An Organic Solvent-Tolerant Lipase with Both Hydrolytic and Synthetic Activities from the Oleaginous Fungus Mortierella echinosphaera

Lipase enzymes of the oleaginous fungal group Mortierella are rarely studied. However, considering that most commercial lipases are derived from filamentous fungal sources, their investigation can contribute to the cost-effective development of new biotechnological processes. Here, an extracellular lipase with a molecular mass of 30 kDa was isolated from Mortierella echinosphaera CBS 575.75 and characterized. The purified lipase exhibited an optimal p-nitrophenyl palmitate (pNPP)-hydrolyzing activity at 25 °C and pH 6.6–7.0 and proved to be highly stable at temperatures up to 40 °C and under broad pH conditions. The enzyme was active under low temperatures, retaining 32.5% of its activity at 10 °C, and was significantly stable in polar and non-polar organic solvents. The Km, Vmax, and kcat for pNPP were 0.336 mM, 30.4 μM/min, and 45.7 1/min for pNPP and 0.333 mM, 36.9 μM/min, and 55.6 1/min for pNP-decanoate, respectively. The pNPP hydrolysis was inhibited by Hg2+, N-bromosuccinimide, and sodium dodecyl sulfate, while ethylenediaminetetraacetic acid and metal ions, such as Ca2+, Mg2+, Na+, and K+ enhanced the activity. The purified lipase had non-regioselective activity and wide substrate specificity, showing a clear preference for medium-chained p-nitrophenyl esters. Besides its good transesterification activity, the enzyme appeared as a suitable biocatalyst to operate selective esterification reactions to long-chained alkyl esters. Adsorption to Accurel MP1000 improved the storage stability of the enzyme at 5 °C. The immobilized lipase displayed tolerance to a non-aqueous environment and was reusable for up to five cycles without significant loss in its synthetic and hydrolytic activities. These findings confirm the applicability of both the free and the immobilized enzyme preparations in future research

Characterization of novel surfactin isoforms and the effects of different cultivation parameters on their production by bacillus subtilis

Surfactin is a lipopeptide-type biosurfactant produced mainly by the gram-positive microorganism Bacillus subtilis. It consists of a peptide loop of seven amino acids and a hydrophobic fatty acid chain (C12 – C16). Surfactins are proved to exhibit various biological activities, such as anti-tumor, anti-viral and anti-inflammatory effects. According to these properties, different therapeutic and environmental applications of surfactins are considered. The chemical composition of surfactins could be varied in the length of the fatty acid chain and in the sequence of the amino acids of the peptide chain generating a wide spectrum of different homologues and isomers. The chemical composition of these isoforms could be elucidated via mass spectrometry by the analysis of MSn fragmentation pattern. Furthermore, depending on the cultivation conditions, the production of surfactins are affected resulting in various rates of the different isoforms produced. In this work a mixture of surfactins were extracted from the strain Bacillus subtilis (SZMC 6179J) and were examined by HPLC-ESI-IT-MS technique. To increase the separation of the components with higher masses a gradient elution was applied using a nonpolar solvent system, which led to their proper elution and characterization of their structures. Both the length of the linked fatty acids and the peptide sequences were also investigated during the MS2 spectra analyses of the sodiated precursor ions. The results led to the discovery of a novel, recently unknown group of surfactin forms possessing glutamic acid in as the fifth amino acid residue instead of the aspartic acid described previously at this position. To examine the effects of the culture media on the surfactin production, it was modified with various carbon sources and metal ions. It was reaffirmed that altering the cultivation parameters could enable the improved production of certain surfactin variants, which could serve possibility for their further preparative purification and structural elucidation. The research was supported through the New National Excellence Program of the Ministry of Human Capacities

Immunotoxicological investigation of subacute combined exposure with low doses of pb, hg and cd in rats

Detectable interactions between NOEL (No Observed Effect Level) doses of Pb, Hg and Cd in general toxicological, hematological, and immune function parameters were investigated. The metals (Pb-acetate, 20 mg/kg; HgCl 2, 0.40 mg/kg; CdCl2, 1.61 mg/kg) were combined. First, the rats received the combination Pb + Hg + Cd for 4 weeks per os. Significant difference vs. control was found only in the weight of lung and popliteal lymph node (PLN). The Pb + Hg and Pb + Cd combinations significantly decreased the PLN to 100 g body weight and PLN to brain weight ratio, and Pb+Hg also decreased the relative adrenal weight. After 12 weeks treatment with the same doses, effects on the thymus, kidney, and adrenal weights in the Pb + Hg, and thymus weight in the Pb + Cd, combination were seen. Pb + Cd also affected the white and red blood cell count and hematocrit. Combined with Hg or Cd, NOEL dose Pb showed toxicity, indicating that exposure limits may be inefficient in combined exposure situations. Š 2006 AkadÊmiai Kiadó

Identifications of Surfactin-Type Biosurfactants Produced by Bacillus Species Isolated from Rhizosphere of Vegetables

Surfactins are cyclic lipopeptides consisting of a β-hydroxy fatty acid of variable chain length and a peptide ring of seven amino acids linked together by a lactone bridge, forming the cyclic structure of the peptide chain. These compounds are produced mainly by Bacillus species and are well regarded for their antibacterial, antifungal, and antiviral activities. For their surfactin production profiling, several Bacillus strains isolated from vegetable rhizospheres were identified by their fatty acid methyl ester profiles and were tested against phytopathogen bacteria and fungi. The isolates showed significant inhibition against of E. amylovora, X. campestris, B. cinerea, and F. culmorum and caused moderate effects on P. syringae, E. carotovora, A. tumefaciens, F. graminearum, F. solani, and C. gloeosporioides. Then, an HPLC-HESI-MS/MS method was applied to simultaneously carry out the quantitative and in-depth qualitative characterisations on the extracted ferment broths. More than half of the examined Bacillus strains produced surfactin, and the MS/MS spectra analyses of their sodiated precursor ions revealed a total of 29 surfactin variants and homologues, some of them with an extremely large number of peaks with different retention times, suggesting a large number of variations in the branching of their fatty acid chains

