Inorganic Salt Medium Research Articles

Comparative analysis of membranous proteomics of Shewanella decolorationis S12 grown with azo compound or Fe (III) citrate as sole terminal electron acceptor

Shewanella decolorationis S12 is capable of carrying out anaerobic respiration using azo dyes and Fe (III) citrate as electron acceptors. In the present study, proteomic techniques including two-dimensional gel electrophoresis (2-DE) and matrix-assisted laser desorption/ionization time-of-flight/time-of-flight mass spectrometry were used to analyze the similarity and the dissimilarity of the membrane proteins isolated from strain S12 cells grown in amaranth or Fe (III) citrate with defined inorganic salt medium. The cells of strain S12 grown under a saturated dissolved oxygen condition served as controls. This is the first work that made the comparative analysis of cell membranous proteomics of strain S12 grown with azo compound or Fe (III) citrate as a sole terminal electron acceptor. The results showed that most of the membrane proteins of strain S12 under azo respiration are similar to those under Fe (III) respiration, but dissimilar from those of oxygen-grown cells. FdnH and FrdB were expressed specifically in azo respiration. NqrA-2, DctP, and hypothetical protein SO_4719 showed relative overexpression in azo respiration compared with Fe (III) respiration. OmpA family protein SO_3545 was detected to be specific to Fe (III) respiration. Furthermore, ArgF, SdhA, and HoxK were expressed markedly in both amaranth- and Fe (III) citrate-grown cultures compared with oxygen-grown cultures.

Production of Trametes gallica lignocellulases for wheat straw degradation

Trametes gallica (T. gallica) is a high producer of lignin-degrading enzymes including laccases, lignin peroxidases (LiPs), manganese-dependent peroxidases (MnPs), and hemicellulases (Hcels). The enzyme activities could peak at an early stage of fermentation. The activities of laccases and LiPs were high in high-nitrogen, low–carbon, and high inorganic salt media, while the activities of MnPs, and Hcels were the high in low-nitrogen, high–carbon, and high inorganic salt medium. It was found that T. gallica caused 34.4% mass losses after 20 days, 46.7% after 30 days, and 70.1% after 60 days, and at the same time T. gallica was able to degrade lignin at an early stage of solid fermentation. Based on these results, T. gallica may be a strain candidate for biopulping in the paper industry.

Isolation and Identification of a Strain of Aspergillus Tubingensis With Deoxynivalenol Biotransformation Capability

Deoxynivalenol (DON) is one of the most common contaminants of various foodstuffs. A biotransformation system was used in order to lessen the toxicity of DON. A strain of Aspergillus (NJA-1) was isolated from soil and cultured in an inorganic salt medium containing DON. Bt2a/Bt2b primers were used to amplify the β-tubulin gene of NJA-1. Sequence analysis the PCR product and morphology observation indicated that NJA-1 belonged to Aspergillus tubingensis (aerobic fungi). The DNA sequence information of the PCR product was deposited in GenBank (accession number DQ9025790). The DNA sequence had 99% similarity to the Aspergillus tubingensis accession number AY820009. An unknown compound in NJA-1 showed the ability to convert DON into another product. The molecular weight of the bioconversion product was 18.1 D (H2O) larger than that of DON. The analysis showed that DON could be hydrolyzed by NJA-1. The mean DON biotransformation rate was 94.4% after two weeks of cultivation. The finding presents a new method for DON biotransformation.

Isolation, Identification, and Degradation Characteristics of Phenazine-1-Carboxylic Acid–Degrading Strain Sphingomonas sp. DP58

A phenazine-1-carboxylic acid (PCA)-degrading bacterium, strain DP58, was isolated from pimiento rhizosoil. Based on morphology, physiologic tests, 16S rDNA sequence, and phylogenetic characteristics, it was identified as Sphingomonas sp. The PCA-degradation experiments were conducted both in Luria-Bertani and inorganic salt medium at 28 degrees C. The relationship between bacterium growth and PCA degradation suggested that strain DP58 could use PCA as the sole source of carbon and nitrogen and was able to completely degrade PCA in 40 hours. Newly isolated strain DP58 represents the first bacterium that can degrade PCA.

