Impact of Alternative Growth Supplements on Antimicrobial Susceptibility Testing of Neisseria gonorrhoeae.

Purpose: The accurate detection of antibiotic susceptibility of Neisseria gonorrhoeae (N. gonorrhoeae) is of great importance for the treatment of patients with gonorrhea as well as to hinder the progress of drug resistance. To promote the application of gonococcal antibiotic susceptibility monitoring in primary hospitals and remote medical institutions, this study evaluated the effect of alternative growth supplements on the antibiotic susceptibility testing of N. gonorrhoeae isolates. Methods: We divided the antimicrobial-containing media into three groups by adding different growth supplements (sterile defibrinated sheep blood, bovine hemoglobin, and Vitox). We tested the antimicrobial susceptibility of 80 N. gonorrhoeae isolates in different groups against eight antibiotics. Nonparametric signed-rank tests were utilized to compare the minimum inhibitory concentration (MIC) results of each group. Taking the MIC results of Vitox group as expected, the essential agreement (EA) and category agreement (CA) of the other two groups were calculated. Results: For the group using sheep blood as growth supplements, the EA values and CA values of each antibiotic were above 90.00% and minor error rates were less than 7.00%. No very major error and major error were observed. For the group using hemoglobin as growth supplements, the EA values of the susceptibility results of zoliflodacin, penicillin, and ceftriaxone were lower than 90.00%. The overall MIC results of using hemoglobin as a growth supplement were higher than those of sheep blood and Vitox in the susceptibility testing of these three antibiotics. Conclusion: Compared with the expected results, sheep blood may be considered for the use as an alternative material for N. gonorrhoeae antibiotics susceptibility surveillance, while hemoglobin may not be suitable for supplement to antimicrobial-containing medium.

Optimization of the composition of a solid culture medium for Mycobacterium avium subsp. paratuberculosis using factorial design and response surface methodology.

AIM: To develop an optimized solid culture medium for improved growth of Mycobacterium avium subsp. paratuberculosis (MAP). METHODS AND RESULTS: Seven medium constituents (factors) were assessed at various concentrations for their ability to positively affect MAP growth. The factors tested were Tween 80, egg yolk, casitone, taurocholic acid, Mycobactin J, agar and either OADC or ADC supplement. After an initial screening of individual factors, a fractional factorial design and a response surface methodology (RSM) central composite design were used to assess the effects of multiple factors simultaneously and design a new solid culture medium. MAP growth became visible on streak plates of the optimized solid medium 2 weeks earlier than on Herrold's egg yolk medium (HEYM). CONCLUSIONS: MAP grew faster on the optimized solid medium than on HEYM. It consisted of Middlebrook 7H9 broth with 1.0% Tween 80, 0.019% casitone, 1.4% bacteriological agar, 10% egg yolk, 10% ADC and 1.65 µg ml-1 Mycobactin J. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first study to use an RSM approach to optimize the composition of a solid medium for MAP culture. The new medium could improve MAP culture in future by reducing incubation times and increasing MAP colony numbers.

Characterizing the effects of different chemicals on stem bending of cut snapdragon flower.

BACKGROUND: This study investigated the effects of ethylene release compounds (ethephon), ethylene-action inhibitors (silver thiosulfate: STS), and nitric oxide donor (sodium nitroprusside: SNP) on stem bending of snapdragon flowers. Moreover, the effects of plant growth supplements [6-benzyladenine (BA), gibberellic acid 3 (GA3), and calcium chloride (CaCl2)] on the stem bending were also extensively investigated. RESULTS: Ethephon completely prevented stem bending until 9 days after treatment (9 DAT). STS exhibited the highest bending rate, while SNP did not significantly affect the bending compared to the controls. The bending results were associated with the results of stem curvature, relative shoot elongation, ethylene production, and lignin content, that are involved in the stem bending mechanism. This was proven by the expression analysis of genes involved in ethylene and lignin biosynthetic pathways. The addition of plant growth supplements slightly or significantly delayed stem bending in the treatments (control, SNP, and STS) and significantly reduced petal senescence in ethephon at 9 DAT. CONCLUSION: These results show the preventive role of ethephon in the stem bending of cut snapdragon. Moreover, the combination of ethephon with supplements also provided information that could guide the development of strategies to delay stem bending in other cut flowers that undergo serious bending during a short vase life.

Enhanced production of cordycepin in Ophiocordyceps sinensis using growth supplements under submerged conditions.

Cordycepin is a crucial bioactive compound produced by the fungus Cordyceps spp. Its therapeutic potential has been recognized for a wide range of biological properties such as anticancer, anti-diabetic, antidepressant, antioxidant, immunomodulation, etc. Moreover, its human random clinical trials depicted a promising anti-inflammatory activity that reduced the airway inflammation remarkably in asthmatic patients. But its overexploitation and low production of cordycepin in naturally growing biomass are insufficient to meet its existing market demand for its therapeutic use. Therefore, strategies for enhancement of cordycepin production in Cordyceps spp. are warranted. However, specifically, wild type Ophiocordyceps sinensis possesses a very low content of cordycepin and has restricted growth in natural mycelial biomass. To overcome these limitations, this study attempted to enhance cordycepin production in its mycelial biomass in vitro under submerged conditions by adding various growth supplements. The effect of these growth supplements was evaluated by reversed-phase high-performance liquid chromatography (RP-HPLC) which demonstrated that among nucleosides- hypoxanthine and adenosine; amino acids-glycine and glutamine; plant hormones- 1-naphthaleneacetic acid (NAA) and 3-indoleacetic acid (IAA); vitamin-thiamine (B1) from each group of growth supplements yielded a higher amount of cordycepin with 466.48 ±â€¯3.88, 380.23 ±â€¯1.78, 434.97 ±â€¯2.32, 269.78 ±â€¯2.92, 227.61 ±â€¯2.34, 226.02 ±â€¯1.69 and 185.26 ±â€¯2.35 mg/L respectively as compared to control with 13.66 ±â€¯0.64 mg/L. Further, at the transcriptional level, quantitative real time-polymerase chain reaction (qRT-PCR) analysis of genes associated with metabolism and cordycepin biosynthesis depicted significant upregulation of major downstream genes- NT5E, RNR, purA, and ADEK which corroborated well with RP-HPLC analysis. Taken together, the present study identified growth supplements as potential precursors to activate the cordycepin biosynthesis pathway leading to improved cordycepin production in O. sinensis.