Growth Of Most Microorganisms Research Articles

Effect of modified atmosphere packaging on the quality characteristics and bacterial community succession of super-chilled chicken meat in biopreservation

Microbial contamination and growth play an important role in the spoilage and quality loss of chicken meat. This study, therefore, aims to explore the effect of modified atmosphere packaging (MAP) on the quality characteristics and bacterial community succession of chicken meat in biopreservation under superchilling (−1 °C) conditions. In Group 3 (15% O₂/30% CO₂/55% N₂), the result revealed an enhancement in color, while reducing the total volatile basic nitrogen (TVB-N), thiobarbituric acid reactive substances (TBARS), pH, total viable count (TVC), Pseudomonas count, lactic acid bacteria (LAB) count, and Enterobacteriaceae count were found in Group 1 (30% CO₂/70% N₂) in comparison to the control (CON) during 30 d of storage. The MAP chicken meat had a more intricate bacterial succession process than the CON, mainly because MAP can prolong the lag phase of microbial growth, thus inhibiting the growth of most microorganisms. During the entire storage period, Pseudomonas was the predominant bacterial flora of CON, while it was significantly inhibited in the MAP groups, with Serratia and Delftia being the most abundant. These results indicate that Group 1 was superior to other groups in preventing bacterial development and maintaining steady quality traits of chicken meat during the 30 d of storage period.

Microbe-driven elemental cycling enables microbial adaptation to deep-sea ferromanganese nodule sediment fields

BackgroundFerromanganese nodule-bearing deep-sea sediments cover vast areas of the ocean floor, representing a distinctive habitat in the abyss. These sediments harbor unique conditions characterized by high iron concentration and low degradable nutrient levels, which pose challenges to the survival and growth of most microorganisms. While the microbial diversity in ferromanganese nodule-associated sediments has been surveyed several times, little is known about the functional capacities of the communities adapted to these unique habitats.ResultsSeven sediment samples collected adjacent to ferromanganese nodules from the Clarion–Clipperton Fracture Zone (CCFZ) in the eastern Pacific Ocean were subjected to metagenomic analysis. As a result, 179 high-quality metagenome-assembled genomes (MAGs) were reconstructed and assigned to 21 bacterial phyla and 1 archaeal phylum, with 88.8% of the MAGs remaining unclassified at the species level. The main mechanisms of resistance to heavy metals for microorganisms in sediments included oxidation (Mn), reduction (Cr and Hg), efflux (Pb), synergy of reduction and efflux (As), and synergy of oxidation and efflux (Cu). Iron, which had the highest content among all metallic elements, may occur mainly as Fe(III) that potentially functioned as an electron acceptor. We found that microorganisms with a diverse array of CAZymes did not exhibit higher community abundance. Instead, microorganisms mainly obtained energy from oxidation of metal (e.g., Mn(II)) and sulfur compounds using oxygen or nitrate as an electron acceptor. Chemolithoautotrophic organisms (Thaumarchaeota and Nitrospirota phyla) were found to be potential manganese oxidizers. The functional profile analysis of the dominant microorganisms further indicated that utilization of inorganic nutrients by redox reactions (rather than organic nutrient metabolism) is a major adaptive strategy used by microorganisms to support their survival in the ferromanganese nodule sediments.ConclusionsThis study provides a comprehensive metagenomic analysis of microbes inhabiting metal-rich ferromanganese nodule sediments. Our results reveal extensive redundancy across taxa for pathways of metal resistance and transformation, the highly diverse mechanisms used by microbes to obtain nutrition, and their participation in various element cycles in these unique environments.7UX-FAbsHcrvGN6PxGni8JVideo

Aerobic composting of chicken manure with amoxicillin: Alpha diversity is closely related to lipid metabolism, and two-component systems mediating their relationship

Composting is a technology that can use various functional microorganisms to degrade antibiotics. However, antibiotics will cause a coercion for the growth of most microorganisms. Microorganism can survive different environments, thanks to the development of different adaptive responses. Often, two-component systems sense changes in the environment and trigger a cellular response and adaptation. Therefore, the main purpose of this study was to explore how the two-component system modulates the corresponding metabolic functions to affect alpha diversity during composting. The results show that amoxicillin increases species diversity, reduces species richness. Lipid metabolism is an important metabolic pathway mediating changes in alpha diversity. Two-component system indirectly affects alpha diversity by regulating lipid metabolism. Firmicutes are important microbial communities mediating changes in alpha diversity This work presents an understanding of the impact of environmental information processing on microbial diversity, during composting.

