Current Issue : April - June Volume : 2019 Issue Number : 2 Articles : 6 Articles
Background: A promoter that drives high-level, long-term expression of the target gene under substrate limited\ngrowth conditions in the absence of an artificial inducer would facilitate the efficient production of heterologous\nproteins at low cost. A novel phosphate-regulated expression system was constructed using the promoter of the\nphytase encoding gene phyL from Bacillus licheniformis for the overexpression of proteins in this industrially relevant\nhost.\nResults: It is shown that the phyL promoter enables a strong overexpression of the heterologous genes amyE and\nxynA in B. licheniformis when cells were subjected to phosphate limitation. Whether B. licheniformis can use phytate\nas an alternative phosphate source and how this substrate influences the PphyL controlled gene expression under\ngrowth conditions with limited inorganic phosphate concentrations were also investigated. It is shown that B.\nlicheniformis cells are able to use sodium phytate as alternative phosphate source. The addition of small amounts of\nsodium phytate (....) to the growth medium resulted in a strong induction and overexpression of both model\ngenes in B. licheniformis cells under phosphate limited growth conditions.\nConclusions: The PphyL controlled expression of the investigated heterologous genes in B. licheniformis is strongly\nauto-induced under phosphate limited conditions. The proposed PphyL expression system enables an\noverexpression of target genes in B. licheniformis under growth conditions, which can be easily performed in a\nfed-batch fermentation process....
Background: CRISPR/Cas9 has wide application potentials in a variety of biological species including Trichoderma\nreesei, a filamentous fungus workhorse for cellulase production. However, expression of Cas9 heterologously in the\nhost cell could be time-consuming and sometimes even troublesome.\nResults: We tested two gene disruption methods in T. reesei using CRISPR/Cas9 in this study. The intracellularly\nexpressed Cas9 led to unexpected off-target gene disruption in T. reesei QM9414, favoring inserting 9- or 12-bp at\n70- and 100-bp downstream of the targeted ura5. An alternative method was, therefore, established by assembling\nCas9 and gRNA in vitro, followed by transformation of the ribonucleoprotein complex with a plasmid containing\nthe pyr4 marker gene into T. reesei TU-6. When the gRNA targeting cbh1 was used, eight among the twenty seven\ntransformants were found to lose the ability to express CBH1, indicative of successful cbh1 disruption through\ngenome editing. Large DNA fragments including the co-transformed plasmid, chromosomal genes, or a mixture of\nthese nucleotides, were inserted in the disrupted cbh1 locus.\nConclusions: Direct transformation of Cas9/gRNA complex into the cell is a fast means to disrupt a gene in T. reesei\nand may find wide applications in strain improvement and functional genomics study....
This study was carried out to investigate the antimicrobial activities of bacterial\nisolates of maize against plant pathogens as well as their growth responses\nto some environmental parameters. Twenty four bacterial isolates were obtained\nfrom maize plants collected from the Department of Biological Sciences,\nAfeBabalola University, Ado-Ekiti. The isolates were characterized by\ntheir biochemical and physiological characteristics and were identified as\nKurthiazopfu, Morganellamorganic , Rhodococcusequi , Bacillus subtilis ,\nCatabaterhongkongensis , Brevibacteriumotitidis , Lactobacillus coleohominis ,\nStaphylococcus aureus , Propionibacterium acnes among others. Their responses\nto different NaCl concentrations, sugars, temperature as well as antibiotics\nwere determined. Most of the isolates were able to withstand various\nenvironmental parameters in which they were subjected to. Also, eight isolates\nwere able to ferment sucrose. The bacterial isolates showed a degree of\nresistance to the antibiotics tested. There was a high prevalence of multidrug\nresistant bacteria showing resistance to 3 - 8 drugs. The antagonistic effect of\nthe bacterial isolates against selected fungi was determined. None of the isolates\nshowed antagonistic potential against the fungal pathogens. However,\nthe supposed antagonistic bacterial species can be genetically modified to\nproduce secondary metabolites that will result in biocontrol....
