Types Of Microbial Cells Research Articles

A comparative analysis of capping and reducing agents of microbial cell Aspergillus niger and Bacillus subtilis for biosynthesis of Ag doped ZnO nanoparticles

In this study, green synthesis of Ag doped ZnO (AZNPR) has been carried out using the sol-gel method at pH 8.0, using two types of microbial cells, namely Aspergillus niger and Bacillus subtilis as capping and reducing agents. This work centred on the phytomediated biosynthesis and characterisation of AZNPR and its biological utility. Based on infrared analysis, phytochemicals present in microbial cells are extracellular enzymes namely proteolytic, amylolytic, lipolytic, cellulolytic, and pectinase, which can be extracted from A. niger and B. subtilis and are responsible for controlling the growth of AZNPR. The formation of AZNPR was characterised using different analyses. The FTIR shows absorption band located at ∼864 cm−1 that shows the interaction between Ag and ZnO. The XRD results showed the presence of crystalline AZNPR in the forms of hexagonal wurtzite ZnO and Ag. Microstructural and size examination showed that AZNPR was in the form of nanorods with homogeneous distribution with a size of rods in A. niger media 137.0 nm, while in B. subtilis media 197.4 nm. The Ag–ZnO nanorods revealed the ability to inhibit Candida albicans species, a fungus causing infectious disease, with an inhibition zone measuring 2.1–3.2 mm at 24 h.

Synthesis and characterization of calcium carbonate on three kinds of microbial cells templates

As is known, the formation of nanocrystals is influenced by the cells with which they interact. In particular, the same materials could exhibit different properties depending on the type of cells. In this work, we used three different types of microbial cells (Escherichia coli, Staphylococcus aureus, and Beer Yeast) as biological templates to control the crystallization of calcium carbonate particles before or after coated with several layers of polyelectrolyte films via Layer-by-Layer assembly and biomineralization process. The results showed that the resulting crystal types using different naked cells as templates all include calcite and vaterite, and the ratio of vaterite is higher. After encapsulating with polyelectrolyte, polyelectrolyte did not change the ratio of calcite to vaterite on the surface of E. coli and Staphylococcus aureus but yeast. Furthermore, it can weaken the intensity of vaterite and increase the proportion of calcite using the yeast as template. Differences in calcium carbonate crystal forms are related to the differences in cell wall components and cell secretion. So we mineralized calcium carbonate with the main components of the yeast cell wall (mannose oligosaccharide, β-glucan) and the Gram bacterial wall (peptidoglycan, lipopolysaccharide) directly, it was found that the composition of the cell wall did affect the crystal form and morphology of the calcium carbonate. This provides a reference for further study of the biomineralization mechanism and the selection of mineralization templates. Furthermore, this study provides some supplementary for understanding the natural mineralization process of CaCO3.

Segregating metabolic processes into different microbial cells accelerates the consumption of inhibitory substrates.

Different microbial cell types typically specialize at performing different metabolic processes. A canonical example is substrate cross-feeding, where one cell type consumes a primary substrate into an intermediate and another cell type consumes the intermediate. While substrate cross-feeding is widely observed, its consequences on ecosystem processes is often unclear. How does substrate cross-feeding affect the rate or extent of substrate consumption? We hypothesized that substrate cross-feeding eliminates competition between different enzymes and reduces the accumulation of growth-inhibiting intermediates, thus accelerating substrate consumption. We tested this hypothesis using isogenic mutants of the bacterium Pseudomonas stutzeri that either completely consume nitrate to dinitrogen gas or cross-feed the intermediate nitrite. We demonstrate that nitrite cross-feeding eliminates inter-enzyme competition and, in turn, reduces nitrite accumulation. We further demonstrate that nitrite cross-feeding accelerates substrate consumption, but only when nitrite has growth-inhibiting effects. Knowledge about inter-enzyme competition and the inhibitory effects of intermediates could therefore be important for deciding how to best segregate different metabolic processes into different microbial cell types to optimize a desired biotransformation.