Physicochemical properties, antioxidant and antimicrobial activities of Nigerian Polyfloral honeys

Natural honey is widely applied as food sweetener, food preservative and in folk medicine for treatment of varying degree of human affliction and diseases. This study evaluates the antimicrobial activities, physicochemical, phytochemical and antioxidant properties of four Nigerian honey samples collected from Ekiti, Kogi, Osun and Ondo (coded as A, B, C and D respectively). Physicochemical determination of honey samples include: pH, free acidity, electrical conductivity and density. Determination of phytochemical was carried out quantitatively using phenolics and flavonoid; while the total antioxidant capacities was measured in an in-vitro system using inhibition of lipid peroxidation, thiobarbituric acid reactions and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity. Agar diffusion method was used to measure the antimicrobial activities of the honey samples against some selected microorganisms (Staphylococcus aureus, Bacillus subtilis, Psuedomonas aeruginosa and Escherichia coli). The results of the physicochemical characterization showed that the honey samples were polyflorals characterized by low pH (3.76 ± 0.02, 4.17 ± 0.15, 3.94 ± 0.10 and 3.77 ± 0.01 for A, B, C and D respectively) capable of inhibiting the growth of most microorganisms and density ranging between 1.38 and 1.45 g/ml. All the honey samples showed antimicrobial activity against the selected microorganisms at concentration greater than 60 % v/v. The antioxidant investigation also demonstrated ability to inhibit lipid peroxidation and thiobarbituric acid reactions and 2, 2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity possibly due to the reasonable amount of flavonoids and phenolics therein.

Metabolic Detoxification of 2-Oxobutyrate by Remodeling Escherichia coli Acetate Bypass.

2-Oxobutyrate (2-OBA), as a toxic metabolic intermediate, generally arrests the cell growth of most microorganisms and blocks the biosynthesis of target metabolites. In this study, we demonstrated that using the acetate bypass to replace the pyruvate dehydrogenase complex (PDHc) in Escherichia coli could recharge the intracellular acetyl-CoA pool to alleviate the metabolic toxicity of 2-OBA. Furthermore, based on the crystal structure of pyruvate oxidase (PoxB), two candidate residues in the substrate-binding pocket of PoxB were predicted by computational simulation. Site-directed saturation mutagenesis was performed to attenuate 2-OBA-binding affinity, and one of the variants, PoxBF112W, exhibited a 20-fold activity ratio of pyruvate/2-OBA in substrate selectivity. PoxBF112W was employed to remodel the acetate bypass in E. coli, resulting in l-threonine (a precursor of 2-OBA) biosynthesis with minimal inhibition from 2-OBA. After metabolic detoxification of 2-OBA, the supplies of intracellular acetyl-CoA and NADPH (nicotinamide adenine dinucleotide phosphate) used for l-threonine biosynthesis were restored. Therefore, 2-OBA is the substitute for pyruvate to engage in enzymatic reactions and disturbs pyruvate metabolism. Our study makes a straightforward explanation of the 2-OBA toxicity mechanism and gives an effective approach for its metabolic detoxification.

The effect of oregano ( Origanum vulgare ) essential oil on four Salmonella serovars and shelf life of refrigerated pork meat packaged under vacuum and modified atmosphere

