glycol and the tri-alcohol glycerin were good acceptors. The percentage of transglycosylation to glycerin increased up to 41.7%, as that to melibiose decreased, with the initial glycerin concentration of 40%. The production of α-d-galactosylglycerol was 293 mg for each gram of melibiose used by the enzymatic reaction.     

The effects of the combination of Pichia membranefaciens and BTH on controlling of blue mould decay caused by Penicillium expansum in peach fruit

The feasibility of 0.2 g l⁻¹ benzo-thiadiazole-7-carbothioic acid S-methyl ester (BTH) to improve the efficacy of Pichia membranefaciens in controlling postharvest blue mould decay in peach fruit was investigated. Our results showed that biocontrol activity of P. membranefaciens against blue mould caused by Penicillium expansum in peach fruit could be enhanced by addition of 0.2 g l⁻¹ BTH. The combination of P. membranefaciens and BTH resulted in a more effective control of blue mould than individual treatment of P. membranefaciens or BTH alone. The combined treatment had a synergistic effect on the induction of superoxide dismutase, catalase, ascorbate peroxidase, chitinase and β-1,3-glucanase activities, which induced stronger disease resistance in fruit than BTH or yeast alone, and resulted in a lower lesion diameter and disease incidence of blue mould decay in peaches. Furthermore, the combined treatment did not impair the quality parameters including fruit firmness and contents of total soluble solids, titratable acidity and vitamin C of peach fruit after 6 days of storage at 20 °C. These results suggested that the use of BTH may be an effective method to improve the biological activity of P. membranefaciens.     

产壳聚糖酶的海洋青霉菌筛选及其寡营养发酵的探究

从海边海螺、贝壳及其附着物的微生物中筛选出产壳聚糖酶的青霉菌。以此菌为出发菌,以降低发酵产酶成本为目的,采用不同的发酵温度,分别添加不同诱导物进行发酵产酶,探讨温度、诱导物对菌种生长、酶活力的影响。实验结果表明:低聚糖诱导产酶效果最好,室温25℃进行壳聚糖酶发酵,普通培养基酶活力最高达3.57U/mL。海水寡营养发酵产酶的适宜培养基配方为(g/L):蛋白胨9g、葡萄糖10g的海水培养基,酶活力可以达到3.16U/mL,初步实现利用海水进行寡营养发酵产酶,该菌株具有工业应用潜力。     

Effect of ripening with Penicillium roqueforti on texture,microstructure, water distribution and volatiles of chicken breast meat

In this study, the influence of ripening with Penicillium roqueforti on texture, microstructure, protein structure, water mobility and volatile flavour compounds of chicken breast meat was investigated. Scanning electron microscopy (SEM) and transmission electron microscope (TEM) images showed that the granule formed and chicken myofibril fractured after ripening. Reduction in α-helix and increases in β-sheet structure content accompanied by decrease in hardness and springiness and increase in gumminess were found in ripened chicken breast meat. Low field nuclear magnetic resonance (LF-NMR) revealed that increasing intra-myofibrillar water and decreasing extra-myofibrillar water resulted in the higher water-holding capacity after ripening with P. roqueforti. In addition, chicken breast meat ripened with P. roqueforti contained more volatile flavour compounds, in particular aldehydes.     

Biological system for improving the availability of Tilemsi phosphate rock for wheat (Triticum aestivum L.) cultivated in Mali

The Tilemsi phosphate rock (TPR) of Mali is a good and cheaper alternative to imported phosphate fertilizers. Many soil microorganisms can also mobilize sparingly soluble inorganic phosphates, and several have a good potential to improve plant growth. With the aim of improving the response of wheat cultivated in Mali to fertilization with TPR, in this work we describe the isolation and selection from four different Malian soils of TPR-solubilizing microorganisms (TSM) with high P-mobilization activities. When the rhizosphere of three wheat cultivars (Alkama Beri, Hindi Tossom and Tetra) was used to isolate TSM, only bacterial isolates were selected. TPR-solubilizing fungi were only obtained by soil enrichment in liquid medium containing TPR as sole P source. In the rhizosphere a significant correlation was observed between the total microbial population and the number of microorganisms solubilizing TPR. No such correlation was observed in the rhizoplane. Initially 44 bacteria and 18 fungi were selected, but after 10 subcultures on agar plates and a liquid medium, only 6 bacteria and 2 fungi retained their high P solubilizing trait. A field inoculation trial was established during the growing season 2000–2001 in Koygour. Wheat cv. Tetra was inoculated with the 8 selected TSM (6 bacteria and 2 fungi) and fertilized with 30 kg ha⁻¹ P added as TPR or diammonium phosphate. The growth parameters measured were plant height at 30 and 60 days, the number of leaves per main stem at 60 days, and root and shoot dry matter yields 60 days after planting. Root colonization by indigenous arbuscular mycorrhizas (AM) was also measured in 45 day-old plants. Significant interactions were observed between TSM inoculation and P-fertilization for root colonization with AM, plant height at 30 days and root dry matter yield. The bacterial isolate Pseudomonas sp. BR2, which appeared to be a mycorrhiza helper bacterium, significantly enhanced wheat seedling emergence very early (5 days after planting) under field condition, and caused 128% increase in root dry matter yield. The two TPR-solubilizing fungal isolates Aspergillus awamori Nakazawa C1 and Penicillium chrysogenum Thom C13 also caused respectively 60 and 44% increases in root dry matter yields. The choice of the TSM BR2, C1 and C13 for further field trials is discussed. This article was previously published in Nutrient Cycling in Agroecosystems Volume 72/2 pages 147–157. The online version of the original article can be found at .     

