Result Of Microbial Activity Research Articles

Metabolome and Microbiome Analysis to Study the Flavor of Summer Black Tea Improved by Stuck Fermentation.

Tea is the most popular and widely consumed beverage worldwide, especially black tea. Summer tea has a bitter and astringent taste and low aroma compared to spring tea due to the higher content of polyphenols and lower content of amino acids. Microbial fermentation is routinely used to improve the flavor of various foods. This study analyzed the relationship between the quality of black tea, metabolic characteristics, and microbial communities after microbial stuck fermentation in summer black tea. Stuck fermentation decreased the bitterness, astringency sourness, and freshness, and increased the sweetness, mellowness, and smoothness of summer black tea. The aroma also changed from sweet and floral to fungal, with a significant improvement in overall quality. Metabolomics analysis revealed significant changes in 551 non-volatile and 345 volatile metabolites after fermentation. The contents of compounds with bitter and astringent taste were decreased. Sweet flavor saccharides and aromatic lipids, and acetophenone and isophorone that impart fungal aroma showed a marked increase. These changes are the result of microbial activities, especially the secretion of extracellular enzymes. Aspergillus, Pullululanibacillus, and Bacillus contribute to the reduction of bitterness and astringency in summer black teas after stuck fermentation, and Paenibacillus and Basidiomycota_gen_Incertae_sedis contribute positively to sweetness. In addition, Aspergillus was associated with the formation of fungal aroma. In summary, our research will provide a suitable method for the improvement of tea quality and utilization of summer tea, as well as provide a reference for innovation and improvement in the food industry.

The development of alginate-based amperometric nanoreactors for biochemical profiling of living yeast cells

This study describes the development of a one-pot electrochemical miniaturized system for simultaneous cultivation and monitoring of the oxidative status of living cells. This system consisted of screen-printed electrodes modified by electroplated Pd-NPs as an electrocatalyst (i) and living yeast cells (Saccharomyces cerevisiae) (ii) immobilized on the cytocompatible alginate layer (iii).Briefly, during the course of electrochemical investigations a novel electroactive compound methylhydrazine derivative as a secondary metabolite and result of microbial activity was found in yeast cells and used as a signaling molecule for their biochemical profiling. Under the optimized experimental conditions the signal corresponding to the found electroactive secondary metabolite formed in medium of living cells was measured without sample collecting, transport, storage or pre-treatment steps (i.e. extraction, pre-concentration, chemical derivatization or labeling). The electrochemical dependencies, which were derived by a miniaturized electroanalytical system, were fully validated in a conventional three-electrode system under inert atmosphere (Ar) and in the presence of oxygen (air, O2).It is believed that the proposed one-pot nanoreactors serving simultaneously as nanofermenters and amperometric detectors for the quantification of secondary metabolites formed in medium of living cells can significantly enhance the understanding of ongoing fermentation processes in the future and our knowledge on the biochemistry of yeasts.

Halophiles and Their Vast Potential in Biofuel Production.

Global warming and the limitations of using fossil fuels are a main concern of all societies, and thus, the development of alternative fuel sources is crucial to improving the current global energy situation. Biofuels are known as the best alternatives of unrenewable fuels and justify increasing extensive research to develop new and less expensive methods for their production. The most frequent biofuels are bioethanol, biobutanol, biodiesel, and biogas. The production of these biofuels is the result of microbial activity on organic substrates like sugars, starch, oil crops, non-food biomasses, and agricultural and animal wastes. Several industrial production processes are carried out in the presence of high concentrations of NaCl and therefore, researchers have focused on halophiles for biofuel production. In this review, we focus on the role of halophilic microorganisms and their current utilization in the production of all types of biofuels. Also, the outstanding potential of them and their hydrolytic enzymes in the hydrolysis of different kind of biomasses and the production of biofuels are discussed.

Sulfide mineral dissolution microbes: Community structure and function in industrial bioleaching heaps

Heap bioleaching is one of the most clean and economical processes for recovery of low-grade and complex ores, because the sulfide minerals are natural habitats for acidophiles capable of iron- and sulfur-oxidation. The most exciting advances in heap bioleaching are occurring in the field of microbiology, especially with the development of advanced molecular biology approaches. These chemolithotrophic microorganisms living in the acid mine environment fix N2 and CO2 and obtain energy for growth from soluble ferrous iron and reduced inorganic sulfur compounds during oxidation of sulfide minerals. The ferric iron as oxidant and sulfuric acid are a result of microbial activity and provide favorable conditions for the dissolution of sulfide minerals. Various microbial consortia were applied successfully in commercial bioleaching heaps around the world, and microbial community and activity were adapted related to the local climatic conditions, ore characteristics and engineering configuration. This review focuses on diversity of bioleaching microbes, their role in heap bioleaching processes, their community structure and function in industrial heaps and the relation to the ore characteristics and the engineering configuration, to give implications for optimizing leaching efficiency of heap bioleaching.

