Production and Characterization of Novel Board-spectrum Antimicrobial 5-butyl-2-pyridine carboxylic acid from Aspergillus fumigatus nHF-01

Objectives: The present study aims to report on the production optimization, purification, and characterization of structural and functional attributes of a novel broad-spectrum antibacterial compound produced by Aspergillus fumigatus nHF-01 (GenBank Ac. No. MN190286).Materials and Methods: The culture conditions were optimized by using rigorous culture-set preparation considering various abiotic and biotic factors for a higher amount of antimicrobial production. The produced antimicrobial was solvent extracted and purified by preparative TLC and HPLC methods followed by characterization using UV-Vis, FT-IR, ESI-MS, and 1H-NMR spectroscopy. The MIC and MBC of the antimicrobials were determined against a set of Gram-positive and Gram-negative human pathogenic bacteria. The mode of action on cellular morphology and integrity were determined by LDH and SEM studies. Its biofilm-inhibition properties and synergistic activity with antibiotics were studied. The possible cytotoxic effect on human cell lines was also tested by MTT assay. The putative target site of action was evaluated through in silico molecular docking study. Results: The micro-fungus A. fumigatus nHF-01 produced the maximum antibacterial compound while grown in a combination of 2% MEB (w/v) and 4% YE (w/v) at pH 6.0 and 20 °C temperature with 100 rpm agitation for ten days. The DCM extractable crude compound has a potent growth inhibition against the target human food and topical pathogenic bacteria at a 15 mg/ml concentration and is stable up to 100 °C. The spectroscopic studies confirmed the antimicrobial compound as 5-butyl-2-pyridine carboxylic acid with MIC values from 0.069±0.0034 to 1.12±0.052 mg/ml and from 8.925±0.39 to 17.85±0.78 mg/ml; and MBC values from 8.925±0.40 to 17.85±0.776 mg/ml and from 0.069±0.0034 to 0.139±0.0065 mg/ml against human pathogenic Gram-positive and Gram-negative bacteria, respectively. A concentration of 0.139 and 17.85 mg/ml decreased the viability sharply within 15 min of the incubation period with the gradual increase in LDH activity, indicating a robust bactericidal and lytic mode of action. The time-kill kinetics study shows that at a 17.85 mg/ml dose (i.e. MBC), the compound caused zero viability of E. coli and S. epidermidis cells from the initial log CFU/ml 5.78 after 15 h of treatment. It caused a remarkable change in morphology like the formation of blebbing, notch, rupture of the entire cell walls, and entire dissolution of cell integrity at a concentration of 4 µg/ml and 129 µg/ml. It had cytotoxicity against the tested human lung carcinoma A549 cell line. It showed a notable antibiofilm activity at 20 µg/ml and 4 µg/ml comparable to the standard antibiofilm drug usnic acid 10 µg/ml and 64 µg/ml against E. coli and B. cereus. It had a synergistic activity with streptomycin, whereas ciprofloxacin and vancomycin showed additive effects. It showed the highest binding affinities with Quinol-Fumarate Reductase (1l0v), a respiratory enzyme. Conclusion: Thus, the above findings can be concluded that the strain A. fumigatus nHF-01 produces a novel broad-spectrum antimicrobial compound 5-butyl-2-pyridine carboxylic acid with potent bactericidal activity against human food and topical pathogenic bacteria. This is the first report of such a compound from the A. fumigatus.

Broad spectrum antimicrobial PDMS-based biomaterial for catheter fabrication

Background In addition to the widespread use of antibiotics in healthcare settings, the current COVID-19 pandemic has escalated the emergence of antibiotic resistance. Nosocomial infections among hospitalized patients is a leading site for such resistant microbial colonization due to prolonged use of invasive devices and antibiotics in therapies. Invasive medical devices, especially catheters, are prone to infections that could accelerate the development of resistant microbes. Often, catheters - particularly urinary catheters - are prone to high infection rates. Antibiotic-coated catheters can reduce infection rates and although commercially available, are limited in efficacy and choices. Methods Herein, a novel and facile method to fabricate PMDS-based biomaterial for the development of antimicrobial eluting catheters is presented. Silicone based organic polymer polydimethylsiloxane (PDMS) was used to prepare a biomaterial containing novel polymeric imidazolium antimicrobial compound. Results It was found that the PDMS-based biomaterials could eradicate microbial colonization even after 60 days in culture with continuous microbial challenge, be recycled over multiple uses, stored at room temperature for long-term usage and importantly is biocompatible. Conclusion The PDMS-based biomaterial displayed biocidal functionality on microbes of clinical origin, which form major threats in hospital acquired infections. Graphical Abstract

Inhibition of Listeria monocytogenes by bacteriocin-producing Bacillus velezensis isolated from silage