Characterization of PEI-modified biomass and biosorption of Cu(II), Pb(II) and Ni(II)

The objective of this work is to develop a surface-modified biosorbent with enhanced sorption capacity for heavy metal ions. The biomass of Penicillium chrysogenum was modified with polyethylenimine (PEI) and then crosslinked with glutaraldehyde. The crosslinked PEI was chemically bonded on the biomass surface through the amine and carboxylate groups on the pristine biomass. The presence of the amine group was confirmed by X-ray photon spectroscopy (XPS) and Fourier transform infrared (FTIR) analysis, and the concentration of the amine groups on the biomass surface was found to be 2 mmol/g through potentiometric titration. The rugged morphology of the biomass surface after the modification was observed by scanning electron microscope (SEM). Compared with the pristine biomass, the modified biomass with amine groups showed a significant increase in sorption capacity for three metal ions, namely, copper, lead and nickel. The sorption isotherms of the biomass for three metals were well described by Langmuir equation, with a maximum sorption at 92 mg copper, 204 mg lead and 55 mg nickel per g biomass. The binding sites for the three metals attributed to the amine groups on the biomass surface were verified by FTIR analysis.     

Mycoremediation of chlorpyrifos and lambda-cyhalothrin by two species of filamentous fungi

Chlorpyrifos and lambda-cyhalothrin are two of the most commonly used insecticides in agriculture. Their residues reach water courses, affecting aquatic fauna and subsequently human beings. Aspergillus viridinutans and Penicillium implicatum isolated from water drains at El-Giza and El-Ismailia governorates were grown in potato dextrose broth media supplemented with different concentrations of chlorpyrifos and lambda-cyhalothrin. Samples, taken at 0, 7 and 14 days, were analysed for pesticide residues by gas chromatography. The fungal species showed biodegradation potentials of 2.5, 5 and 20 ppm of chlorpyrifos and lambda-cyhalothrin. Degradation percentage reached 100% after 14 days of incubation of both pesticides (2.5 ppm) individually with the two tested fungal species. The values of degradation rate, besides the weights of dry fungal biomasses ensured that the optimum chlorpyrifosconcentration for A. viridinutans and P. implicatum was 5 ppm, while the optimum lambda-cyhalothrin concentration for A. viridinutanswas 5 ppm and 2.5 ppm for P. implicatum.     

Separation of a compound effective against Biomphalaria alexandrina snails from the filtrate of Penicillium janthinellum

Biomphalaria alexandrina snails, as intermediate hosts of schistosomiasis, play a central role in dissemination of the disease. Control of these snails by chemical molluscicides adversely affects the aquatic environment, causing toxic and carcinogenic effects on non-target organisms. Searching for promising substances from biological origin becomes an urgent need to overcome these drawbacks. Screening tests were carried out on 236 fungal genera isolated from the habitat of freshwater snails in four Egyptian governorates. Twenty species were effective against B. alexandrina snails, but the most potent was Penicillium janthinellum as the value of LC₅₀ was 1.03%. Chemical analyses of this filtrate resulted in the separation of a compound effective against snails; it was identified as methyl gallate. Protein electrophoresis showed that both fungal filtrate and methyl gallate affect the protein pattern of snails’ haemolymph. Little or no mortality of Daphnia pulex individuals was observed after their exposure to sub lethal concentrations of each treatment.     

Mould growth on traditional greek sausages and penicillin production by Penicillium isolates

Visible moulds were isolated and identified from traditional Greek sausages from Northern Greece. Penicillium species were isolated from 90.8% of visibly mouldy sausages. Penicillium solitum, P. nalgiovense and P. commune species made up 60.6% of the total number of isolates. The most frequently occurring species was P. solitum (26.1%). P. nalgiovense and P. olsonii were found to be positive to penicillin production in an agar assay and further examination for antibiotic production in liquid culture with complex media designed for penicillin production, confirmed their ability for penicillin biosynthesis. Penicillin production by P. olsonii is reported for the first time in this study.