Cold-active catalase from the psychrotolerant fungus Penicillium griseofulvum.

Cold-active catalase (CAT) elicits great interest because of its vast prospective at the medical, commercial, and biotechnological levels. The study paper reports the production of cold-active CAT by the strain Penicillium griseofulvum P29 isolated from Antarctic soil. Improved enzyme production was achieved by optimization of medium and culture conditions. Maximum CAT was demonstrated under low glucose content (2%), 10% inoculum size, temperature 20°C, and dissolved oxygen concentration (DO) 40%. An effective laboratory technology based on changing the oxidative stress level through an increase of DO in the bioreactor was developed. The used strategy resulted in a 1.7- and 1.4-fold enhanced total enzyme activity and maximum enzyme productivity. The enzyme was purified and characterized. P. griseofulvum P29 CAT was most active at approximately 20°C and pH 6.0. Its thermostability was in the range between 5°C and 40°C.

Distribution of a novel enzyme of sialidase family among native filamentous fungi.

Sialidases (neuraminidases, EC 3.2.1.18) are widely distributed in biological systems but there are only scarce data on its production by filamentous fungi. The aim of this study was to obtain information about sialidase distribution in filamentous fungi from non-clinical isolates, to determine availability of sialidase gene, and to select a perspective producer. A total of 113 fungal strains belonging to Ascomycota and Zygomycota compassing 21 genera and 51 species were screened. Among them, 77 strains (11 orders, 14 families and 16 genera) were able to synthesize sialidase. Present data showed a habitat-dependent variation of sialidase activity between species and within species, depending on location. Sialidase gene was identified in sialidase-positive and sialidase-negative strains. . Among three perspective strains, the best producer was chosen based on their sialidase production depending on type of cultivation, medium composition, and growth temperature. The selected P. griseofulvum Р29 was cultivated in 3L bioreactor at 20 °C on medium supplemented with 0.5% milk whey. The results demonstrated better growth and 2.3-fold higher maximum enzyme activity compared to the shaken flask cultures. Moreover, the early occurring maximum (48 h) is an important prerequisite for future up scaling of the process.

Protective effects of losartan on some type 2 diabetes mellitus-induced complications in Wistar and spontaneously hypertensive rats.

Diabetes mellitus type 2 (T2DM) is characterized by resistance of insulin receptors and/or inadequate insulin secretion resulting in metabolic and structural complications including vascular diseases, arterial hypertension and different behavioral alterations. We aimed to study the effects of the antihypertensive angiotensin AT1 receptor antagonist losartan on the T2DM-induced changes of exploratory behavior, anxiety, nociception and short term memory in normotensive Wistar and spontaneously hypertensive rats (SHRs). The experimental model of T2DM induced by a combination of high fat diet and streptozotocin, decreased exploratory activity and increased the level of carbonylated proteins in selected brain structures in both strains; as well it increased corticosterone level, pain threshold, anxiety-like behavior, and decline short term memory only in SHRs. Losartan treatment alleviated some of the T2DM- induced metabolic complications, abolished the T2DM-induced hypo activity, and normalized the corticosterone level, carbonylated proteins in brain, nociception and memory. Losartan did not exert effect on the anxiety behavior in both strains. We showed that T2DM exerted more pronounced negative effects on the rats with comorbid hypertension as compared to normotensive rats. Overall effects on the studied behavioral parameters are related to decreased exploration of the new environment, increased anxiety-like behavior, and decline in short-term memory. The systemic sub-chronic treatment with an angiotensin AT1 receptor antagonist losartan ameliorated most of these complications.

Moderate protective effect of Kyotorphin against the late consequences of intracerebroventricular streptozotocin model of Alzheimer's disease.

The established decrease in the level of endogenous kyotorphin (KTP) into the cerebrospinal fluid of patients with an advanced stage of Alzheimer's disease (AD) and the found neuroprotective activity of KTP suggested its participation in the pathophysiology of the disease. We aimed to study the effects of subchronic intracerebroventricular (ICV) treatment (14 days) with KTP on the behavioral, biochemical and histological changes in rats with streptozotocin (STZ-ICV)-induced model of sporadic AD (sAD). Three months after the administration of STZ-ICV, rats developed increased locomotor activity, decreased level of anxiety, impaired spatial and working memory. Histological data from the STZ-ICV group demonstrated decreased number of neurons in the CA1 and CA3 subfields of the hippocampus. The STZ-ICV group was characterized with a decrease of total protein content in the hippocampus and the prefrontal cortex as well as increased levels of the carbonylated proteins in the hippocampus. KTP treatment of STZ-ICV rats normalized anxiety level and regained object recognition memory. KTP abolished the protein loss in prefrontal cortex and decrease the neuronal loss in the CA3 subfield of the hippocampus. STZ-ICV rats, treated with KTP, did not show significant changes in the levels of the carbonylated proteins in specific brain structures or in motor activity and spatial memory compared to the saline-treated STZ-ICV group. Our data show a moderate and selective protective effect of a subchronic ICV administration of the dipeptide KTP on the pathological changes induced by an experimental model of sAD in rats.

