• Journal of Applied Biological Chemistry
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• v.61 no.1
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• pp.69-73
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• 2018

Oak mushroom (Lentinus edodes) is cultivated by using oak logs and sawdust medium. Green mold (Trichoderma) infection on these media severely suppresses the growth of oak mushroom. Usages of antibiotics and chemicals are not generally allowed to control of green mold since the mushroom is a fresh food. Tolaasin and its analogues, peptide toxins secreted by Pseudomonas tolaasii, have the antifungal activity and they have been successful to control the green mold disease. When the green mold, Trichoderma harzianum H1, was cultured in the presence of these toxins, the growth of fungus was effectively suppressed. In sawdust media, when the bacterial culture supernatants were sprayed on the aerial hyphae of green molds, the fungal growth was completely suppressed. Particularly, the antifungal activity was greatly increased by the combined culture extracts of P. tolaasii 6264 and HK11 strains. Therefore, these bacterial strains and their peptide toxins were able to suppress the growth of green molds and these can be good candidates to prevent from Trichoderma disease in oak mushroom cultivation.

• Journal of Microbiology and Biotechnology
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• v.32 no.6
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• pp.816-823
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• 2022

The rapid spread of superbugs leads to the escalation of infectious diseases, which threatens public health. Endolysins derived from bacteriophages are spotlighted as promising alternative antibiotics against multi-drug resistant bacteria. In this study, we isolated and characterized the novel Salmonella typhimurium phage PBST08. Bioinformatics analysis of the PBST08 genome revealed putative endolysin ST01 with a lysozyme-like domain. Since the lytic activity of the purified ST01 was minor, probably owing to the outer membrane, which blocks accessibility to peptidoglycan, antimicrobial peptide cecropin A (CecA) was fused to the N-terminus of ST01 to disrupt the outer membrane. The resulting CecA::ST01 has been shown to have increased bactericidal activity against gram-negative pathogens including Pseudomonas aeruginosa, Klebsiella pneumoniae, Acinetobacter baumannii, Escherichia coli, and Enterobacter cloacae and the most affected target was A. baumannii. In the presence of 0.25 µM CecA::ST01, A. baumannii ATCC 17978 strain was completely killed and CCARM 12026 strain was wiped out by 0.5 µM CecA::ST01, which is a clinical isolate of A. baumannii and resistant to multiple drugs including carbapenem. Moreover, the larvae of Galleria mellonella could be rescued up to 58% or 49% by the administration of CecA::ST01 upon infection by A. baumannii 17978 or CCARM 12026 strain. Finally, the antibacterial activity of CecA::ST01 was verified using 31 strains of five gram-negative pathogens by evaluation of minimal inhibitory concentration. Thus, the results indicate that a fusion of antimicrobial peptide to endolysin can enhance antibacterial activity and the spectrum of endolysin where multi-drug resistant gram-negative pathogens can be efficiently controlled.

• Journal of Microbiology and Biotechnology
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• v.24 no.8
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• pp.1065-1072
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• 2014

Doxorubicin, produced by Streptomyces peucetius ATCC 27952, is tightly regulated by dnrO, dnrN, and dnrI regulators. Genome mining of S. peucetius revealed the presence of the IclR (doxR) type family of transcription regulator mediating the signal-dependent expression of operons at the nonribosomal peptide synthetase gene cluster. Overexpression of doxR in native strain strongly repressed the drug production. Furthermore, it also had a negative effect on the regulatory system of doxorubicin, wherein the transcript of dnrI was reduced to the maximum level in comparision with the other two. Interestingly, the overexpression of the same gene also had strong inhibitory effects on the production of actinorhodin (blue pigment) and undecylprodigiosin (red pigment) in Streptomyces coelicolor M145, herboxidiene production in Streptomyces chromofuscus ATCC 49982, and spinosyn production in Saccharopolyspora spinosa NRRL 18395, respectively. Moreover, DoxR exhibited pleiotropic effects on the production of blue and red pigments in S. coelicolor when grown in different agar media, wherein the production of blue pigment was inhibited in R2YE medium and the red pigment was inhibited in YEME medium. However, the production of both blue and red pigments from S. coelicolor harboring doxR was halted in ISP2 medium, whereas S. coelicolor produced both pigmented antibiotics in the same plate. These consequences demonstrate that the on and off production of these antibiotics was not due to salt stress or media compositions, but was selectively controlled in actinomycetes.

