295 research outputs found
Pectinolytic activity of Aspergillus section Nigri strains
Pectinases are a heterogeneous group of related enzymes that hydrolyze pectic substances
present mostly in plants. Pectinases are produced by plants, fungi, yeasts
and bacteria. Filamentous fungi are good producers of pectinolytic enzymes (e.g.,
exopolygalacturonase (exo-PG) and endopolygalacturonase (endo-PG) and Aspergillus
niger is the most commonly used fungal species for industrial production of pectinolytic
enzymes. The application of pectinolytic enzymes plays an important role
in food technology. In juice production, these enzymes have been used to improve
the yield, decrease the viscosity, clarify the juices and make them more stable. In
this context, the concept of using filamentous fungi and row and cheaper materials
for pectinase production is an important parameter in technological development.
In the present study a microplate method was developed for a rapid screening of
Aspergillus strains. Fifty-tree strains of Aspergillus section Nigri obtained from
the University of Recife Mycology (URM) culture collection and 8 of the Micoteca
da Universidade do Minho (MUM) culture collection were used. Orange peel was
the unique carbon source in the composition of the culture medium. The samples
were incubated at 25 ºC for 120 h. After 24, 48, 72, 96 and 120 h the exo-PG and
endo-PG were assessed using absorbance colorimetric and decrease in viscosity
methods, respectively. The utilization of orange peel allowed the detection of exo-PG
and endo-PG activity for all strains studied. The maximum exo-PG and endo-PG
activity was obtained by strain URM5162 to the values 4.37 U and 2.13 U, respectively.
This method and substrate may be useful to reduce the time for selecting
promising strains and in reducing the enzyme production costs. The strain is now
being used in a bioreactor and the enzymes and their mechanisms are also under
further investigation
Molecular cloning and functional characterization of a catalase gene from a Bacillus safensis strain isolated from an oil-impacted Brazilian mangrove sediment.
Implicit Regularization and Renormalization of QCD
We apply the Implicit Regularization Technique (IR) in a non-abelian gauge
theory. We show that IR preserves gauge symmetry as encoded in relations
between the renormalizations constants required by the Slavnov-Taylor
identities at the one loop level of QCD. Moreover, we show that the technique
handles divergencies in massive and massless QFT on equal footing.Comment: (11 pages, 2 figures
Screening of bacterial isolates from Brazilian oil-impacted mangrove for lipase and esterase activities.
Partitioning and purification of polygalacturonases produced by Aspergillus niger URM 5162 using PEG-phosphate in an aqueous two-phase system
Pectinases, or pectinolytic enzymes, are naturally produced by plants, filamentous fungi, bacteria and yeasts. The pectinases are
of great importance to clarify and reduce viscosity in fruit juices, improving and increasing tbe filtration efficiency. When used
in the crushing of grapes or wine must improve juice extraction, reduce the time to clarify and enhance tbe content ofterpenes in
wine. The filamentous fungi most frequently used fur industrial purposes because as much as 90% ofthe enzyme can be excreted
into the culture medium. The partitioning and purification of polygalacturonases (PG) produced by Aspergillus niger URM
5162 were investigated in aqueous two-phase systems (ATPS), furmed by polyetbylene glycol and phosphate salts
(PE(ijlhosphate). To evaluate the effect oftbe 4 independent variables- molar mass ofpolyetbylene glycol (PEG) (400-8000
g1nol MPEG), PEG concentration (12.5-17.5%, w/w- CPEG), phosphate concentration (15-25%, ...W, CPHOS) and pH (6.0, 8.0)
- on the 3 response variables: partition coefficient (K), activity yield (Y) and purification fàctor (PF), a fuctorial design (24) was
used. The endo-polygalacturonases (endo-PG) were prefurentially partitioned in tbe top phase. For endo-PG, the highest values
for the response variables K, Y and PF of 1.23, 74.04% and 8.18, respectively, were obtained for a CPEG of 12.5% (...W), MPEG
of8000 g1nol, and CPHOS of25% (w/w) at pH 6.0. Also, exo-polygalacturonases (exo-PG) were preferentially partitioned in the
top phase. ln tbis case, the highest values ofK (2.40), Y (33.33%), and PF (1.98) were obtained with a MPEG of 8000 g1nol,
CPEG of 12.5% (...W), and CPHOS of25% (...W) at pH 6.0. ln both cases, MPEG had a positive influence on K, Y and PF. The
conditions ofMPEG 8000 g1nol, CPEG of 12.5% (...W), and CPHOS of25% (...W) at pH 6.0 were considered the most suitable
for tbe purification of PG produced by A. niger URM 5162. Furtbermore, MPEG and CPHOS were the most important
independent variables. The PEG/phosphate system is a useful cost-effective altemative for PG purification
Teores foliares de N, P e K em eucaliptos sob diferentes adubações em Porto Velho, Rondônia.
