The amounts of cadmium in soil solution are a resultant of its mobilization from the soil solid phase and its immobilization from the soil solution. Microbial soil activity markedly affects both of these processes. Microorganisms influence cadmium mobilization throughout the modification of environmental conditions. This includes production of CO2, organic and inorganic acids, formation of soluble complexes of metal with chelates, which can be microbial metabolites or products of microbial transformation of the soil organic matter. Microbially mediated immobilization of cadmium from the soil solution can involve binding of metal by cell envelopes, its intracellular accumulation, formation of insoluble Cd complexes with extracellular biopolimers, or precipitation of cation with microbially produced inorganic anions, such as sulphides and phosphates

Soil microorganisms are important for plant growth and beneficial for the nutrition and the development of a variety of soil animals. Together with soil invertebrates they also improve nutrients availability in soils. Although not frequent in Europe , magnesite emissions can affect the nutritional status of the vegetation and the survival of soil microorganisms as well as other biota locally, and thus may be crucially responsible for the quality of the entire biotic system. The observed gradients of soil microbial characteristics reflect the physico-chemical properties of soils around the magnesite plant and may be used to predict transitory changes during amelioration

The study focuses on quantitatively important fractions of very stable organic matter in sandy arable soils in which clay and silt, commonly assumed to be the major factors for organic carbon (OC) stabilization, are practically missing. We characterized 23 Ap horizons plus one subsoil with respect to total OC, total N, chemical resistance of OC, microbial biomass, respiration in laboratory incubation and solubility of OC in water (WSOC). The soils varied with respect to historical land-use (heathland, plaggen-manuring, woodland) and soil genetic factors (podzolization, groundwater). Data from long-term experiments on sand and sandy loam were also considered. The soils revealed a wide range of OC content from below 10 to about 50 mg g(-1). C to N ratios varied between 10 and 30 and were positively linked to total OC (R2 = 0.87). Graphitized C ('charcoal', as H2O2-resistant fraction) was of minor importance, with just about 0.5 mg C g(-1) soil in most samples. Only some plaggen and heath soils had charcoal C contents around 1 and 1.5 mg g(-1) but this was still less than 5% of the total OC. The HCl-resistant C fraction, on the other hand, was extremely large, amounting to 50-90% of the total OC. Its percentage was closely related to total OC (R2 = 0.84). Biomass C contents (fumigation-extraction) were not correlated with total OC. The C-rich soils had low biomass C to total OC ratios (< 0.005). The activities of the enzymes catalase and dehydrogenase showed similar relationships. This strongly indicated that major proportions of the organic material do not support a microbial population and are not in a process of net-decomposition. The average respiration rates per unit of OC after 100 days of incubation at 20 degrees C were lowest in the C-rich samples. Water soluble organic carbon (WSOC) increased slightly with total OC. On an average, a sum of 379 +/- 80 microgram C g(-1) soil was obtained over seven sequential extractions. This was about the same amount as respired in 140 days (373 +/- 107 microgram CO2-C g(-1)) but there was no significant correlation between the respired CO2-C and the extracted WSOC. The steady-state rate of WSOC released (steps 3-7) per unit of total OC was lowest in the C-rich soils, again indicating the high stability of OC. We concluded that old sandy Ap horizons soils may have high levels of OC with high proportions of very stable (refractory) constituents amounting to more than 50% of total OC or 10-30 mg C g(-1) soil.

Due to the importance of N in forest productivity ecosystem and nutrient cycling research often includes measurement of soil N transformation rates as indices of potential availability and ecosystem losses of N. We examined the feasibility of using soil temperature and moisture content to predict soil N mineralization rates (Nmin) at the Coweeta Hydrologic Laboratory in the southern Appalachians. We conducted seasonal laboratory incubations of A and AB horizon soils from three sites with mixed-oak vegetation using temperature and moisture levels characteristic of the season in which the soils were collected. The incubations showed that temperature and temperature-moisture interactions significantly affected net soil Nmin. We used the laboratory data to generate equations relating net Nmin to soil temperature and moisture data. Using field-collected temperature and moisture data we then calculated Nmin on similar forest sites and compared predicted rates with in situ, closed-core Nmin measurements. The comparison showed that the in situ Nmin was greater than rates predicted from laboratory generated equations (slope =3.22; r2=0.89). Our study suggests that while climatic factors have a significant effect on soil Nmin, other factors also influence rates measured in the laboratory and in situ.