The aim of this study was to investigate the production of anti-Listeria bacteriocins by naturally occurring bacteria on silage and to characterize the most promising bacteriocin. The production of bacteriocins was evaluated by the spot-on-lawn method. The presence of interfering factors and the sensitivity to proteinase K were analyzed. The spectrum of activity was determined and the most promising bacteriocin-producing isolate was identified, being selected for the subsequent experiments. The antimicrobial peptide was extracted, analyzed regarding temperature and pH sensitivities, and purified. Of the 37 isolates evaluated, seven showed anti-Listeria activity. The presence of bacteriophages and production of acidic compounds were not detected. The selected antimicrobial compound was sensitive to proteinase K and the producing-bacterium was identified as Bacillus velezensis. The crude extract maintained the antimicrobial activity in different temperatures and pH conditions. In conclusion, the bacteriocin produced by Bacillus velezensis showed strong activity against Listeria monocytogenes, and great stability to elevated temperature and adverse pH, desirable features for future biotechnological applications.

Characteristic Features and Comparative analysis of essential oil composition of selected species of Ocimum sanctum L. through GCMS

Background: The main aim of this research is to provide a literature of the Ocimum plant, to know the significance of the Ocimum species carried out by pharmacognostical study and experimental design for GC-MS.Ocimum are very important for their therapeutic potentials. among the most important aromatic herbs for its enormous medicinal properties. Methods: An extreme Attention has been put on those literature reports wherein the utilization of Tulsi and their pharmacognostical study has been done by performing morphological and microscopic leaf and experimental design by using essential oil by GC-MS instrumentation method Results: The utilization of these characteristics would be important for the drug discovery scientist to develop a specific formulation of the crude drug, which will be a magical therapeutic agent in the future, with the many advantageous. GC-MS chromatogram of the Ocimum sanctum, Ocimum canum and Ocimum gratissimum oil showed major peaks and has been identified after comparison of the mass spectra with NIST library, indicating the presence of three phytocomponents. From the results GC-MS study suggested that anethole which is well reported antimicrobial compound is more in O. canum (2.66%) in comparison to O. sanctum (1,28%) but absent in O. Gratissimum. The results indicated that the antimicrobial activity is more in O. canum due to presence high amount of anethole in comparison to O.Gratissimum, and O. Sanctum. The GC-MS study suggested that anethole which is well reported antimicrobial compound is more in O. canum (2.66%) in comparison to O. sanctum (1,28%) but absent in O. Gratissimum. Conculsion: The result showed that microscopic character of O. canum, with the characteristic GC MS analysis of the extracts, to identify different species of the ocimum plant. Ocimum sanctum L. and further experiments are required for better exploitation of essential oil for its commercial purposes.

Analysis of Antimicrobial Compound in Ziziphus Mauritiana Extract using Attenuated Total Reflection-Fourier Transform Infrared (ATR-FTIR)

Ziziphus mauritiana is locally known as Bidara that belongs to Rhamnaceae family which is a herbal plant that believed originated from Indo-Malaysian region of South-East Asia. It is commonly known for its various benefits as pharmacological such as antioxidants and antimicrobial. In order to prove its efficacy, antimicrobial compound analysis of Ziziphus mauritiana leaf extract was performed using Attenuated total reflection-fourier transform infrared (ATR-FTIR). The spectrum and wavelength obtained can be used to identify the functional group and thus, the antimicrobial compound was discovered present in the plant. A liquid-liquid extraction had been carried out to obtain the extract of Ziziphus mauritiana leaf sample and rotary evaporator is used to remove the solvent of ethyl acetate. Based on this study, Ziziphus mauritiana leaves do have antimicrobial compounds such as eugenol and vanillin which are one of the antimicrobial agents.

Spectroscopy Analysis of Antimicrobial Compound in Centella Asiatica Extract

The usage of herbal medicinal is still the widespread among society today in their daily lives. This is mostly due to the tradition of our ancestors who really relied on traditional medicine to cure diseases and improve their intelligence. Next, herbal plants are said to have more and better nutrients and nourishment than modern medicine. This is because the compound have been mixed with the use of other chemicals to produce medicines. Centella asiatica (pegaga) is an herbal plant that is commonly heard about its benefits both internally and externally. However, scientific research is needed to prove its benefits. Thus, the society do not clarified much on the actual nutrients thoroughly. Besides that, Centella asiatica is generally known to come from the Apiaceae family and this plant is an important plant with a wide range of traditional, medicinal and therapeutic values. This plant has it own speciality or strong point in which it is choosen to be mentioned in the Quran. To prove its efficacy, a spectroscopy analysis of Centella asiatica extract was performed using ATR-FTIR. The use of Centella asiatica samples has also been diversified into leaf part and stem part. This is to compare the nutrient content in the leaves. The results from this research is that Centella asiatica leaves do have antimicrobial compound. Therefore, the usage of Centella asiatica leaves in society needs to be expanded so that its nutrients can be utilized to the maximum for the benefit of the people and improvement to the national economy.