Halitosis: A Review of Etiology and Management

Bad breath or Oral is a frequent or persistent unpleasant odor of breath. It is a common and multi-factorial condition. In around 85 percent of cases, halitosis is the result of microbial activity in the mouth. In patients with healthy periodontal tissue, causative bacteria deposit on the dorsal tongue. The basic psychopathological process is manifested by the release of substances caused by degradation due to bacterial activity, such as volatile sulfur compounds (VSC), organic acids, and products of metabolic activity. Factors contributing to the overgrowth of causative bacteria include decreased salivary flow and stress. This presentation reviews the current knowledge of etiology and different aspects of its diagnosis and treatment.

Column Test Studies of Ochre Biofilm Formation in Geotextile Filters

This paper presents a study of ochre formation in geotextile filters. Ochre is a substance found sticking to solid surfaces of drainage systems that may cause clogging. The accumulation of such materials in a drainage system may have undesirable implications, such as a decrease in drainage flow capacity and an increase in soil pore pressure; instability of soil masses and retaining systems; and alteration of the direction of flow and development of pipes. Ochre formation is the result of microbial activities on iron compounds naturally found in seepage water. Even though geotextiles have been widely used in drainage systems, very few studies have considered ochre formation in the tests. Laboratory column filter tests were conducted to simulate the ochre formation process under similar conditions to those in geotechnical works and to assess the long-term performance of a geotextile. Ochre is most likely to be formed at an aerated/nonaerated interface in the filter. In order to obtain this condition, the underneath face of the filters was opened to the atmosphere. Three different types of geotextile—nonwoven polyester, nonwoven polypropylene, and woven polypropylene—were used in the tests. Control tests were also conducted with a sand filter to provide a basis for comparison. Hydraulic conductivity changes and iron retention within the permeameters were monitored throughout the tests. Ochre was formed under the presence of iron ions and iron bacteria. During the test period, the filters were not clogged to such an extent as to induce a global reduction in the permeability of the drainage system. Nevertheless, at the end of the tests a considerable amount of ochre was found in all filters and there was a significant variation in the permeability of the geotextile filters when tested in isolation. These studies may contribute to discovering whether ochre can be considered as a biofilm, evaluating the clogging potential and defining mitigating measures.

Benzidine transformation processes in natural sediments

Aromatic amines, such as benzidine and 3,3'-dichlorobenzidine, are chemicals used in the pigment and dye processes. Release of these compounds into the environment is important because of their carcinogenic and toxic nature. In the present study, the sediment and water samples were collected from Lake Macatawa (Holland, MI, USA) and subsequently spiked with benzidine. The grain size distribution of the sediment samples investigated here ranged in composition from sandy to silty-clay sediment types. The sediment-water systems spiked with benzidine were incubated under anaerobic conditions at 4, 15, and 23 degrees C for 211 d. Degradation of benzidine was observed over the time-course analysis of the sediment-water mixtures. Three possible metabolites (aniline, 2-ethyl-1-hexanol, and 1-amino-2-hexene) were observed during this investigation as a result of gas chromatography/mass spectrometry and liquid chromatography/mass spectrometry. No metabolites were observed in autoclaved bottles, suggesting that the transformation of benzidine in the sediment-water mixtures was the result of microbial activity. From sediment-water distribution experiments, benzidine demonstrated higher sorption affinity for the different sediment phases than its degradation product, aniline. Therefore, microbially mediated transformation of benzidine to aniline is expected to yield a greater total concentration of the more mobile compound, aniline, in the water phase and a greater possibility for transport of aniline in the water phase.

Carious pulpitis: microbiological and histopathological considerations.