• Korean Journal of Microbiology
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• v.42 no.3
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• pp.165-171
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• 2006

ERM proteins transfer the methyl group to $A_{2058}$ in 23S rRNA to confer the resistance to MLS (macrolide-lincosamide-streptogramin B) antibiotics on microorganism ranging from antibiotic producers to pathogens. To define the functional role of peptide segment encompassing amino acid residues 1 to 25 in NTER (N-terminal end region) of ErmSF, one of the ERM proteins, DNA fragment encoding mutant protein deprived of that peptide was cloned and overexpressed in E. coli to obtain a purified soluble form protein to the apparent homogeneity in the yield of 12.65 mg per liter of culture. The in vitro activity of mutant protein was found to be 85% compared to wild type ErmSF, suggesting that this peptide interact with substrate to affect the enzyme activity. This diminished activity of mutant protein caused the delayed expression of antibiotic resistance in vivo, that at fIrst cells expressing mutant protein showed the retarded growth due to the antibiotic action but with time cells inhibited by antibiotic gradually recovered the viability to exert the resistance to the same extent as those with wild type protein.

• Microbiology and Biotechnology Letters
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• v.21 no.6
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• pp.564-569
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• 1993

AF-001A is a novel antifungal cyclic glyco-peptise isolated from Pseudomonas cepacia AF6008. AF-001A is a mixture of AF-011A1 and AF-001A2. Each compound contains glycine(1), serine(2), asparagine(1), 2,4-diaminobutyric acid(1), beta-hydroxytyrosine(1), xylose(1) and a methylene chain amino acid(1). Additionally, A1 contains one beta-hydroxyasparagine that is replaced with as asparagine in A2. AF-011A showed high in vitro antifungal activity against various animal and plant pathogenic fungi and caused no irritation on the skin of rabbits.

• KSBB Journal
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• v.27 no.1
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• pp.9-15
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• 2012

Antimicrobial peptides are widely used in various organisms as a defense system against infection. The peptides are lethal towards bacteria and fungi, however have minimal toxicity in mammalian and plant cells. In this aspect, it is considered that antimicrobial peptides are new alternative materials for defensing against microbial infection. Here, we describe overall characteristics of antimicrobial peptides based on the mechanism of action, classification of the peptides, report detection/screening methods and chemical/biological production. It is expected that understanding of innate immune system based on antimicrobial peptides tends to develop novel natural antimicrobial agents, which might be applied for defensing pathogenic microorganisms resistant to conventional antibiotics.

• Journal of Fisheries and Marine Sciences Education
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• v.28 no.6
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• pp.1640-1650
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• 2016

In this study, the effect of the polychaete antimicrobial peptide as feed additives on fish, olive flounder (Paralichythys olivaceus) and black rockfish (Sebastes schlegelii), immune activity was described. The antimicrobial peptide of the polychaete was induced by peptidoglycan from Micrococcus luteus. The fish were fed an experimental diet supplemented with 0%, 0.05%, 0.1%, 0.5% or 1% of immune induced the polychaete to a commercial diet. Haematological parameters, nonspecific immunes and stress were evaluated 2, 4, 6 and 8 weeks during fed. The resistance against bacteria, Edwardsiella tarda and Streptococcus iniae, were analysed on after 8 weeks. The haematological parameters were not significantly changed among tested groups. But the lysozyme activities were significantly high in the 0.1% and 0.5% supplement group of olive flounder and black rockfish, respectively. Additionally, cortisol in plasma was low in the 0.1% and 0.5% supplement group of olive flounder and black rockfish, respectively. And resistance of these supplement groups were significantly induced against bacterial injection.