Identification of Aspergillus species in Central Europe able to produce G-type aflatoxins

The occurrence of potential aflatoxin producing fungi was examined in various agricultural products and indoor air in Central European countries including Hungary, Serbia and Croatia. For species identification, both morphological and sequence based methods were applied. Aspergillus flavus was detected in several samples including maize, cheese, nuts, spices and indoor air, and several isolates were able to produce aflatoxins. Besides, three other species of Aspergillus section Flavi, A. nomius, A. pseudonomius and A. parasiticus were also isolated from cheese, maize and indoor air, respectively. This is the first report on the occurrence of A. nomius and A. pseudonomius in Central Europe. All A. nomius, A. pseudonomius and A. parasiticus isolates were able to produce aflatoxins B1, B2, G1 and G2. The A. nomius isolate came from cheese produced very high amounts of aflatoxins (above 1 mg ml–1). All A. nomius, A. pseudonomius and A. parasiticus isolates produced much higher amounts of aflatoxin G1 then aflatoxin B1. Further studies are in progress to examine the occurrence of producers of these highly carcinogenic mycotoxins in agricultural products and indoor air in Central Europe

Halláscsökkenést okozó etiológiai tényezők cochleáris implantáción átesett gyerekeknél

Absztrakt: Bevezetés: Veleszületett halláscsökkenés 1000 újszülöttből 1–3 esetben fordul elő. A gyermekkori súlyos fokú percepciós halláscsökkenés hátterében számos ok szerepelhet. Az esetek döntő százalékában genetikai eredet valószínűsíthető, de emellett lehet infekció, fejlődési rendellenesség és egyéb szerzett megbetegedések is. Célkitűzés: Célunk volt a Semmelweis Egyetem Fül-, Orr-, Gégészeti és Fej-, Nyaksebészeti Klinikáján a 18 év alatti, cochlearis implantáción átesett betegek között az etiológiai tényezők előfordulási arányának felmérése. Módszer és eredmények: A halláscsökkenés okát betegeink 62,9%-ában meg tudtuk határozni. A leggyakoribb etiológia a gap junction protein β-2 gén c.35delG patogén mutációja, mely a vizsgált populációban 38,8%-os allélfrekvenciát mutatott. Emellett az infektív eredet (10,1%), a meningitishez, illetve a cytomegalovirusfertőzéshez társuló halláscsökkenés fordult elő nagyobb százalékban. Betegeink 79,7%-a részesült a beszédfejlődés lezáródását megelőzően műtéti rehabilitációban, a veleszületett halláscsökkent gyermekek 11,2%-a azonban továbbra is későn diagnosztizált eset volt. Következtetés: Eredményeink alapján elmondható, hogy a gyermekkori súlyos fokú halláscsökkenés esetén fontos a genetikai eredet tisztázása. Az időben megkezdett rehabilitáció a gyermek egész életére hatással van, késői implantáció esetén a gyermek beszédfejlődése jelentősen elmarad. A késői implantációk magas aránya a 2015-ben bevezetett új újszülöttkori hallásszűrés-protokollal, valamint az orvoskollégák megfelelő tájékoztatásával és a betegeknek a megfelelő centrumba történő irányításával várhatóan csökkenthető. Orv Hetil. 2019; 160(21): 822–828. | Abstract: Introduction: Congenital sensorineural hearing loss is one of the most common sensory defects affecting 1–3 children per 1000 newborns. There are a lot of causes which result in congenital hearing loss, the most common is the genetic origin, but infection, cochlear malformation or other acquired causes can be reasons as well. Aim: The aim of this study was to establish the etiological factors of congenital profound sensorineural hearing loss in children who underwent cochlear implantation. Results: Our results show that the origin of the hearing loss was discovered in 62.9% of our patients. The most common etiological factor was the c.35delG mutation of the gap junction protein β-2 gene, the allele frequency was 38.7% in our cohort. Infection constituted to 10.1%, and meningitis and cytomegalovirus infection were the second most common cause. 79.9% of our patients received sufficient hearing rehabilitation before the end of the speech development’s period (6 years old), but 11.2% of our cases were still diagnosed late. Conclusions: Based on our data we can state that genetic evaluation is crucial in the diagnostic process of congenital profound sensorineural hearing loss. Sufficient hearing rehabilitation affects the whole life of the child, and by late cochlear implantation the speech development falls behind. We can decrease the ratio of the late implantation with the new protocol of newborn hearing screening, and with sufficient information provided to the colleagues, so the children may be referred to the proper center for rehabilitation without delay. Orv Hetil. 2019; 160(21): 822–828

Preservation effect of cinnamon and clove essential oil vapors on shelled walnut

Shelled walnut (Juglans regia) kernels are prone to rancidity during storage. In this study we examined the preservation effect of cinnamon and clove essential oil (EO) vapors compared to cold storage and vacuum packaging by measuring the hexanal content, indicating rancidity, in stored walnut kernels. Odor and taste of stored shelled walnut was investigated by sensory evaluation and by measuring residues of the main EO components in the kernels. During storage under EO vapors, cinnamaldehyde and eugenol were absorbed on the surface of walnuts in a time-dependent manner changing the odor and taste of the kernels. Clove (Syzygium aromaticum) EO prevented rancidity and EO treated kernels were rated as acceptable by the sensory panel while cinnamon EO treatment increased rancidity compared to the other treatments and the control samples