Potential of ligninolytic enzymatic complex produced by white-rot fungi from genus Trametes isolated from Bulgarian forest soil.

Because of the crucial role of ligninolytic enzymes in a variety of industrial processes, the demand for a new effective producer has been constantly increasing. Furthermore, information on enzyme synthesis by autochthonous fungal strains is very seldom found. Two fungal strains producing ligninolytic enzymes were isolated from Bulgarian forest soil. They were identified as being Trametes trogii and T. hirsuta. These two strains were assessed for their enzyme activities, laccase (Lac), lignin peroxidase (LiP) and Mn-dependent peroxidase (MnP) in culture filtrate depending on the temperature and the type of nutrient medium. T. trogii was selected as the better producer of ligninolytic enzymes. The production process was further improved by optimizing a number of parameters such as incubation time, type of cultivation, volume ratio of medium/air, inoculum size and the addition of inducers. The maximum activities of enzymes synthesized by T. trogii was detected as 11100 U/L for Lac, 2.5 U/L for LiP and 4.5 U/L for MnP after 14 days of incubation at 25°C under static conditions, volume ratio of medium/air 1:6, and 3 plugs as inoculum. Among the supplements tested, 5% glycerol increased Lac activity to a significant extent. The addition of 1% veratryl alcohol had a positive effect on MnP.

Antimicrobial and antioxidant potential of different solvent extracts of the medicinal plant Geum urbanum L.

Many Geum species are known to be rich in biologically active compounds and therefore could be a source of new natural products with pharmacological potential. The medicinal plant Geum urbanum L. is widespread in Bulgaria and has been used in folk medicine. In the present study, the methanol extracts of the roots and aerial parts of G. urbanum and their fractions (petroleum ether, ethyl acetate and n-butanol) were investigated for antibacterial and radical scavenging activity. The ethyl acetate and n-butanol fractions inhibited the growth of Gram-positive pathogenic and opportunistic bacteria from the genus Staphylococcus (MIC EtOAc: 0.078 mg/ml aerial and 0.156 mg/ml roots; MIC n-BuOH: 0.156 mg/ml aerial and 1.25 mg/ml roots) and the species Bacillus cereus stronger than the other extracts and fractions tested (MIC EtOAc: 0.078 mg/ml aerial and 0.156 mg/ml roots; MIC n-BuOH: 0.156 mg/ml aerial and 0.078 mg/ml roots), and showed corresponding radical scavenging activity (EtOAc: EC50 1.5 µg/ml aerial, 0.8 µg/ml roots; n-BuOH: 4.5 µg/ml aerial; 3.7 µg/ml roots). Additionally, their total phenolic content was quantified (% of dry EtOAc fractions of roots 61%, of arial parts 32%; of dry n-BuOH fractions of roots 16%, of arial parts 13%). Seven compounds were isolated and identified spectroscopically from the ethyl acetate extract. Two acetylated ellagic acid rhamnosides were found for the first time in the genus Geum and three others, tormentic acid, niga-ichigoside F1, and 3,3'-di-O-methylellagic acid-4-O-ß-D-glucopyranoside, were newly detected for the species G. urbanum. Our results reveal that G. urbanum L. is a perspective medicinal plant and deserves further, more detailed studies.

Production, purification, and characterization of a novel cold-active superoxide dismutase from the Antarctic strain Aspergillus glaucus 363.

The Antarctic fungal strain Aspergillus glaucus 363 produces cold-active (CA) Cu/Zn-superoxide dismutase (SOD). The strain contains at least one gene encoding Cu/Zn-SOD that exhibited high homology with the corresponding gene of other Aspergillus species. To our knowledge, this is the first nucleotide sequence of a CA Cu/Zn-SOD gene in fungi. An effective laboratory technology for A. glaucus SOD production in 3 L bioreactors was developed on the basis of transient cold-shock treatment. The temperature downshift to 10 °C caused 1.4-fold increase of specific SOD activity compared to unstressed culture. Maximum enzyme productivity was 64 × 10(3) U kg(-1) h(-1). Two SOD isoenzymes (Cu/Zn-SODI and Cu/Zn-SODII) were purified to electrophoretic homogeneity. The specific activity of the major isoenzyme, Cu/Zn-SODII, after Q-Sepharose chromatography was 4000 U mg(-1). The molecular mass of SODI (38 159 Da) and of SODII (15 835 Da) was determined by electrospray quadropole time-of-flight (ESI-Q-TOF) mass spectrometry and dynamic light scattering (DLS). The presence of Cu and Zn were confirmed by inductively coupled plasma mass spectrometry (ICP-MS). The N-terminal amino acid sequence of Cu/Zn-SODII revealed a high degree of structural homology with Cu/Zn-SOD from other fungi, including Aspergillus species.