Biology subjects

Samuel, A. Z.

Publications and source records attributed to Samuel, A. Z..

4 recordsLinked to original sources

bioRxiv2022

Mycelial differentiation linked avermectin production in studied with Raman imaging

Streptomyces avermitilis is a gram-positive bacterium that undergoes complex physiological and morphological differentiation during its life cycle, which has implications in secondary metabolites production. Avermectin, produced by S. avermitilis, is widely used as an anthelmintic and insecticidal agent. In this study, we have applied Raman microspectroscopic imaging to elucidate the correlation between production of avermectin and the morphological differentiation in S. avermitilis. We demonstrate distinctive variations in the localization of avermectin at various morphological stages, such as, substrate mycelium, spore-bearing mycelium, spiral spore chains under solid culture conditions. Under liquid culture condition, however, avermectin is detected only in mycelia after early MII stage of differentiation. Morphological differentiation was observed in liquid and solid cultures, but the chemical profiles of the mycelia were substantially different. Spherical bodies containing avermectin with characteristically different chemical composition to that of spores were also observed under solid culture, which suggests possible release of extracellular vesicles (EVs). Key pointsO_LIAvermectin production is regulated during mycelial differentiation C_LIO_LILiquid and solid culture conditions affects mycelial differentiation C_LIO_LIRaman microspectroscopic analysis reveals localization profiles of avermectin C_LI

microbiology↗

bioRxiv2021

Raman microspectroscopy imaging analysis of extracellular vesicles (EVs) biogenesis by filamentous fungus Penicilium chrysogenum

Mechanism of production of extracellular vesicles (EVs) and their molecular contents are of great interest owing to their diverse roles in biological systems and are far from being completely understood. Even though, cellular cargo release mediated by EVs have been demonstrated in several cases, their role in secondary metabolite production and release remains elusive. In this study we investigate this aspect in detail using Raman micro-spectroscopic imaging. We provide considerable evidence to suggest that the release of antibiotic penicillin by filamentous fungus Penicillium chrysogenum involves EVs. Morphological modifications of the fungal body during biogenesis, changes in cell composition at the locus of biogenesis, and major molecular contents of the released EVs are also revealed in this study. ImportanceExtracellular vesicles (EVs) play a key role in cellular communications. EVs role in functioning of fungi are relatively less explored. Here we show selective enrichment of chemical contents at certain locations of mycelium of P. chrysogenum forming protruding regions. Secondary metabolite penicillin is excessively localized in them. We provide evidence to show that EVs are released from these protrusions. Raman imaging has been applied for molecular profiling of the mycelium and for characterizing chemical contents of the EVs. Our study suggests a possible general role of EVs in the release of antibiotics from the producing organisms.

cell biology↗

bioRxiv2020

Detection of Penicillin G Produced by Penicillium chrysogenum KF 425 in Vivo with Raman Microspectroscopy and Multivariate Curve Resolution-Alternating Least Squares Methods

Raman microspectroscopy is a minimally invasive technique that can identify molecular structure without labeling. In this study, we demonstrate in vivo detection of the bioactive compound penicillin G inside Penicillium chrysogenum KF425 fungus cells. Highly overlapped spectroscopic signatures acquired using Raman microspectroscopic imaging are analyzed using a multivariate curve resolution-alternating least squares (MCR-ALS) method to extract the pure spectra of individual molecular constituents. In addition to detecting multiple constituents such as proteins and lipids, we observe the subcellular localization of penicillin G like granule particle inside the fungus body. To date, there have been no reports of direct visualization of intracellular localization of penicillin G. The methodology we present in this article is expected to be applied as a screening tool for the production of bioactive compounds by microorganisms.

microbiology↗

bioRxiv2020

Molecular profiling of lipid droplets inside HuH7 Cells with Raman micro-spectroscopy

Raman imaging has become an attractive technology in molecular biology because of its ability to detect multiple molecular components simultaneously without labeling. Two major limitations in accurately accounting for spectral features, viz. background removal and spectral unmixing, have been overcome by employing a modified and effective routine in multivariate curve resolution (MCR). With our improved strategy, we have spectrally isolated seven structurally specific biomolecules without any post-acquisition spectral treatments. Consequently, the isolated intensity profiles reflected concentrations of corresponding biomolecules with high statistical accuracy. Our study reveals the changes in the molecular composition of lipid droplets (LD) inside HuH7 cells and its relation to the physiological state of the cell. Further, we show that the accurate separation of spectral components permits analysis of in vivo structural modification of molecules after cellular uptake. A detailed discussion is presented to highlight the potential of Raman spectroscopy with MCR in semi-quantitative molecular profiling of living cells.

bioengineering↗