The survival of Salmonella Enteritidis, S. Typhimurium, S. Infantis, and S. Montevideo in experimentally inoculated (10⁶ CFU/g) minced pork meat containing different concentrations (0%, 0.3%, 0.6%, or 0.9%) of oregano (Origanum vulgare) essential oil (OEO) packaged under vacuum or MAP (30%O₂/50%CO₂/20%N₂) were evaluated within 15 days of refrigeration (3 ± 1°C) storage. Carvacrol was the predominant constituent in OEO (77.16%). The minimum inhibitory concentration of OEO was similar for all Salmonella serovars (160–320 μg/ml). Salmonella counts in minced pork were reduced by 2.09 and 3.08 log CFU/g in the samples treated with 0.3% and 0.6% OEO, respectively. Addition of 0.9% OEO reduced the Salmonella count to below the limit of detection. Experiments also included investigation of OEO effect on Enterobacteriaceae, LAB and TVC. For both packaging methods the use of OEO increased the microbial shelf life of pork. Sensory analyses showed that the samples with 0.3% OEO added were the most acceptable. PRACTICAL APPLICATIONS: Due to its nutritional characteristics, minced meat is suitable for the growth of most microorganisms including spoilage bacteria and foodborne pathogens such as Salmonella spp. The microbial safety of minced meat is very important. Taking into account that these bacteria are one of the most important from the aspect of meat safety, their control, especially in minimally processed meat products, is crucial. OEO not only exhibited strong anti‐Salmonella effects, but, in contrast to some other essential oils, is categorized as “GRAS” (generally recognized as safe) and can be considered as a natural preservative used in organic production as an alternative to synthetic additives. Our findings could also guide the selection of an effective concentration of OEO that is organoleptically acceptable.

Conversions of Benzoxazinoids and Downstream Metabolites by Soil Microorganisms

Benzoxazinoids, secondary metabolites of several Poaceae, and some benzoxazinoid downstream metabolites are bioactive compounds that act as allelochemicals and natural pesticides. Since a short lifetime of the substances is crucial to avoid long-term environmental effects, total degradation by microorganisms is of exceptional importance. We performed a screening with cultivable microorganisms (Species names and strain numbers: Mycobacterium fortuitum, 7; Bacillus aryabhattai, 34; Bacillus cereus, 59; Bacillus megaterium, 21, 48; Bacillus methylotrophicus, 58; Lysinibacillus xylanilyticus, 56; Paenibacillus polymyxa, 51; Aminobacter aminovorans, 49; the fungi Papulaspora sepedonioides, 12 and Trichoderma viride, 47) isolated from soil previously used for wheat and Persian clover mixed-culture systems to assess their behavior in the presence of the compounds. The microorganisms were exposed to glucosylated benzoxazinones, the benzoxazinones HBOA, DIBOA and DIMBOA, the benzoxazolinones BOA, BOA-6-OH, and MBOA, and to several downstream products (AP, AAP, oHPMA, glucoside carbamate) in liquid culture to avoid interferences with soil minerals and other organisms. The microorganisms differed strongly in their metabolic activities in terms of growth, compound modification, and degradation. We observed degradation with DIBOA and GDIMBOA but rarely with DIMBOA, whereas BOA and MBOA showed almost no degradation when directly applied. Hydroxylation of BOA and demethylation of MBOA by the plant, resulting in BOA-6-OH, activated the benzoxazolinones for bacterial nitration. The resulting NBOA-6-OH was short-lived but could function temporarily as an allelochemical by inhibiting photosynthesis, e.g., in young seedlings of cress and kohlrabi. The BOA downstream products AP and oHPMA were converted to AAP, which can be nitrated to N-(2-OH-5-nitrophenyl)-acetamide and then degraded by A. aminovorans (49) and P. polymyxa (51). Only P. sepedonioides (12) and P. polymyxa (51) failed in the conversion of HBOA into AAP. While DIBOA, DIMBOA, MBOA, NBOA-6-OH, AP, AAP, and oHPMA reduced the growth of most microorganisms, glucoside carbamate promoted their growth. GDIMBOA had a stimulatory effect towards the fungi and three bacterial species. These findings lead to the hypothesis that in a natural habitat, such as the root surface, microorganisms may cooperate, perhaps by involving the plant, for the successful elimination of benzoxazinoids and their downstream metabolites.

