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Deoxyribonucleic acid (DNA)
or oligonucleotides, can be modified in several ways as chemical
degradation by electrophilic reaction, attack of radicals, hydrolytic deamination or oxidative damage
caused by ionizing radiation. This work discussed these degradation mechanisms,
determining the effects on these biomolecules. The actual knowledge about DNA
damages only permits partial enzymatic repair treatments.
Three water-borne bacterial isolates were collected
from the Houston metropolitan area. Each isolate was capable of growing upon carbon
limited media inoculated with the organophosphorus (OP) compound paraoxon. All
isolates were able to efficiently metabolize paraoxon and, to a lesser
degree, methyl parathion to p-nitrophenol.
16S rDNA genome sequencing with universal bacterial primers identified the isolates
as species belonging to the genera Aeromonas, Steno- trophomonas, or Exiguobacterium. All screened isolates harbor organophosphorus
degradation (opd) genes that are
approximately 99% similar over approximately 660 base pairs sequenced
to one first isolated from Sphingobium fuliginis ATCC 27551 (formerly Flavobacterium sp. ATCC 27551). Additionally, two isolates KKWT11, identified as a putative Senotro-
phomonas maltophilia, and KKBO11, identified as a putative Exiguobacterium
indicum, were found to possess genomic DNA that closely matched a metallo- beta-lactamase
that has been reported to function as a methyl parathion degradation (mpd)
gene suggesting that both of these strains are prime candidates for
wastewater remediation of a broad range of OP compounds.
The degradation behaviors of Thai Bombyx mori called Samrong and Nanglai silk fibroins exposure to protease enzymes; protease XIV, protease XXIII and α-chymotrypsin type II were studied in this work. The degradation behaviors were expressed by their weight loss, morphological and secondary structure changes as well as thermal properties. Samrong showed higher percentage of weight loss than Nanglai. SEM micrographs indicated that silk fibroin were de- stroyed and showed many holes on their fiber surfaces. All of silk samples were increasable destroyed when exposure to the protease enzyme for long incubation period. With thermal analysis, both silk fibroin presented the thermal stability in the same profile. The result suggested that the selected silk fibroin should be composed of similar pattern of amino acids and their ratios. However, the protease susceptibility of each silk fibroin slightly varied in case of morphology observation. This might be affected by their genetic variety.