Cryptic freshwater amoeba species in the bottom sediments of Nivå Bay (Øresund, Baltic Sea)

An aquarium containing a portion of freshly collected brackish-water sediment from Nivå Bay (Øresund, Baltic Sea) was sampled to determine the species of amoebae present and refilled with inorganic salt medium to achieve freshwater salinity. After 2 months incubation, the diversity of amoebae was again studied, and the salinity was restored to the original level. The aquarium was incubated for a further 2 months and the amoeba fauna was studied for the last time. A number of freshwater species appeared in the sample after the first salinity shift, while some marine species disappeared. Most marine species did not re-appear after the salinity in the aquarium was restored, but one marine species not noted previously was recorded. The experiment illustrates the presence of ‘cryptic diversity’ of amoebae in natural habitats and demonstrates that laboratory manipulation of the salinity of a sample prior to inoculation may achieve an increased recovery of species from a brackish-water habitat.

Isolation and characterization of Pseudomonas sp. strain HF-1, capable of degrading nicotine

A nicotine-degrading bacterium, strain HF-1, was isolated from tobacco waste-contaminated soil and identified as a member of Pseudomonas sp. based on morphology, physiological tests, Vitek system (GN+), Biolog GN, 16S rDNA sequence and phylogenetic characteristics. The thermal denaturation test indicated that the G + C content of the DNA of HF-1 was 62.7 mol%. The relationship between growth and nicotine degradation of the isolate suggested that strain HF-1 could utilize nicotine as sole source of carbon, nitrogen and energy. Viridescent pigment was observed during nicotine degradation by strain HF-1. The isolate grew optimally at 30 °C, initial pH 6.5–7.5 and 1.3 g l −1 of nicotine concentration in the nicotine inorganic salt medium, which is basically consistent with degradation of nicotine by the isolate. Strain HF-1 could degrade 99.6% of nicotine under the optimized incubation conditions for 25 h monitored by high-performance liquid chromatography. This study demonstrates that Pseudomonas sp. strain HF-1 had strong ability to degrade nicotine, and may be useful for bioremediation of environments contaminated by tobacco waste.

Solar Gasification of Biomass: A Molten Salt Pyrolysis Study

A novel solar process and reactor for thermochemical conversion of biomass to synthesis gas is described. The concept is based on dispersion of biomass particles in a molten inorganic salt medium and, simultaneously, absorbing, storing and transferring solar energy needed to perform pyrolysis reactions in the high-temperature liquid phase. A lab-scale reactor filled with carbonates of potassium and sodium was set up to study the kinetics of fast pyrolysis and the characteristics of transient heat transfer for cellulose particles (few millimeters size) introduced into the molten salt medium. The operating conditions were reaction temperatures of 1073–1188 K and a particle peak-heating rate of 100 K/sec. The assessments performed for a commercial-scale solar reactor demonstrate that pyrolysis of biomass particles dispersed in a molten salt phase could be a feasible option for the continuous, round-the-clock production of syngas, using solar energy only.

Heterotrophic nitrification in an acid forest soil: isolation and characterisation of a nitrifying bacterium

Bacteria and fungi were isolated from an acid forest soil in which nitrification occurred via a heterotrophic pathway. Enrichment of soil in a liquid inorganic salts medium, containing β-alanine as the sole source of C and N, led to formation of NO 2 − and NO 3 −. In pure culture, β-alanine was not a suitable substrate for nitrification by any of the isolates, but did support nitrification when one bacterium ( B D) was co-cultured with a fungus. This bacterium was gram-positive and rod-shaped and identified provisionally as an Arthrobacter sp. The bacterium B D was able to nitrify ammonium acetate and, to a lesser extent peptone, in pure culture. Nitrification of ammonium acetate was greater in sterile soil solution than in defined media of inorganic salts. From a less reduced form of N, α-ketoglutaric oxime supported the highest rates of nitrification, but nitrification of pyruvic and ketobutyric oximes was at levels lower than from reduced N. The organism was able to survive and nitrify at pH 3, and despite its isolation from a very acidic environment, at pH≤10. It is proposed that a metabolic product of β-alanine produced by a non-nitrifying microorganism provided a suitable substrate for the nitrifying bacterium.