Phenotypic Characterization of some Actinobacteria and Fungi Isolated From Exposed rock surfaces in Southwestern Sinai, Egypt

The search of novel strains continues to be of great importance in research around the world for pharmaceutical, industrial, agricultural and biomining applications. The present study aims to investigating the microbial diversity of rock samples collected from Um Bogma formation, southwestern Sinai, Egypt which was chosen for its unique location, geological and physicochemical properties. The studied samples showed small microbial diversity and low microbial count. A total of ten isolates of actinobacteria and ten isolates of fungi were isolated and characterized phenotypically. The results indicated that all the isolated actinobacteria belong to the genus Streptomyces. They were all halotolerant with some showing antimicrobial activities when tested against Bacillus subtilis, Pseudomonas aeruginosa ATCC 9027, Staphylococcus aureus ATCC 6538, Escherichia coli ATCC 8739, Candida albicans and Aspergillus flavus. On the other hand, all the studied fungal isolates belong to the genus Aspergillus. They showed resistance to the antifungal nystatin when a concentration of 50 µg per ml was used. The studied locations is characterized by their harsh conditions which does not support the growth of most microorganisms which includes a temperature ranging from below 0°C at night to above 46°C throughout the day, low water content and organic matter hosting radioactive and heavy elements. Rock-dwelling microbial communities that survived such conditions open further research investigations on studying phylogenetic relationships between them as well as their possible microbial activities that can be of environmental and industrial importance.

Prevalence of spoilage microorganism, Pseudomonas spp. on restaurants cutting boards collected in Seri Kembangan, Malaysia.

Due to the tropical climate that promotes the growth of most microorganisms, the food service industry in Malaysia faces a lot of challenges in order to ensure quality foods are served to the customers. One of the bacteria that are associated with food spoilage is Pseudomonas spp., and the presence of these bacteria on cutting boards could cross-contaminate food items during food handling. This study performed pyrosequencing analysis to investigate the existence of microbial communities on cutting boards collected from restaurants in Seri Kembangan, Malaysia. Most of the samples were dominated by Flavobacteriales, Enterobacteriales, Lactobacillales, and Pseudomonadales. This study discovered that, all samples of cutting boards were contaminated with Pseudomonas spp. With the mean bacterial count of 1.4 × 106 cfu/cm2, 5.1 × 105 cfu/cm2 and 5.6 × 106 cfu/cm2 on samples collected from clean, moderately clean and less clean food premises, respectively. The study shows that the contamination level of Pseudomonas spp. was not significantly different in different grades of food premises. Regardless of the status and grades of the food premises, they have the same likelihood to introduce spoilage bacteria like Pseudomonas spp. from cutting board to food if they neglect correct food handling measures. Therefore, all food handlers need to prioritize safe food handling to avoid food contamination and spoilage.

Microbial Diversity and Putative Opportunistic Pathogens in Dishwasher Biofilm Communities.

ABSTRACTExtreme habitats are not only limited to natural environments, but also exist in manmade systems, for instance, household appliances such as dishwashers. Limiting factors, such as high temperatures, high and low pHs, high NaCl concentrations, presence of detergents, and shear force from water during washing cycles, define microbial survival in this extreme system. Fungal and bacterial diversity in biofilms isolated from rubber seals of 24 different household dishwashers was investigated using next-generation sequencing. Bacterial genera such as Pseudomonas, Escherichia, and Acinetobacter, known to include opportunistic pathogens, were represented in most samples. The most frequently encountered fungal genera in these samples belonged to Candida, Cryptococcus, and Rhodotorula, also known to include opportunistic pathogenic representatives. This study showed how specific conditions of the dishwashers impact the abundance of microbial groups and investigated the interkingdom and intrakingdom interactions that shape these biofilms. The age, usage frequency, and hardness of incoming tap water of dishwashers had significant impact on bacterial and fungal community compositions. Representatives of Candida spp. were found at the highest prevalence (100%) in all dishwashers and are assumed to be one of the first colonizers in recently purchased dishwashers. Pairwise correlations in tested microbiomes showed that certain bacterial groups cooccur, as did the fungal groups. In mixed bacterial-fungal biofilms, early adhesion, contact, and interactions were vital in the process of biofilm formation, where mixed complexes of bacteria and fungi could provide a preliminary biogenic structure for the establishment of these biofilms.IMPORTANCE Worldwide demand for household appliances, such as dishwashers and washing machines, is increasing, as is the number of immunocompromised individuals. The harsh conditions in household dishwashers should prevent the growth of most microorganisms. However, our research shows that persisting polyextremotolerant groups of microorganisms in household appliances are well established under these unfavorable conditions and supported by the biofilm mode of growth. The significance of our research is in identifying the microbial composition of biofilms formed on dishwasher rubber seals, how diverse abiotic conditions affect microbiota, and which key microbial members were represented in early colonization and contamination of dishwashers, as these appliances can present a source of domestic cross-contamination that leads to broader medical impacts.