The soil matrix increases microbial C stabilization in temperate and tropical forest soils

Microbial biomass represents a substantial source of labile C contributing to soil organic matter (SOM) maintenance. Microbial residues may associate with the soil matrix through a variety of mechanisms, reducing its bioavailability and increasing its persistence in soil. Our objective was to examine soil matrix effects on the stability of non-living microbial C inputs in two contrasting forest ecosystems by following microbial residues (Fungi, Actinobacteria, Gram-positive bacteria (Gm +), Gram-negative bacteria (Gm −)) into SOM fractions in a temperate forest in California (CA) and a tropical forest in Puerto Rico (PR) for 3 and 2 years, respectively. We isolated 3 SOM fractions: (i) free light fraction (FLF), (ii) occluded light fraction (OLF), and (iii) dense fraction (DF). Additionally, we characterized SOM fraction chemistry to infer quality and source of native fraction SOM. Our results showed greater stabilization as mineral-associated microbial C (i.e., as DF and OLF), compared with loose detrital C (i.e., FLF). There was no microbial group effect (i.e., differences in fraction C recovery among different microbial cell types). Our findings suggest that mineral association is more important for stabilizing non-living microbial C in soil than the cellular structure of the initial source of microbial inputs, with site specific edaphic factors as the major controllers of the amount of microbial residues stabilized.

Bioadsorption strategies with yeast molecular display technology.

Molecular display techniques using microbial cell surfaces have been widely developed in the past twenty years, and are useful tools as whole cell catalysts for various applications such as bioconversion, bioremediation, biosensing, and the screening system of protein libraries. Furthermore, different types of microbial cells among eukaryotic and prokaryotic strains have been investigated for their use in surface display technologies. Recently, several kinds of protein-displaying yeasts have been utilized as bioadsorbents in this platform technology. In particular, these trials have successfully expanded the possibility of applications to metal binding, affinity purification, and receptor-ligand interaction by using the yeast cell surface. In this mini review, we describe the general principles of molecular display technology using yeast cells and its applications, with a particular focus on bioadsorption.

The biological interpretation of metabolomic data can be misled by the extraction method used

The field of metabolomics is getting more and more popular and a wide range of different sample preparation procedures are in use by different laboratories. Chemical extraction methods using one or more organic solvents as the extraction agent are the most commonly used approach to extract intracellular metabolites and generate metabolite profiles. Metabolite profiles are the scaffold supporting the biological interpretation in metabolomics. Therefore, we aimed to address the following fundamental question: can we obtain similar metabolomic results and, consequently, reach the same biological interpretation by using different protocols for extraction of intracellular metabolites? We have used four different methods for extraction of intracellular metabolites using four different microbial cell types (Gram negative bacterium, Gram positive bacterium, yeast, and a filamentous fungus). All the quenched samples were pooled together before extraction, and, therefore, they were identical. After extraction and GC–MS analysis of metabolites, we did not only detect different numbers of compounds depending on the extraction method used and regardless of the cell type tested, but we also obtained distinct metabolite levels for the compounds commonly detected by all methods (P-value < 0.001). These differences between methods resulted in contradictory biological interpretation regarding the activity of different metabolic pathways. Therefore, our results show that different solvent-based extraction methods can yield significantly different metabolite profiles, which impact substantially in the biological interpretation of metabolomics data. Thus, development of alternative extraction protocols and, most importantly, standardization of sample preparation methods for metabolomics should be seriously pursued by the scientific community.

Ceramide activates JNK to inhibit a cAMP-gated K+ conductance and Cl- secretion in intestinal epithelia.

Sphingomyelinases (SMases) hydrolyze membrane sphingomyelin to ceramide and are expressed by diverse host and microbial cell types populating mucosal surfaces. Exogenous bacterial SMase acts on the basolateral membrane of polarized human intestinal epithelial cells to repress the cAMP-induced Cl(-) secretory response, but how this occurs is unknown. We show here that SMase acts by down-regulating a cAMP-gated basolateral membrane K(+) conductance. Neither phosphocholine, ceramide-1-phosphate, nor sphingosine-1-phosphate recapitulates this effect, indicating that ceramide production is the decisive factor. Basolaterally applied SMase induced the phosphorylation of c-Jun NH(2)-terminal kinase (JNK), and inhibition of JNK rescued the effect of SMase on cAMP-dependant secretion. SMase secreted by normal human fibroblasts specifically recapitulated the effect on cAMP-induced Cl(-) secretion, indicating that cell types inhabiting the subepithelial space can provide such an activity to the basolateral membrane of intestinal enterocytes in trans. Thus, conversion of sphingomyelin to ceramide in basolateral membranes of intestinal cells rapidly activates JNK to inhibit a cAMP-gated K(+) conductance and thereby attenuates Cl(-) secretion. These results define a novel lipid-mediated pathway for regulation of salt and water homeostasis at mucosal surfaces.