O objetivo deste trabalho foi avaliar os teores foliares de N, P e K em clones de eucalipto sob diferentes adubações em Porto Velho, RO
Primate Archaeology Evolves
Since its inception, archaeology has traditionally focused exclusively on humans and our direct ancestors. However, recent years have seen archaeological techniques applied to material evidence left behind by non-human animals. Here, we review advances made by the most prominent field investigating past non-human tool use: primate archaeology. This field combines survey of wild primate activity areas with ethological observations, excavations and analyses that allow the reconstruction of past primate behaviour. Because the order Primates includes humans, new insights into the behavioural evolution of apes and monkeys also can be used to better interrogate the record of early tool use in our own, hominin, lineage. This work has recently doubled the set of primate lineages with an excavated archaeological record, adding Old World macaques and New World capuchin monkeys to chimpanzees and humans, and it has shown that tool selection and transport, and discrete site formation, are universal among wild stone-tool-using primates. It has also revealed that wild capuchins regularly break stone tools in a way that can make them difficult to distinguish from simple early hominin tools. Ultimately, this research opens up opportunities for the development of a broader animal archaeology, marking the end of archaeology’s anthropocentric era
Regularization Independent Analysis of the Origin of Two Loop Contributions to N=1 Super Yang-Mills Beta Function
We present a both ultraviolet and infrared regularization independent
analysis in a symmetry preserving framework for the N=1 Super Yang-Mills beta
function to two loop order. We show explicitly that off-shell infrared
divergences as well as the overall two loop ultraviolet divergence cancel out
whilst the beta function receives contributions of infrared modes.Comment: 7 pages, 2 figures, typos correcte
Uniparental Genetic Heritage of Belarusians: Encounter of Rare Middle Eastern Matrilineages with a Central European Mitochondrial DNA Pool
Ethnic Belarusians make up more than 80% of the nine and half million people inhabiting the Republic of Belarus. Belarusians together with Ukrainians and Russians represent the East Slavic linguistic group, largest both in numbers and territory, inhabiting East Europe alongside Baltic-, Finno-Permic- and Turkic-speaking people. Till date, only a limited number of low resolution genetic studies have been performed on this population. Therefore, with the phylogeographic analysis of 565 Y-chromosomes and 267 mitochondrial DNAs from six well covered geographic sub-regions of Belarus we strove to complement the existing genetic profile of eastern Europeans. Our results reveal that around 80% of the paternal Belarusian gene pool is composed of R1a, I2a and N1c Y-chromosome haplogroups – a profile which is very similar to the two other eastern European populations – Ukrainians and Russians. The maternal Belarusian gene pool encompasses a full range of West Eurasian haplogroups and agrees well with the genetic structure of central-east European populations. Our data attest that latitudinal gradients characterize the variation of the uniparentally transmitted gene pools of modern Belarusians. In particular, the Y-chromosome reflects movements of people in central-east Europe, starting probably as early as the beginning of the Holocene. Furthermore, the matrilineal legacy of Belarusians retains two rare mitochondrial DNA haplogroups, N1a3 and N3, whose phylogeographies were explored in detail after de novo sequencing of 20 and 13 complete mitogenomes, respectively, from all over Eurasia. Our phylogeographic analyses reveal that two mitochondrial DNA lineages, N3 and N1a3, both of Middle Eastern origin, might mark distinct events of matrilineal gene flow to Europe: during the mid-Holocene period and around the Pleistocene-Holocene transition, respectively
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