Effects of prey abundance and light intensity on the mixotrophic chrysophyte Poterioochromonas malhamensis from a mesotrophic lake

1. Previous studies of mixotrophy in the flagellate Poterioochromonas malhamensis (Chrysophyceae) were performed on strains that had been in culture for > 30 years. This study aims to compare mixotrophy in a cultured strain with one recently isolated from a mesotrophic lake (Lacawac) in Pennsylvania, U.S.A.2. P. malhamensis from the lake exhibited a nutritional flexibility similar to that of the culture strain, growing phototrophically but inefficiently in comparison to other nutritional modes (growth rate (μ) = 0.015 h−1). Supplementing an inorganic salts medium with 1 mM glucose resulted in a doubling of μ to 0.035 h−1 and 0.033 h−1 in the light and the dark, respectively. Addition of an algal prey, Nannochloris, to the inorganic salts medium increased growth to rates similar to those observed with glucose. Maximum growth of the lake strain, 0.095 h−1, was achieved when bacteria was supplied as food. During growth on bacteria, cellular chlorophyll a (Chl a) decreased from 140 fg cell−1 to 10 fg cell−1 over 22 h when cultured either in the light or dark. In illuminated cultures, cell‐specific Chl a concentration recovered to 185 fg cell−1 after bacteria became limiting.3. In contrast to the cultured strain, however, the lake isolate exhibited an inverse relationship between light intensity and ingestion rate. Calculated grazing rates, based upon the ingestion of fluorescently labeled bacteria, were 3.2, 5.2 and 9.4 bacteria flagellate−1 h−1, for P. malhamensis incubated in high light, low light and darkness, respectively. Phagotrophy is thus influenced by a light regime in this predominately heterotrophic mixotroph.

Degradation of arsenobetaine to inorganic arsenic by bacteria in seawater

The substances suspended in seawater were fractionated by membrane filtration into three fractions. Fraction 1 was collected on a membrane filter of 0.22 µm pore-size, fraction 2 on a 5 µm pore-size and fraction 3 on 0.22 µm pore-size from the filtrate passed through the 5 µm membrane filter. Arsenobetaine was incubated with each of these fractions in two media (ZoBell 2216E and a solution of inorganic salts) at 25 °C in the dark under aerobic conditions. The mixture added with fraction 3 was considered to contain only bacteria. In every case, in the inorganic salt medium, inorganic arsenic(V) was derived from arsenobetaine via trimethylarsine oxide. In the ZoBell medium, arsenobetaine was not degraded to inorganic arsenic, although trimethylarsine oxide was derived in every case. We conclude that the degradation of arsenobetaine to trimethylarsine oxide or inorganic arsenic can be accomplished in seawater by bacteria alone.

Degradation of a tetramethylarsonium salt by microorganisms occurring in sediments and suspended substances under both aerobic and anaerobic conditions

AbstractMicrobial degradation of a tetramethylarsonium salt during incubation at 25°C was investigated under both aerobic and anaerobic conditions. Two media (1/5 ZoBell 2216E and inorganic salt medium), added with the sediments or suspended substances as the sources of the microorganisms, were used. Degradation of the tetramethylarsonium salt occurred only in the ZoBell medium: under anaerobic conditions, trimethylarsine oxide and dimethylarsinic acid were derived with the sediments, and dimethylarsinic acid with the suspended substances, the salt degrading more rapidly with the former than with the latter. Small amounts of two metabolites, trimethylarsine oxide and inorganic arsenic(V), was also derived in the aerobically incubated ZoBell medium added with the suspended substances. This result means that the tetramethylarsonium salt is degraded to inorganic arsenic, which is the starting material for arsenic circulation in marine ecosystems, via trimethylarsine oxide and dimethylarsinic acid.

Effects of chemical speciation in growth media on the toxicity of mercury(II).