Dental caries is the result of microbial activities that induce the progressive localised destruction of teeth. Without treatment, this eventually results in infection of the dental pulp and surrounding periapical tissues. Although the bacteria responsible for caries initiation and early caries progression have been extensively studied, the microbiology of dentine caries reportedly shows considerable diversity and the associated microflora has not yet been fully identified. A search of the literature shows that few studies have analysed the microbiology of deep caries or examined the relationship between this microflora and the histopathology of chronic pulpitis in symptomatic teeth. The majority of the studies investigating the microbiology of carious dentine have used traditional culture methodology that has been reported to be fraught with difficulties and to underestimate the microbial populations. However, recent work using new technology in the form of Polymerase Chain Reaction (PCR) has shown potential by enhancing the identification and quantification of bacteria from complex environments. Application of this technology to carious dentine has identified an environment dominated by anaerobic organisms and containing significant numbers of Gram-negative bacteria that have been strongly implicated in endodontic infections subsequent to carious pulpitis. Examination of the histopathology of pulp sections from teeth extracted as a result of carious pulpitis showed pulpal reactions ranging from minimal inflammation to marked inflammatory infiltration of the pulp tissue. Of interest, were hard and soft tissue pathologic changes noted in the pulp tissues resulting from the combined effects of the carious microorganisms and the host tissue response. Improved knowledge of the microbial species associated with pulpitis could create the potential for development of diagnostic tools and restorative materials with appropriate antimicrobial properties.

Alteration of hyaloclastites in the HSDP 2 Phase 1 Drill Core 1. Description and paragenesis

The core from the Hawaii Scientific Drilling Project 2 Phase 1 provides a unique opportunity for studying the low‐temperature alteration processes affecting basalt in suboceanic‐island environments. In hyaloclastites, which make up about one half of the lower 2 km of this core (the portion that accumulated below sea level), these processes have resulted in zones of incipient, smectitic, and palagonitic alteration. The alteration of sideromelane in these hyaloclastites has four distinct outcomes: dissolution, replacement by two different textural varieties of smectite (i.e., reddened and green grain‐replacive), and conversion to palagonite. All samples show evidence of the incipient stage of alteration, suggesting that every sample passed through that zone. However, most samples that show palagonitic alteration do not also show evidence of smectitic alteration and vice versa, suggesting these two outcomes represent divergent paths of alteration. Incipient alteration (1080 to 1335 m depth) includes fracturing and mechanical reduction of porosity from 40–45% to about 20–30%; growth of one form of pore‐lining smectite; dissolution of sideromelane; and formation of sideromelane‐grain replacements consisting of Fe‐hydroxide‐strained smectite, titaniferous nodules, and tubules. DNA‐specific stains and morphological features indicate that tubules are the result of microbial activity. Smectitic alteration (1405 to 1573 m) includes growth of a second variety of pore‐lining smectite, pore‐filling and grain‐replacing smectite, and cements of phillipsite and Ca‐silicate minerals. Palagonitic alteration (1573 m to the deepest samples) includes replacement of margins of shards with palagonite and growth of pore‐filling chabazite. The porosity is reduced by cementation to less than 4% at 1573 m. Porosity does not decrease further down hole, nor does the thickness of palagonite rims on shards increase through the zone of palagonitic alteration. In these samples, palagonite is not an intermediate alteration product in the development of smectite. Rather, in hyaloclastites from the HSDP core, palagonite has formed after all observed smectites. Current downhole temperatures at the boundaries between the three alteration zones are in the range from 12° to 15°C, suggesting that geochemical thresholds or vital effects, not temperature conditions, control different outcomes of alteration.

Discrimination against 4-methyl sterol uptake during steryl chlorin ester production by copepods

To investigate possible reasons for the discrepancy between the abundance of 4-methyl components in free sterols and steryl chlorin esters (SCEs) which is commonly observed in sediments, experiments in which the copepod Calanus helgolandicus grazed on the dinoflagellates Prorocentrum micans and Alexandrium tamarense were carried out. With P. micans all the algal sterols were esterified as SCEs in the faecal pellets, but there was clear discrimination against the uptake of 4-Me sterols. This discrimination was also evident with A. tamarense. To investigate changes in the faecal pellet SCE and the free sterol distributions during pellet ageing in the P. micans experiment, portions were allowed to stand for up to 29 days in seawater in the dark. Although degradation of SCEs occurred, their esterified sterol distribution remained unchanged. The free sterols were degraded more rapidly than the SCEs and changes in the distribution were observed. This provides further laboratory evidence that sedimentary SCE sterols are more robust markers of phytoplankton communities than the corresponding free sterol distributions. Comparison of the SCE abundance in sterilised and unsterilised pellets indicated that the degradation was a result of microbial activity.

Suppressive compost for biocontrol of soilborne plant pathogens

Compost produced from agricultural wastes can be used as the organic component of container media. We have studied the properties of composted grape marc (CGM) and composted separated cattle manure (CSM). Media amended with these composts were found to be suppressive to soilborne plant pathogens such asRhizoctonia solani andPythium aphanidermatum. Suppression is the result of microbial activity developing during the composting process. It is suggested that suppressive compost can be used in horticulture as a means of biological control.