Cell Chromatography: Separation of Different Microbial Cells Using IMAC Supermacroporous Monolithic Columns

Supermacroporous monolithic columns with Cu(2+)-IDA ligands have been successfully used for chromatographic separation of different types of microbial cells. The bed of monolithic matrix is formed by a cryogel of poly(acrylamide) cross-linked with methylenebis(acrylamide) and has a network of large (10-100 microm) interconnected pores allowing unhindered passage of whole cells through the plain cryogel column containing no ligands. Two model systems have been studied: the mixtures of wild-type Escherichia coli (w.t. E. coli) and recombinant E. coli cells displaying poly-His peptides (His-tagged E. coli) and of w.t. E. coli and Bacillus halodurans cells. Wild-type E. coli and His-tagged E. coli were quantitatively captured from the feedstock containing equal amounts of both cell types and recovered by selective elution with imidazole and EDTA, with yields of 80% and 77%, respectively. The peak obtained after EDTA elution was 8-fold enriched with His-tagged E. coli cells as compared with the peak from imidazole elution, which contained mainly weakly bound w.t. E. coli cells. Haloalkalophilic B. halodurans cells had low affinity to the Cu(2+)-IDA cryogel column and could be efficiently separated from a mixture with w.t. E. coli cells, which were retained and recovered in high yields from the column with imidazole gradient. All the cells maintained their viability after the chromatographic procedure. The results show that chromatography on affinity supermacroporous monolithic columns is a promising approach to efficient separations of individual cell types.

Cell separation by expanded bed adsorption: use of ion exchange chromatography for the separation of E. coli and S. cerevisiae

In a wide variety of biotechnological and medical applications it is necessary to separate different cell populations from one another. A promising approach to cell separations is demonstrated to be the adoption of chromatographic techniques conducted in expanded beds. The high voidage between the adsorbent beads in an expanded bed allows for the efficient capture of particulate entities such as cells together with washing and subsequent elution without entrapment and loss. In addition, the combination of a gentle hydrodynamic environment, a high surface area and low mixing within the expanded bed make this technique highly favourable. A model system for the separation of two types of microbial cells using STREAMLINE DEAE adsorbent in expanded bed procedures has been investigated. The use of a less selective ligand such as an ion exchange group, which is often characterised by gentle elution procedures, has been investigated as an alternative to affinity ligands whose strong binding characteristics can result in harsh elution procedures with consequent loss of yield and cell viability. Expanded bed experiments have demonstrated selective and high capacity capture of cells from feedstocks containing either a single type of cell or as a mixture of cells of Saccharomyces cerevisiae and Eschericia coli. The capture, washing and elution phases of the separation have been studied with respect to capacity, selectivity and yield of released cells. In these procedures, separation of cell types is achieved by the presence of multiple equilibrium stages within the expanded bed. The results show the potential for carrying out cell separations in expanded beds as an alternative to immunomagnetic cell separations. The combination of these recently developed technologies promises to be a powerful, but economic technique for cell separations involving simple equipment that can readily be scaled up.

Surface properties of microbial cells probed at the nanometre scale with atomic force microscopy

Atomic force microscopy (AFM) was used to characterize, under water, the surface morphology and molecular interactions of two types of microbial cells: fungal spores (Phanerochaete chrysosporium) and bacteria (Lactococcus lactis), High-resolution deflection images showed that the spore surface was uniformly covered with patterns of rodlets that were several hundred nanometres in length and had a periodicity of similar to 10 nm, Such surface organization was not detected on the bacterial surface, which showed a sponge-like structure. Force-distance curves revealed very different molecular interactions for the two microorganisms: upon approach, no significant curvature was seen in the contact region for spores, contrary to bacteria, pointing to a difference in cell softness; and upon retraction, no adhesion forces were detected on spores but multiple unbinding events and elongation forces attributed to macromolecular bridging were observed on bacteria. These results show that AFM is a powerful tool for probing the surface properties of native microbial cells on the nanometre scale. Copyright (C) 2000 John Wiley & Sons, Ltd.

Microfiltration and Ultrafiltration of Milk: Some Aspects of Fouling and Cleaning

Milk filtration using membranes is one of the most effective ways of separating fat, proteins and many types of microbial cells without the use of heat. This investigation was undertaken to determine the main factors responsible for the decline in permeate flux during milk processing and to study the fouling phenomena. There are a variety of fouling mechanisms, which may or may not be significant depending upon the combined characteristics of the membrane, feed stream and operating conditions. In this study, the performance of a microfiltration membrane was compared with an ultrafiltration membrane in terms of fouling and cleaning characteristics using a cross flow membrane rig. Atomic Force Microscopy was employed to explore the fouling phenomena. Factors of importance for membrane cleaning such as temperature, transmembrane pressure, circulation time and cleaning performance were also investigated.