Modelling the effect of pH and water activity in the growth of Aspergillus fumigatus isolated from corn silage.

The aim of this work was to use mathematical kinetic modelling to assess the combined effects of aW, pH, O2 availability and temperature on the growth rate and time to growth of Aspergillus fumigatus strains isolated from corn silage. A full factorial design was used in which two factors were assayed: pH and aW . The aW levels assayed were 0·80, 0·85, 0·90, 0·92, 0·94, 0·96, 0·98 and 0·99. The levels of pH assayed were 3·5, 4, 4·5, 5, 6, 7, 7·5 and 8. The assay was performed at normal oxygen tension at 25 and 37°C, and at reduced oxygen tension at 25°C. Two strains of A. fumigatus isolated from corn silage were used. Kinetic models were built to predict growth of the strain under the assayed conditions. The cardinal models gave a good quality fit for radial growth rate data. The results indicate that the environmental conditions which take place during silage production, while limiting the growth of most micro-organisms, would not be able to control A. fumigatus. Moreover, pH levels in silage, far from limiting its growth, are also close to its optimum. Carbon dioxide at 5% in the environment did not significantly affect its growth. A need for a further and controlled acidification of the silage exists, as no growth of A. fumigatus was observed at pH 3·5, as long as the organoleptic characteristics of the silage are not much compromised. Aspergillus fumigatus is one of the major opportunistic pathogens able to cause illness such as allergic bronchopulmonary aspergillosis, aspergilloma and invasive aspergillosis to rural workers. Exposure of animals to A. fumigatus spores can result in infections, particularly in those organs exposed to external invasion, such as the airways, mammary gland and uterus at birth.