The toxicity of metals, including mercury, is expressed differently in different media, and the addition of soluble organics to the growth medium can have a significant impact on bioassay results. Although the effect of medium composition on metal toxicity is generally attributed to its effect on metal speciation (i.e., the chemical form in which the metal occurs), the importance of individual metal-ligand species remains largely unclear. Here, we report the results of a study that investigated, both experimentally and from a modeling perspective, the effects of complex soluble organic supplements on the acute toxicity (i.e., 50% inhibitory concentration [IC50]) of mercury to a Pseudomonas fluorescens isolate in chemically well-defined synthetic growth media (M-IIX). The media consisted of a basal inorganic salts medium supplemented with glycerol (0.1%, vol/vol) and a variety of common protein hydrolysates (0.1%, vol/vol), i.e., Difco beef extract (X = B), Casamino Acids (X = C), peptone (X = P), soytone (X = S), tryptone (X = T), and yeast extract (X = Y). These were analyzed to obtain cation, anion, and amino acid profiles and the results were used to compute the aqueous speciation of Hg(II) in the media. Respirometric bioassays were performed and IC50s were calculated. Medium components varied significantly in their effects on the acute toxicity of Hg(II) to the P. fluorescens isolate. IC50s ranged from 1.48 to 14.54 micrograms of Hg ml-1, and the acute toxicity of Hg(II) in the different media decreased in the order M-IIC >> M-IIP > M-IIB >> M-IIT > M-IIS >>> M-IIY.(ABSTRACT TRUNCATED AT 250 WORDS)

Degradation of arsenobetaine to inorganic arsenic by the microorganisms occurring in the suspended substances

Abstract 1. 1. Arsenobetaine-containing growth media (ZoBell 2216E and a solution of inorganic salts) were incubated with suspended substances as a source of marine microorganisms. 2. 2. The degradation of arsenobetaine to inorganic arsenic was shown in the inorganic salts medium, being found for the first time with respect to the microorganisms occuring in them. 3. 3. Trimethylarsine oxide and dimethylarsinic acid were also shown as metabolites in both the media. 4. 4. These results suggest the microbial degradation of arsenobetaine in the water column.

Acid Extrusion by the Ciliate Protozoan Tetrahymena pyriformis, and Activation of a Quiescent Na<sup>+</sup>/H<sup>+</sup> Exchanger by CuSO<sub>4</sub>

In the extracellular pH (pHo) range 6.5–7.25, intracellular pH (pHi) in Tetrahymena pyriformis was 0.5–1 pH unit higher than expected if H+ were passively distributed across the cell membrane. Average H+ efflux from cells suspended in an inorganic salt medium containing glucose was 7.6 ± 0.61 nmol/mg dry weight/min ( ± SEM, n = 21) at pH0 6.8. H+ efflux was unaffected by sodium depletion, 0.4 mM amiloride (inhibitor of the Na+/H+ exchange system), 0.1 mM DIDS (inhibitor of anion exchange systems) and by 6 mM cinnamate (inhibitor of lactate transport). Addition of low concentrations of CuSO4 (about 5 µM) induces an amiloride-sensitive Na+ influx and an amiloride-sensitive and Na+-dependent increase in the H+ efflux. It is concluded that pH regulatory systems known from animal cells are inactive (or absent) in Tetrahymena. The Na+/H+ exchange system can, however, be activated with low concentrations of the heavy metal salt CuSO4, suggesting that this system is present, but silent under normal conditions.

Conversion of arsenobetaine by intestinal bacteria of a mollusc Liolophura japonica chitons

AbstractThe intestinal micro‐organisms of Liolophura japonica chitons converted arsenobetaine [(CH3)3As+CH2COO−] to trimethylarsine oxide [(CH3)3AsO] and dimethylarsinic acid [(CH3)2AsOOH] in the arsenobetaine‐containing 1/5 ZoBell 2216E medium under aerobic conditions, no conversion being observed in an inorganic salt medium. This conversion pattern of arsenobetaine → trimethylarsine oxide ← dimethylarsinic acid was comparable with that shown by the microorganisms associated with marine macroalgae. On the other hand, no conversion was observed in either medium under anaerobic conditions.