Background and objectives: Irrational and repeated use of broad spectrum\nantibiotics for infectious diarrhea in children has resulted in their increased\nresistance along with several systemic toxic effects. Probiotics are also used in\nthe management of infectious diarrhea as these are supposed to be favorable\nin promoting overall health benefits including stability of the intestinal flora.\nHowever, these agents are not used as an alternative to antibiotics as their exact\nbactericidal/bacteriostatic effects have not been evaluated on the basis of\nany clinical or in-vitro samples (Culture and Sensitivity test). Hence the aim\nof our study was to compare the culture and sensitivity patterns of standard\nantibiotics and two probiotics, Lactobacilli (Lactobacillus paracasei/Lactobacillus\nacidophilus ) and Saccharomyces boulardii used for the treatment of infectious\ndiarrhea in children less than 5 years of age in a tertiary care hospital of\nKarachi, Pakistan. Methodology: This prospective quasi experimental study\nwas conducted for a period of six months. After getting informed consent\nfrom parents/guardians, the stool samples were obtained from children of\nages, 6 months to 5 years, presented with signs and symptoms of diarrhea in\noutpatient department (OPD) or being referred to microbiology department\nfor stool C/S (culture and sensitivity). The sensitivity patterns of the cultured\nisolates were assessed for standard antibiotics according to the CLSI guidelines\n(2018), while the two probiotics (Lactobacilli and Saccharomyces boulardii\n) were evaluated by means of Dried Modification method. The data was analyzed using statistical software SPSS version 19.0. Results: A total number\nof 325 stool samples were collected, out of which 152 samples were positive\nfor pathogens i.e. E. coli , Klebsiella and Salmonella typhi. The sensitivity of\ncombination of Lactobacilli for E. coli , Klebsiella and Salmonella typhi was\n28.3%, 25% and 25% respectively. While, for Saccharomyces boulardii the\nsensitivity for E. coli , Klebsiella and Salmonella typhi was 37%, 32.1% and\n25% respectively, which were slightly higher or equivalent to commonly prescribed\nantibiotics such as Amoxicillin/Clavulanic acid, Ceftazidime, Ampicillin,\nCefotaxime, Cefuroxime, Ceftriaxone, Aztreonam, Trimethoprim/\nSulfmethoxazole and Nalidixic acid. In comparison, the antibiotics which are\nnot frequently used for infectious diarrhea showed higher sensitivities for all\nisolated organisms; as for E. coli the highest sensitivity was observed for\nAmikacin (96.7%), Gentamycin (95.7%) Imipenim (95.7%) and Piperacillin/\nTazobactam (84.8%). Moreover, for Klebsiella the highest sensitivity was\nobserved for Imipenim (98.2%), followed by Amikacin (94.6%), Piperacillin/\nTazobactam (92.9%) and Gentamycin (89.3%). Conclusion: On in-vitro\ncultured samples, the two probiotics Lactobacilli and Saccharomyces boulardii\nhave shown slightly higher or equivalent sensitivity in comparison to the\nmost commonly prescribed antibiotics (Amoxicillin/Clavulanic acid, Ceftazidime,\nAmpicillin, Cefotaxime, Cefuroxime Ceftriaxone, Aztreonam, Trimethoprim/\nSulfmethoxazole and Nalidixic acid). However, both probiotics displayed\nlower sensitivity in comparison to some broad spectrum but less\ncommonly prescribed antibiotics (Amikacin, Gentamycin, Imipenim and Piperacillin/\nTazobactam) in our clinical settings....
Human gut flora-mediated non-digestible fraction of wild edible and common\nedible was observed for pH at every 6 hours regime. The antioxidant\nability was measured up to 18 hours of fermentation with different associated\ngut microbes. Changes in pH provide an overview of the fermentation process.\nIn the in-vitro study of antioxidant activity by DPPH test, anti-oxidants values\nshowed differences, depending on the substrate and microbial fermenters\nused for fermentation. At first 6 hours interval, it was observed that the wild\nbean-Feregede fermented by Enterococcus feacalis exerts the highest antioxidant\ncapacity of 0.0043 Cathechin equivalents. It also exerts lowest antioxidant\ncapacity of 0.0034 Cathechin equivalents after 18 hours fermentation.\nThese data provided preliminary evidence that consumption of beans diet\nsuch as the wild bean-Otili , Feregede , pakala and edible bean-oloyin is limiting\nfactor to liberation of antioxidant components during the gastrointestinal\ndigestion. Thus, disruption of normal cellular homeostasis by redox signaling\nmay result in the development of various gastrointestinal pathological\nconditions, including inflammatory bowel diseases....
Subgingival bacteria are continually exposed to gingival crevicular fluids that are derived from serum, which contain various\nbactericidal agents. The periodontopathic bacterium Porphyromonas gingivalis has been demonstrated to possess a variety of\nabilities to resist bactericidal agents, due towhich it is able to propagate in the subgingival environment.We previously demonstrated\nthat the major surface glycoproteins of P. gingivalisâ??Pgm6 and Pgm7, also called outer membrane protein A-like proteins\n(OmpALPs)â??mediate resistance to the bactericidal activity of human serum, but their precise role remains unknown. In this study,\nwe investigated the sensitivity of the wild-type and Pgm6/Pgm7-deficient P. gingivalis strains toward major antimicrobial peptides\nin the oral cavity, human................
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