Amylolytic Yeasts: Producers of α-amylase and Pullulanase

Amylases are among the most important enzymes used in various industries. They represent approximately 30% of the world enzyme production. These are of ubiquitous occurrence and hold the maximum market share of enzyme sales. These comprise hydrolases, which hydrolyze starch to diverse products as dextrins, and progressively smaller polymers composed of glucose units. They are highly demanded in various arrays such as food, pharmaceuticals, textiles, detergents, etc. However, enzymes from mold and bacterial source have dominated applications in industrial sectors while few species of yeast were studied for the amylases production. This review focuses on the amylolytic yeasts and their enzymes and we were interested at αamylase and pullulanase, their distribution, structural-functional aspects, physical and chemical parameters, and the use of these enzymes in industrial applications. Key-wordsAmylolytic yeast, α-amylase, Pullulanase, Industrial application -------------------------------------------------IJLSSR----------------------------------------------INTRODUCTION Different amylases catalyze the enzymatic hydrolysis of starch as α -amylases (EC3.2.1.1), glucoamylases (EC 3.2.1.3), β-amylases (EC 3.2.1.2.) and debranching enzymes such as pullulanases (EC 3.2.1.41). However, with the advances in biotechnology, the amylase application has expanded in many fields such as clinical, medicinal and analytical chemistry, as well as their widespread application in starch saccharification and in the textile, food, detergent, brewing and distilling industries [1-2]. Although they can be derived from several sources, such as plants, animals and microorganisms, fungi and bacteria have been extensively screened for amylases production [1]. Recently, some amylases from yeasts have been found to have the ability to hydrolyze starch: α-amylase and glucoamylase from Schwanniomyces castelli [3], glucoamylases from S. fibuligera [4] and Candida antarctica [5], α-amylase from Cryptococcus sp. S-2 [6], Access this article online Quick Response Code: Website: www.ijlssr.com DOI: 10.21276/ijlssr.2016.2.4.6 Candida lusitaniae, Candida famata [7], amylopullulanase from Clavispora lusitaniae ABS7 [8] and pullulanase from Aureobasidium pullulans [9]. A number of reviews exist on bacterial and fungal amylases and their applications, however, none specifically covers yeast amylases. α-amylases and pullulanase are one of the most popular and important form of industrial amylases and the present review highlights the various aspects of these yeast amylases. Industrial use yeasts or their enzymes Yeasts are used by humans for thousands of years with wide application, both fundamental and industrial, in science, food, medical and agricultural. Yeasts are traditionally involved in many food fermentations and manufacturing products such as beers, ciders, wines, sake, baked goods, cheese, sausages and other fermented foods. Industrial processes involve long since yeast in the production of fuel ethanol from single cell protein (SCP) for animal feed or industrial enzymes, vaccine production and carotenoids [10-11] (Table 1). The yeast extract is an important nutrient (nitrogen source and intake of essential vitamins group B), particularly favorable to the growth of most microorganisms. Yeasts are also involved in the development of agricultural and industrial waste for the production of proteins, enzymes and SPC [12]. The enzymes of yeast are increasingly Review Article (Open access) Int. J. Life. Sci. Scienti. Res., VOL 2, ISSUE 4 http://ijlssr.com IJLSSR © 2015 All rights are reserved Page 340 used in industries to facilitate the process and reduce the energy cost of the finished product particularly in the food industry. The search for new yeast enzymes having an industrial application potential continues to grow. Yeasts such as Pichia pastoris, Saccharomyces cerevisiae and Hansenula polymorpha are currently used for the industrial production of proteins and enzymes, including pharmaceutical proteins [13]. The yeast Yarwinia lipolytica and Rhodotorula glutinis are used due to their ability to produce lipase in petroleum industries, laundry, detergent industry and the IAA [14]. Table 1: Industrial Enzymes produced by yeasts [13,15-16] Enzyme Yeasts Industry Chymosine Klyveromyces sp. Food processing Saccharomyces cerevisiae Galactosidase Saccharomyces sp. Food applications Glutaminase Zygosaccharomyces rouxii Therapeutic analysis Inulinases Candida sp. Food applications Klyveromyces marxianus Invertase Saccharomyces cerevisiae Food applications Lactase Candida pseudotropicalis Food processing

Study on Influence Factors in Bacillus Thuringiensis Production by Semi-solid State Fermentation Using Food Waste

Bacillus thuringiensis(Bt) bio-pesticides is a kind of selective and efficient pesticides, but the high cost of raw materials always limits its development, food waste contains superior nutritional elements which could sustain the growth of most microorganisms. So we choose food waste as the material, explored its feasibility of producing bio-pesticides and optimized the influence parameters during the fermentation process. In this work, food waste with 75% water content presented δ-endotoxin efficiency of 862μg/mL, spore count of 2.23×1011 CFU/mL and entomotoxicity of 56560 IU/mg. The influence factors during fermentation process were optimized by asingle-factor indextest, and the result showed that initial pHhad a max effect on the fermentation performance. The optimum fermentation conditions were0.2% inoculum size, 2% salt content, 5% or less oil content, and the initial pH adjusted to 7.0, inoptimized conditions, the δ-endotoxin outputwas2310μg/mL and the entomotoxicity was 56875IU/mgafter fermentation. It seemed to be a promising way to make use of food waste.

Antimicrobial Potential of Lycosin-I, a Cationic and Amphiphilic Peptide from the Venom of the Spider Lycosa singorensis