• Journal of Veterinary Science
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• v.24 no.3
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• pp.44.1-44.17
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• 2023

Background: Antibiotic resistance is a significant public health concern around the globe. Antimicrobial peptides exhibit broad-spectrum and efficient antibacterial activity with an added advantage of low drug resistance. The higher water content and 3D network structure of the hydrogels are beneficial for maintaining antimicrobial peptide activity and help to prevent degradation. The antimicrobial peptide released from hydrogels also hasten the local wound healing by promoting epithelial tissue regeneration and granulation tissue formation. Objective: This study aimed at developing sodium alginate based hydrogel loaded with a novel antimicrobial peptide Chol-37(F34-R) and to investigate the characteristics in vitro and in vivo as an alternative antibacterial wound dressing to treat infectious wounds. Methods: Hydrogels were developed and optimized by varying the concentrations of crosslinkers and subjected to various characterization tests like cross-sectional morphology, swelling index, percent water contents, water retention ratio, drug release and antibacterial activity in vitro, and Pseudomonas aeruginosa infected wound mice model in vivo. Results: The results indicated that the hydrogel C proved superior in terms of cross-sectional morphology having uniformly sized interconnected pores, a good swelling index, with the capacity to retain a higher quantity of water. Furthermore, the optimized hydrogel has been found to exert a significant antimicrobial activity against bacteria and was also found to prevent bacterial infiltration into the wound site due to forming an impermeable barrier between the wound bed and external environment. The optimized hydrogel was found to significantly hasten skin regeneration in animal models when compared to other treatments in addition to strong inhibitory effect on the release of pro-inflammatory cytokines (interleukin-1β and tumor necrosis factor-α). Conclusions: Our results suggest that sodium alginate -based hydrogels loaded with Chol-37(F34-R) hold the potential to be used as an alternative to conventional antibiotics in treating infectious skin wounds.

• Journal of Life Science
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• v.22 no.3
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• pp.340-346
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• 2012

Bacterial resistance to antibiotics and residues of antibiotics in poultry products have encouraged the use of probiotics, prebiotic substrates, and synbiotic combinations of prebiotics and probiotics as alternative approaches to the use of antibiotics in poultry. The present study was carried out to evaluate the effect of a new probiotic CS61 culture on growth performance, feed conversion efficiency, and safety in broiler chickens, and to evaluate its value as an alternative for antibiotics used as a feed additive. Two dosages of CS61 culture (0.1% and 1%) were fed to chickens for 28 days. The results showed that terminal body weight and daily weight gain in the treatment groups increased in a dose-dependent manner when compared with the control group. Dietary supplementation with CS61 culture also improved feed conversion rate compared to the control group. There were no treatment-related toxic effects in terms of clinical findings, mortality, necropsy findings, hematology, or serum biochemistry parameters in any group tested. The nitric oxide assay showed that CS61 peptide has a dose-dependent inhibitory effect on lipopolysaccharide-induced nitric oxide production in RAW 264.7 cells. The results of this experiment indicated that dietary supplementation of CS61 culture may improve growth performance and feed conversion efficiency in chickens through its anti-inflammatory effect.

• BMB Reports
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• v.46 no.5
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• pp.282-287
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• 2013

Cecropin A and papiliocin are novel 37-residue cecropin-like antimicrobial peptides isolated from insect. We have confirmed that papiliocin possess high bacterial cell selectivity and has an ${\alpha}$-helical structure from $Lys^3$ to $Lys^{21}$ and from $Ala^{25}$ to $Val^{35}$, linked by a hinge region. In this study, we demonstrated that both peptides showed high antimicrobial activities against multi-drug resistant Gram negative bacteria as well as fungi. Interactions between these cecropin-like peptides and phospholipid membrane were studied using CD, dye leakage experiments, and NMR experiments, showing that both peptides have strong permeabilizing activities against bacterial cell membranes and fungal membranes as well as $Trp^2$ and $Phe^5$ at the N-terminal helix play an important role in attracting cecropin-like peptides to the negatively charged bacterial cell membrane. Cecropin-like peptides can be potent peptide antibiotics against multi-drug resistant Gram negative bacteria and fungi.