Biochemical characterization of β-galactosidases and engineering of their product specificity

De menselijke darm bevat vele triljoenen micro-organismen, met een totaal gewicht tot 2 kg. Deze darmflora is van belang voor de menselijke gezondheid; ze bevordert vertering van voedsel, produceert sommige vitaminen en helpt ziekteverwekkende bacteriën te bestrijden. Zo bevordert een gezonde darmflora de menselijke gezondheid. Prebiotica zijn speciale koolhydraten die de gezonde micro-organismen helpen te groeien die vervolgens ongezonde micro-organismen remmen, en zodoende een gezonde darmflora bevorderen. Humane melk oligosachariden (hMOS) zijn speciale prebiotica die in moedermelk zitten en sterke gezondheidsvoordelen geven aan de baby. Borstvoeding geven is echter niet voor iedereen mogelijk. In die gevallen is er de mogelijkheid flesvoeding te gebruiken om de baby te voeden. Flesvoeding is gemaakt op basis van koemelk, waar amper prebiotica in zitten. Als alternatief voor hMOS, worden galactooligosachariden (GOS) toegevoegd aan de flesvoeding, om het effect van hMOS na te bootsen. GOS zijn mengsels van koolhydraten, geproduceerd uit melk suiker door bacteriële β-galactosidase enzymen. Verschillende β-galactosidase enzymen, produceren verschillende GOS mengsels, met variatie in samenstelling en structuren, maar ook in prebiotische fucntionaliteit. Hoewel verschillende β-galactosidase enzymen en GOS mengsels bestudeerd zijn, was er nog weinig bekend over welke enzym kenmerken bepalend zijn voor de samenstelling en structuren van de GOS. Daartoe is dit onderwerp van studie in dit proefschrift, met combinaties van enzym mutagenese en gedetailleerde analyse van de gevormde producten. Er zijn eveneens nieuwe prebiotische mengsels van structuren gevormd in deze studie, die mogelijk een betere functionaliteit in flesvoeding hebben en dus de potentie hebben toepassing te vinden in de industrie

A Review of Research on Ecological Economics Based on Bibliometrics

The development of ecological economics is a major strategy for development in the 21st century. Although scholars have been rising more and more interesting for ecological economic over the past 10 years, it is still unclear what is the change will be facing in the future. In order to provide a theoretical basis for the future development of ecological economy, our article analyzes the current research progress of ecological economy on the basis of a bibliometric analysis. The results show that (1) sustainable development of an ecological economy is a hot research topic; (2) there is little cooperation and exchange between institutions and among scholars regarding ecological economics; (3) the number of publications on ecological economics is increasing, with a relatively large number being published in China. Therefore, we must strengthen the cooperation between institutions and among scholars and improve the research content, vision, and methods in this field. This study provides a theoretical basis for the future development of ecological economy

Reaction kinetics and galactooligosaccharide product profiles of the β-galactosidases from Bacillus circulans, Kluyveromyces lactis and Aspergillus oryzae

β-Galactosidase enzymes are used in the dairy industry to convert lactose into galactooligosaccharides (GOS) that are added to infant formula to mimic the molecular sizes and prebiotic functions of human milk oligosaccharides. Here we report a detailed analysis of the clearly different GOS profiles of the commercial β-galactosidases from Bacillus circulans, Kluyveromyces lactis and Aspergillus oryzae. Also the GOS yields of these enzymes differed, varying from 48.3% (B. circulans) to 34.9% (K. lactis), and 19.5% (A. oryzae). Their incubation with lactose plus the monosaccharides Gal or Glc resulted in altered GOS profiles. Experiments with (13)C6 labelled Gal and Glc showed that both monosaccharides act as acceptor substrates in the transgalactosylation reactions. The data shows that the lactose isomers β-d-Galp-(1→2)-d-Glcp, β-d-Galp-(1→3)-d-Glcp and β-d-Galp-(1→6)-d-Glcp are formed from acceptor reactions with free Glc and not by rearrangement of Glc in the active site.</p