Antimicrobial peptides (AMPs) are significant components of the innate immune system and play indispensable roles in the resistance to bacterial infection. Here, we investigated the antimicrobial activity of lycosin-I, a 24-residue cationic anticancer peptide derived from Lycosa singorensis with high structural similarity to several cationic and amphiphilic antimicrobial peptides. The antimicrobial activity of lycosin-I against 27 strains of microbes including bacteria and fungi was examined and compared with that of the Xenopus-derived AMP magainin 2 using a microdilution assay. Lycosin-I inhibited the growth of most microorganisms at low micromolar concentrations, and was a more potent inhibitor than magainin 2. Lycosin-I showed rapid, selective and broad-spectrum bactericidal activity and a synergistic effect with traditional antibiotics. In vivo, it showed potent bactericidal activity in a mouse thigh infection model. High Mg2+ concentrations reduced the antibacterial effect of lycosin-I, implying that the peptide might directly interact with the bacterial cell membrane. Uptake of the fluorogenic dye SYTOX and changes in the surface of lycosin-Itreated bacterial cells observed by scanning electron microscopy confirmed that lycosin-I permeabilized the cell membrane, resulting in the rapid bactericidal effect. Taken together, our findings indicate that lycosin-I is a promising peptide with the potential for the development of novel antibacterial agents.

The Storage of Dried Apricots: The Effect of Packaging and Temperature on the Changes of Texture and Moisture

During storage, the packaging material was crucial in the product's moisture variation. The aim of this work was to study the changes of both the moisture content and the texture of dried apricots packaged in two types of containers, namely glass and polypropylene trays, which were thermosealed with two different films and stored at a constant temperature (5, 15, 25 and 35C). The moisture content and texture of the product were analyzed periodically over a period of 12 months. In addition, a differential scanning calorimetry of the product was carried out for a better understanding of the relationship between these parameters. In samples packaged in films, the maximum force value increased along with storage temperature, while the moisture content decreased. In glass, the values of these parameters remained almost constant. A change in the structure of the material was detected between 25 and 35C. Practical Applications The texture of the food is one of the most important characteristics as far as consumer acceptance is concerned. The moisture content has a determining influence on the changes of food properties, such as texture, color and nutritional value. In addition, below a certain level of moisture, the growth of most microorganisms is inhibited. The shelf life of foods depends on the storage conditions, which could have an effect on food characteristics like phase transitions. In the event of a phase transition, the transition temperature should not be exceeded during storage and distribution, because changes are triggered. This work studies the changes of both the moisture content and the texture of dried apricots stored under different conditions and it also includes a calorimetric analysis of the dried product, in order to detect phase transition in the range of storage temperatures.

<i>In Vitro</i> Studies of Antibacterial Activity of Bioglasses Releasing Ag<sup>+</sup>

The research of obtained bioglasses in the form of silver-containing powders were presented in this paper. The research conducted in order to determine antimicrobial activity under in vitro conditions of bioglasses. The results confirmed that these bioglasses Z-5, Z-8 and B-I inhibit the growth of most micro-organisms during the tested period and could be used in surgical treatment of the most advanced parodontium illnesses.

Modeling of the process of moisture loss during the storage of dried apricots

Moisture content is a reference parameter for dried food because the growth of most microorganisms is inhibited below certain water activity levels. In addition, it has a determining influence on the evolution of important parameters, such as color and flavor, and on other properties and deterioration reactions, such as texture, oxidation processes and nutritional value. During the storage of some dried fruits, moisture is produced due to Maillard reactions and exchanged with the surrounding environment through the packaging. The evolution of dried foods during their shelf life depends on the storage conditions. The aim of this study is to analyze the evolution of the moisture content in dried apricots packaged in different types of containers, namely glass and thermosealed polypropylene trays. The samples were stored at constant temperatures: 5, 15, 25 and 35 °C and were analyzed periodically over a period of 12 months. The sorption isotherms of apricots used in this study were also determined. In order to model how the moisture evolved, an empirical kinetic model was tested. This model considers both water transfer from the fruit and also water production as a result of the Maillard processes. The explained variance was higher than 95% in the samples stored in trays, which were thermosealed with film.