Changes in the nitrogenous components of gamma‐irradiated and inoculated ensiled ryegrass

AbstractA study was made of the role of plant and microbial enzymes in the major nitrogenous changes during ensilage. Perennial ryegrass was ensiled directly, after gamma‐irradiation, and after inoculation of the sterile grass with homofermentative lactobacilli. Plant enzymes mainly were responsible for proteolysis, whereas amino acid metabolism was the result of microbial activity. Inoculation reduced proteolysis: this was considered to be a result of rapid acidification. Lactobacillus plantarum and Streptococcus faecalis were shown to be non‐proteolytic species with a limited ability to catabolise amino acids. Substantial quantities of water‐soluble carbohydrates were made available during ensilage.

Organic Matter Inputs to Soil After Growth of Carbon‐14‐Nitrogen‐15 Labeled Maize

AbstractAfter growth of doubly labeled (14C and 15N) maize (Zea mays L.), two loamy soils were labeled by root exudation and rhizodeposition, and by direct microbial immobilization of N. Fresh roots were then carefully separated and washed, eliminating organic and organomineral cementing agents by acid and alkaline solubilizing reagents, and the remaining insoluble humin was water dispersed in order to separate coarse, medium, and fine fractions. At harvest time, fresh roots represented 85% of the total C input, and rhizodeposition 15%. Sixty to 70% of the N input was still in living roots at this time, and other organic forms of N were more a result of microbial activity than of rhizodeposition. The largest and most homogeneous organic fraction was the finest insoluble fraction, in which about half of the label for both C and N was found.

Fatty acid composition of organic detritus from Spartina alterniflora

The fatty acid composition and concentration of the marsh grass Spartina alterniflora were determined monthly (January to December, 1971) on samples of stems and leaves collected from Bissel Cove, Narragansett Bay, Rhode Island. Seasonal differences were found in both composition and concentration. The fatty acids present in suspended organic matter collected at the mouth of Bissel Cove during ebb and flood tide for the same period have also been analyzed. Laboratory model studies involving the formation of suspended organic matter by the decomposition of S. alterniflora have been investigated under aerobic and anaerobic conditions, using both organic solvent-extracted and non-extracted grass. Field model studies were also conducted on marsh grass decomposing in Bissel Cove, using both extracted and non-extracted grass. The fatty acid composition and concentration of suspended organic matter formed in the various model studies were similar to those found in the natural material and differed markedly from that of S. alterniflora. The total fatty acid concentration and the branched chain 15-carbon acids of both natural and model suspended matter gave higher values than those found in S. alterniflora. These branched chain acids appear to be the result of microbial activity and their high levels in the suspended organic matter, together with the fatty acid concentrations of the model studies using extracted marsh grass, indicate that micro-organisms are very important in the formation of the natural organic detritus.

Role of Bacteria in Decomposition of Injected Liquid Waste at Wilmington, North Carolina: ABSTRACT

In 1968, Hercules Chemical, Inc., Wilmington, North Carolina, began injecting organic waste through wells into a saline-disposal zone at depths of 850-1,000 ft. The waste, which is a by-product of dimethyl terephthalate used in the production of synthetic fiber, is composed of water, with a pH of about 4.0, containing approximately 15,000 ppm acetic acid, 5,000 ppm formic acid, and 500 ppm methanol. The movement and composition of the transformed waste have been monitored by a network of 14 observation wells drilled to various depths. The waste-water analysis and monitoring were performed by the U.S. Geological Survey. In June 1972, waste was detected in observation well 14. The microbial population was periodically sampled as the dissolved organic carbon fraction increased. The dissolved organic content increased to 112 mg/1, and then rapidly decreased to 20 mg/l. This sudden decrease in dissolved organic carbon was accompanied by the appearance of gas composed of approximately 60% methane. Each time a decrease in dissolved organic carbon occurred, gas was found and an increase in the total microbial population was measured. Methane gas production is the result of microbial activity. The injected waste contains adequate carbon and energy substrates for the strictly anaerobic, methane-producing bacteria which have been isolated from well 14. In addition to the methane-producing bacteria, other bacteria have been isolated and identified. Microorganisms such as Agrobacterium, Pseudomonas (especially species fluorescens), Proteus, Bacillus, Arthrobacter, Aerobacter, Corynebacterium, and Staphylococcus have been observed. The total microbial population was found to be 25 × 108 organisms per milliliter in well 14 and 30 × 108 organisms per milliliter in the unpolluted aquifer. The source of these bacteria is the natural aquifer, inasmuch as the injected waste is sterile. The wast alone does not support a microbial population for it contains no nitrogen. Such nitrogen substrate is apparently supplied by the natural water in the aquifer. End_of_Article - Last_Page 1594------------

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