Small-Scale DNA Sample Preparation Method for Field PCR Detection of Microbial Cells and Spores in Soil.

Efficient, nonselective methods to obtain DNA from the environment are needed for rapid and thorough analysis of introduced microorganisms in environmental samples and for analysis of microbial community diversity in soil. A small-scale procedure to rapidly extract and purify DNA from soils was developed for in-the-field use. Amounts of DNA released from bacterial vegetative cells, bacterial endospores, and fungal conidia were compared by using hot-detergent treatment, freeze-thaw cycles, and bead mill homogenization. Combining a hot-detergent treatment with bead mill homogenization gave the highest DNA yields from all three microbial cell types and provided DNA from the broadest range of microbial groups in a natural soil community. Only the bead mill homogenization step was effective for DNA extraction from Bacillus globigii (B. subtilis subsp. niger) endospores or Fusarium moniliforme conidia. The hot-detergent-bead mill procedure was simplified and miniaturized. By using this procedure and small-scale, field-adapted purification and quantification procedures, DNA was prepared from four different soils seeded with Pseudomonas putida cells or B. globigii spores. In a New Mexico soil, seeded bacterial targets were detected with the same sensitivity as when assaying pure bacterial DNA (2 to 20 target gene copies in a PCR mixture). The detection limit of P. putida cells and B. globigii spores in different soils was affected by the amount of background DNA in the soil samples, the physical condition of the DNA, and the amount of DNA template used in the PCR.

Terpenes in sponge cell membranes: Cell separation and membrane fractionation studies with the tropical marine spongeAmphimedon sp.

AbstractThe differing sponge and symbiotic microbial cell types in the tropical marine spongeAmphimedon sp. were fractionated according to density, investigated by electron microscopy, and analyzed by high‐performance liquid chromatography and nuclear magnetic resonance for the presence of the terpene metabolite diisocyanoadociane (1) and Δ5,7‐sterols (2–7). A sample of whole sponge was dissected into superficial ectosome and deeper choanosome. The superficial tissue was found to be enriched in sterol relative to choanosome; however, extracts from both tissues contained terpene. Dissociation of whole sponge followed by Ficoll density gradient fractionation showed that there are two chemically distinct types of sponge cells inAmphimedon sp.—small non‐nucleolated cells of low density contain terpene 1 together with sterols, while larger nucleolated cells contain significant levels of terpene, but only traces of sterol. Membrane fractionation studies were undertaken to establish whether the terpene components were located specifically in the cell membranes of these two cell types. A membrane vesicle pellet spun down at 100,000×g from small sponge cells contained sterols, but only traces of terpene, whereas the membrane vesicle preparation from heavier cells contained both terpenes and sterols. Subsequently, the presence of terpenes together with sterols was demonstrated in a membrane vesicle preparation of purity &gt;90% prepared from bacteria‐free sponge cells. These results provide the first experimental evidence that terpenes are associated with sponge cell membranes, where they may function as structural components.

Introduction to Extracellular Enzymes: From the Ribosome to the Market Place

This chapter discusses the general properties of extracellular enzymes. It describes rhe features of extracellular enzymes that are common to their synthesis, to their manipulation, in their stability, and to the entire spectrum of the reactions that they catalyze. Future advances in the application of extracellular enzymes and other enzymes are also presented. The extracellular enzymes are, majorly, hydrolases are important in basic studies because they are produced in high concentrations, they are easy to purify, they are easy to assay, they are stable, and they have relatively low molecular weights. Microbially produced extracellular enzymes are of ecological significance. They hydrolyze the macromolecules that are too large to be transported into many types of microbial cells. In contrast to the many labile enzymes, extracellular enzymes survive fairly adverse conditions. Many are able to tolerate high temperatures and survive for relatively long periods of time in soil, the open sea, the sediments of oceans and freshwater lakes, and even in activated sludge.

Deoxyribonucleic acid content of morphologically different cell-types of Ophiostoma multiannuatum.

DURING recent years a number of investigations have been published on the deoxyribonucleic acid (DNA) content of different types of microbial cells. Lark and Maaloe1 have thus studied the synthesis of DNA in normal and temperature-synchronized cultures of Salmonella, and Petras2 has determined the nucleic acid content of normal and filamentous cells of Proteus vulgaris. Wachter and Spoerl3 were unable to detect significant differences in the nucleic acid content of different cell forms of Ustilago sphaerogena.