Mycelial Growth-promoting Potential of Extracellular Metabolites of Paraburkholderia spp. Isolated from Rhizopogon roseolus Sporocarp

This study aimed to investigate the effect of potential metabolite(s) produced by Paraburkholderia spp. isolated from the Rhizopogon roseolus (shouro mushroom) sporocarp on the mycelial growth of R. roseolus. For this purpose, we selected two molecularly identified bacteria: P. fungorum GIB024 and P. caledonica KN1. Direct confrontation assay at three different distances, a pour plate method that sampled bacterial spent broth either with and without agitation at 25 °C, and an indirect confrontation assay was carried out in order to assess the R. roseolus growth-promoting ability of Paraburkholderia spp. These assessments were carried out in a 1:5 diluted Melin-Norkran-modified medium with glucose (hs-dMMN) and without glucose (ls-dMMN). GIB024 promoted the growth of R. roseolus in ls-dMMN in short distance, whereas KN1 inhibited the growth of the fungus in that condition. In hs-dMMN, both bacteria have neutral or slightly promotion effect toward R. roseolus. We determined from the spent broth analysis that Paraburkholderia spp. that grew axenically under static conditions had a more pronounced mycelial growth-promoting effect on R. roseolus than under agitation conditions. We also found that high concentration of spent broth resulted in a decrease in mycelial growth-promoting ability. Volatile metabolite(s) produced by both bacteria did not promote the mycelial growth of R. roseolus. In conclusion, Paraburkholderia spp. exhibited a species- and nutrient (sugar)-dependent ability to promote the mycelial growth of R. roseolus, and the bacterial soluble metabolite(s) play a crucial role in their growth-promoting ability

Optical character recognition

Optical Character Recognition (OCR) is the process of extracting the characters from a digital image. The concept behind OCR is to acquire a document in image or pdf formats and extract the characters from that image and present it to the user in an editable format. The author of this thesis tested an Artificial Neural Network (ANN), which is a mathematical representation of the functionality of the human brain, using Back-propagation Algorithm with test case files of English alphabets. The purpose of this thesis was to test systems capable of recognizing English alphabets with different fonts, and to be familiar with ANN and digital image processing and apply it for character recognition. Scientific journals and reports were used to research the relevant information required for the thesis project. The chosen software was then trained and tested with both computer and hand-written alphabets in image files. The tests revealed that the OCR software is able to recognize both computer and hand-written alphabets, and learns to do it better with each iteration. The study shows that although the system needs more training for hand-written characters than computerized fonts, the use of ANN in OCR is of great benefit and allows for quicker and better character recognition

Insight into the substrate specificity change caused by the Y227H mutation of α-glucosidase III from the European honeybee (<i>Apis mellifera</i>) through molecular dynamics simulations

<div><p>Honey from the European honeybee, <i>Apis mellifera</i>, is produced by α-glucosidases (HBGases) and is widely used in food, pharmaceutical, and cosmetic industries. Categorized by their substrate specificities, HBGases have three isoforms: HBGase I, II and III. Previous experimental investigations showed that wild-type HBGase III from <i>Apis mellifera</i> (WT) preferred sucrose to maltose as a substrate, while the Y227H mutant (MT) preferred maltose to sucrose. This mutant can potentially be used for malt hydrolysis because it can efficiently hydrolyze maltose. In this work, to elucidate important factors contributing to substrate specificity of this enzyme and gain insight into how the Y227H mutation causes substrate specificity change, WT and MT homology models were constructed, and sucrose/maltose was docked into active sites of the WT and MT. AMBER14 was employed to perform three independent molecular dynamics runs for these four complexes. Based on the relative binding free energies calculated by the MM-GBSA method, sucrose is better than maltose for WT binding, while maltose is better than sucrose for MT binding. These rankings support the experimentally observed substrate specificity that WT preferred sucrose to maltose as a substrate, while MT preferred maltose to sucrose, suggesting the importance of binding affinity for substrate specificity. We also found that the Y227H mutation caused changes in the proximities between the atoms necessary for sucrose/maltose hydrolysis that may affect enzyme efficiency in the hydrolysis of sucrose/maltose. Moreover, the per-residue binding free energy decomposition results show that Y227/H227 may be a key residue for preference binding of sucrose/maltose in the WT/MT active site. Our study provides important and novel insight into the binding of sucrose/maltose in the active site of <i>Apis mellifera</i> HBGase III and into how the Y227H mutation leads to the substrate specificity change at the molecular level. This knowledge could be beneficial in the design of this enzyme for increased production of desired products.</p></div

Binding free energies and their components for sucrose/WT, maltose/WT, sucrose/MT, and maltose/MT complexes.

<p>Binding free energies and their components for sucrose/WT, maltose/WT, sucrose/MT, and maltose/MT complexes.</p