Determination of the labile species of zinc by anodic stripping staircase voltammetry, with special reference to correlation with the toxicity to tetrahymena

Anodic stripping staircase voltammetry (ASSV) has been tested as a method to determine the concentration of “free” ions and very labile complexes of zinc. These species are thought to be primarily responsible for the toxic effect of zinc on the ciliated protozoan Tetrahymena pyriformis. ASSV and toxicological experiments were performed in an inorganic salt medium and the effects of Cu interference were studied. Even though the ASSV results were encumbered with problems, the results agreed well with the toxicological effects. In contrast, calculations based on the solubility product of Zn 3 (PO 4) 2·4H 2O could lead to erroneous results because kinetic and other effects result in very slow precipitation of zinc phosphate at the concentration levels in the salt medium used. In this medium there is a dose-dependent effect of zinc on Tetrahymena which is in agreement with the ASSV data, which indicate that all the zinc is in a labile form. The study emphasizes the importance of using experimental determinations in preference to theoretical models, which may predict quite erroneous results.

Effects of medium composition and light on formation of apothecia and sclerotia by Pyronema domesticum

Pyronema domesticum (Sow.) Sacc. was cultured in a 12 h light: 12 h dark cycle and in the dark on water agar; an inorganic salts medium (Claussen's agar); Claussen's agar supplemented with casein hydrolysate, biotin, thiamine, asparagine, glycine, or urea; and media containing a variety of natural materials, either supplemented or not with dextrose or another carbohydrate. Apothecial formation was favored by illumination, while sclerotial formation was favored by darkness. Maximum production of apothecia and sclerotia occurred on low-carbohydrate media supporting scant to moderate mycelial growth but was prevented on medium with a high carbohydrate concentration (20 g/L). Large numbers of well-developed apothecia formed on dilute media containing only inorganic nutrients (Claussen's agar), a small amount (3.0 g/L) of casein hydrolysate, or the extract from 20 g potatoes/L. Fewer incompletely developed apothecia formed on 2% water agar. Apothetical production was depressed or prevented by the addition of asparagine, glycine, urea, biotin, or thiamine to Claussen's agar. Sclerotia formed in maximum numbers on rabbit food agar, vegetable juice agar, and on dilute potato extract agar. Fewer sclerotia were produced on Claussen's agar.

Microbial interactions in heterotrophic nitrification

An Arthrobacter sp. capable of extensive nitrification was isolated from a eutrophic lake sediment employing inorganic salts medium with acetamide as the carbon source. This heterotrophic nitrifier was found to be closely associated with a Corynebacterium sp. both in growth and in nitrification. When the Arthrobacter sp. was jointly cultured with the Corynebacterium sp. in medium containing ammonium ion, acetate, and inorganic salts, the concentrations of nitrification products (nitrite and nitrate) increased approximately 10-fold. This stimulatory interaction was also determined in filter-sterilized sediment water samples amended with ammonium ion and acetate. Although both organisms failed to grow singly in media containing 1 mg/mL of nitrite N and of acetaldoxime N, they grew well in both media when cultured jointly. Nitrification, however, occurred only in the acetaldoxime medium. This is the first reported instance of mutualistic relationships in heterotrophic nitrification arid appears to be significant to our understanding of nitrogen transformation in lacustrine environments.

Immobilization of yeast cells with high β-galactosidase activity

K. lactis batch growth conditins were optimized for high B-galactosidase content using a modified inorganic salt medium with 1 % lactose at 300C. The pH was found to be a suitable indicator for the optimum harvest time. Cell wall permeabilization by Triton yielded β-galactosidase activity of up to 966 LAU (g cell)-1. The effect of Triton treatment was documented by SEM pictures of the cells. The cells were immobilized in polyurethane foam and used in a continuous plug-flow reactor with a half-life time of approximately 3 days. It was shown that both the free as well as the immobilized cells utilize glucose in a follow-up reaction and, therefore, kinetic measurements based on glucose concentrations alone are not sufficient to evaluate true kinetic parameters.

Yeast cells with high β-galactosidase activity and their immobilization

The batch growth conditions of K. lactis were optimized for high β-galactosidase content using a modified inorganic salt medium with 1% lactose at 30 °C and pH as an indicator for the harvest time. Cell β-galactosidase activity of up to 966 LAU (g cell) −1 was achieved when the cell wall was permeabilized by Triton. The cells in batch operation tended to utilize glucose when it accumulated rather than lactose. The immobilized cells should be therefore used in a continuous plug flow reactor. The experiments with a 50 ml column reactor filled by the cells immobilized in polyurethane foam showed a good activity with no leakage of cells and a half-life time of approximately 3 d.