Proses Pembelajaran Saksofon untuk Pemula di Sekolah Musik Indonesia Yogyakarta

Lembaga musik non formal khususnya di bidang pembelajaran saksofon kini semakin banyak, salah satu lembaga non formal yang menawarkan program pembelajaran saksofon yaitu Sekolah Musik Indonesia Yogyakarta yang berlokasi di jalan C. Simanjuntak. Pada pembelajaran saksofon tentunya terdapat suatu proses dan beberapa kendala baik dari faktor internal maupun eksternal, yang akhirnya mengarah terhadap bagaimana proses pembelajaran saksofon di Sekolah Musik Indonesia Yogyakarta dan apa saja kendala-kendala dalam proses pembelajaran saksofon di Sekolah Musik Indonesia yogyakarta. Pada proses pembelajaran terdapat metode yang merupakan suatu cara yang digunakan untuk mencapai suatu tujuan yang telah ditetapkan. Metode pembelajaran saksofon untuk pemula yang digunakan yaitu metode menurut George M. Bundy “The Selmer Elementary” dan metode menurut Hendry Linderman “Method for Saxophone”, adapun metode pembelajaran lainnya yang digunakan pada proses pembelajaran saksofon di Sekolah Musik Indonesia Yogyakarta sangatlah bervariasi sehingga proses pembelajaran tidak membosankan. Metode pengajaran secara umum yang digunakan yaitu metode eksperimen, tugas, diskusi, demonstrasi, tanya jawab, latihan, dan ceramah. Pada proses pembelajaran saksofon terdapat beberapa kendala baik dari faktor internal maupun eksternal yaitu meliputi lingkungan, guru, metode, kurikulum, program, materi, sarana dan prasarana. Namun di Sekolah Musik Indonesia Yogyakarta proses pembelajaran saksofon berjalan cukup baik walaupun terdapat beberapa kendala. Kata Kunci: Proses pembelajaran, Saksofon, Sekolah Musik Indonesia Yogyakart

Mental health stigma and mental health knowledge in Chinese population:a cross-sectional study

BACKGROUND: Little is known about the public stigma on mental illness and mental health knowledge (MHK) in China, public stigma and low MHK can negatively affect patients' health and increase the burden of mental disorders on society. This study aimed at investigating the rates of stigma and MHK, the correlates of stigma and MHK, and the association between MHK and stigma among a Chinese population. METHODS: The data is from the Tianjin Mental Health Survey (TJMHS), which involved a large and a representative sample of adult community residents in the Chinese municipality of Tianjin (n = 11,748). In a 12% random subsample (n = 1775) the Perceived Discrimination and Devaluation scale (PDD) and a Mental Health Knowledge Questionnaire (MHKQ) were administered. First, percentages of the responses to the individual items of the PDD and MHKQ were investigated. Second, sociodemographic correlates of PDD and MHK, and the association between stigma and MHK were investigated. RESULTS: We found that a sizable proportion of participants responded that others would hold a negative attitude towards (former) mental patients, especially with regard to engaging in closer personal relationships. Most people were not familiar about the causes, treatments and prevention of mental illness. Resident area, age, education level, Per capita family income and employment status were related to devaluation score and MHKQ score. MHK was negatively associated with public stigma. CONCLUSIONS: There is room for improvement with regard to levels of public stigma and MHK in China. Providing psychoeducation to improve public MHK could also contribute to reduction of public stigma

Synthesis of galacto-oligosaccharides derived from lactulose by wild-type and mutant β-galactosidase enzymes from Bacillus circulans ATCC 31382

Oligosaccharides derived from lactulose (β-D-Galp-(1 → 4)-D-Fru) are drawing more and more attention nowadays because of their strong resistance to gut digestion, and the interest to discover novel prebiotics. Compared to galactooligosaccharides, currently known structures of lactulose oligosaccharides are very limited. In this study, the wild-type β-galactosidase BgaD-D of Bacillus circulans ATCC 31382, as well as the derived mutant R484H, were used to synthesize oligosaccharides from lactulose. In total, 9 oligosaccharide structures were identified by MALDI-TOF-MS and NMR spectroscopy analysis. Trisaccharide β-D-Galp-(1 → 4)-β-D-Galp-(1 → 4)-D-Fru was the major structure produced by the wild-type enzyme, while the R484H mutant showed a preference for synthesis of β-D-Galp-(1 → 3)-β-D-Galp-(1 → 4)-D-Fru. Our study greatly enriched the structural information about oligosaccharides derived from lactulose