Microbiological and biochemical survey on the transition of fermentative processes in Fukuyama pot vinegar brewing

Traditional brewing of Fukuyama pot vinegar is a process that has been continued in Fukuyama, Kagoshima, Japan, for almost 200 years. The entire process proceeds from raw materials, including steamed rice, rice koji (steamed rice grown with a fungus, Aspergillus oryzae) and water, to produce vinegar in roughly capped large pots laid in the open air. No special fermentative manipulation is required, except for scattering dried rice koji (called furi-koji) on the surface of the mash to form a cap-like mat on the surface at the start of brewing. As the biochemical mechanism of the natural transition of the fermentative processes during brewing has not been fully explained, we conducted a microbiological and biochemical study on the transition. First, a distinct biochemical change was observed in the brewing of spring preparation; that is, a sharp decline in pH from 6.5 to 3.5 within the first 5 days of brewing was observed due to lactic acid fermentation. Alcoholic fermentation also proceeded with a sharp increase to 4.5% ethanol within the first 5 days under the acidic conditions, suggesting that saccharification and both fermentations proceed in parallel. Acidic conditions and ethanol accumulation restricted the growth of most microorganisms in the mash, and in turn provided a favorable growth condition for acetic acid bacteria which are acid resistant and "ethanol-philic." Acetic acid was detected from day 16 and gradually increased in concentration, reaching a maximum of 7% at day 70 that was maintained thereafter. Empirically furi-koji naturally sinks into the mash after around day 40 by an unknown mechanism, allowing acetic acid bacteria to easily form pellicles on the mash surface and promoting efficient acetic acid fermentation. Dominant microbial species involved in the three fermentations were identified by denaturing gradient gel electrophoresis analysis using PCR-amplified defined-regions of small rDNA from microorganisms in the brewing mash or colony direct PCR applied to isolated microorganisms from the mash.

Degradation of phenol in seawater using a novel microorganism isolated from the intestine of Aplysia kurodai

Phenol is an organic compound widely used as a solvent. It is discharged by various industries into rivers and then accumulates in lakes and seawater. It is difficult to treat phenol in seawater by biological means because the high concentrations of dissolved mineral salts in seawater inhibit the growth of most microorganisms. We investigated the bioremediation of phenol in seawater using a novel microorganism isolated from the intestine of a marine slug. A novel bacterium was isolated from the intestine of the sea slug (Aplysia kurodai) using enrichment culture with a high concentration of phenol. From experimental research on the bacterium's morphological, and chemotaxonomic characteristics, and using molecular (16S rDNA) techniques, it was found that it belongs to the genus Serratia. Serratia sp. could degrade phenol completely; this is in contrast to activated sludge, which degraded only about 35% of phenol in seawater. This novel microorganism seems to have the potential for the efficient treatment of organic pollutants in seawater.

Effects of Metsulfuron-Methyl on the Microbial Population and Enzyme Activities in Wheat Rhizosphere Soil

The effects of metsulfuron-methyl, a sulfonylurea herbicide, on the wheat soil microorganisms were evaluated by the methods of microbial inoculation culture, and the activities of three enzymes were measured using the colorimetric method. The tolerant microorganisms that can resist 500 μ g·g−1 metsulfuron-methyl in the counting culture medium were studied specially. Metsulfuron-methyl distinctly inhibited the common aerobic heterotriphic bacteria, but the effects on common fungi and common actinomycete were not evident. In the meantime, the number of tolerant fungi increased greatly in the rhizosphere after the application of metsulfuron-methyl in contrast to the significant decrease of the amount of tolerant actinomycete. It indicates that fungi might turn into the dominant microbial type and actinomycete is the sensitive factor in the soil polluted by sulfonylurea residues. The population of aromatic compounds–decomposing bacteria, aerobic azotobacter, and nitrite bacteria all increased in the earlier period, but the aerobic azotobacter decreased rapidly in number 30 days later, and the amount of nitrite bacteria also showed a temporary decrease with time 15 days later. However, the denitrifying bacteria just began to increase significantly after the crops had grown for 50 days. The amount of sulfur-oxidizing bacteria gradually decreased with the growth of crops, and so were the sulfate-reducing bacteria after metsulfuron-methyl application. To all types of microorganisms, there were more microbes in rhizosphere samples than those in nonrhizosphere except aerobic azotobacter. It means the growth of wheat root system can stimulate the growth of most microorganisms. The activities of hydrogen peroxidase and polyphenol oxidase in soil samples after metsulfuron-methyl application were notably lower than those in the control, and the difference of the activities between the samples of rhizosphere and nonrhizosphere was evident. On the contrary, the activity of dehydrogenase was not inhibited by the application of metsulfuron-methyl, and the rhizosphere effect was not obvious either.