Predictive microbiology generally focuses on the potential outgrowth of spoilage bacteria and foodborne pathogens in foods. Little attention has been paid to the biokinetics of beneficial foodgrade microorganisms, such as lactic acid bacteria. The latter is commonly used in the food fermentation industry, mainly for the in situ production of the antimicrobial lactic acid to extend the shelf life of the food. Furthermore, many strains show additional industrial potential as novel starter cultures since they produce functional metabolites, such as bacteriocins and exopolysaccharides. The production of these functional metabolites has been demonstrated during in vitro experiments, but in many cases these novel starter cultures seem to be less efficient when applied in a food system. A modelling approach may contribute to a better understanding of the tight relation between the food environment and bacterial functionality. Primary modelling can be applied to fit the experimental data concerning cell growth, sugar metabolism, and the production of functional metabolites for a given set of environmental conditions. This led to conclusions concerning the growth-associated production of bacteriocin and exopolysaccharides, the inactivation of these molecules when cell growth levels off, and a minimum cell concentration to trigger on bacteriocin production. Examples deal with the production of the bacteriocin sakacin K by the natural fermented sausage isolate Lactobacillus sakei CTC 494, and the production of heteropolysaccharides by the yoghurt starter culture Streptococcus thermophilus LY03. Secondary modelling of biokinetic parameters quantifies the production of bacteriocin and exopolysaccharides in function of environmental factors. As an example, the specific bacteriocin production by Lb. sakei CTC 494 decreases with increasing sodium chloride concentrations. Furthermore, since the assessment of functionality is frequently hampered by the nature of the food system, mathematical modelling techniques may help to predict the functional behaviour of novel lactic acid bacteria starter cultures in a food matrix, and hence quantify in situ production. For example, a model may simulate cell growth and exopolysaccharide production of S. thermophilus LY03 in a milk environment, where direct measurements are difficult to perform.

The hygienic maintenance of food has become an increasingly important issue in recent years. This is true in the tea industry as well. In the present study, we investigated the amount of microorganisms in incoming lots of crude tea (green tea). Crude tea contains large amounts of microorganisms in comparison with oolong tea and black tea, ranging most frequently from 3 * 10E3 CFU /g to 1 * 10E4 CFU/ g. In oolong and black teas, the amount of microorganisms most frequently ranges below 3 * 10E2 CFU /g. Differences attributable to the crop year, harvesting season and a location of the plants have been neglected. We have found, however, a difference in the amount of microorganisms with two types of steaming machine: a net drum type and a conveyor type. The amount of microorganisms in crude tea from the conveyor type tends to be greater than that from the net drum type. We also investigated the quantity of microorganisms in the samples from each process stage of the plant. At the stage of fresh leaves, the amount of microorganisms in the tea sample was about 1 * 10E6 CFU/g. In tea processed in net drum type steaming machines, that was decreased to the range of 10E2-10E3 CFU/g. In tea processed in conveyor steamers, however, the amount was decreased to only 10E5 CFU/g. In late stage tea plants, the amount of microorganisms in the sample was increased, and the final amount of microorganisms in the crude tea was in the range of 10E2-10E4 CFU/g. It is presumed that two main causes on the large amounts of microorganisms in crude tea are the survival of these microorganisms in the steaming stage and the secondary contamination from late stage of plants.

The common practice in many countries of using chicken manure in soil as a source of nutrients to plants is of paramount importance in sustainable agriculture. However, the application of non-composted manure on soil could contribute to contamination of the environment by fecal microorganisms. This creates a health hazard to humans, domestic animals, and to wildlife. The impact of soil solarization on reduction of microorganism-indicators of fecal contamination in chicken manure-treated soils has not been evaluated. In this study, 1.5 kg/m2 of chicken manure was applied to 40 cm deeply-ploughed clayish calcareous soils of four greenhouses. The soils of four other greenhouses were left as control-untreated with manure. Litter incorporation in the soil was performed by a harrow with 20 cm penetration depth. Irrigation was applied to soil of the eight greenhouses to obtain an average humidity at 40 cm-soil depth equivalent to 92.9%. Soil solarization of the chicken manure-treated soils with a 50 micrometer thick-polyethylene film for a period of six weeks resulted in an average 20 cm-soil depth temperature at 15 hr of 40 degrees C in comparison to 28.3 degrees C obtained in soil with no polyethylene film application. Solarization resulted in reduction in different microorganism-indicators per gram of chicken manure-treated soil collected at 20 cm depth in comparison to the count in the same soil before solarization. The percent reduction in counts in increasing order was: Staphylococcus aureus (26.3), total bacteria (45.5), fungi (71.3), Clostridium perfringes (81.8), fecal coliform (92.6), and non-lactose fermenting bacteria (100.0).

The presence of viable microorganisms on a surface presents a ‘biotransfer potential’. These microorganisms may be actively multiplying and colonizing the surface, or may be merely surviving, retaining viability but being unable to multiply due to adverse environmental conditions. Attached microorganisms may be retained in surface features, mixed with organic material (food debris/soil) or detergent debris. Microorganisms which are multiplying on a surface may be termed a ‘biofilm’—although the most well-recognized definition of a biofilm indicates the presence of a matrix of extracellular polymeric substances, a flowing aqueous environment and a solid-liquid interface, and hence may not be entirely applicable to all microorganisms on surfaces. It is therefore perhaps preferable to consider a given environment in terms of biotransfer potential, then to consider the mode in which microorganisms are present in order to develop appropriate models for monitoring and control procedures. The focus of this paper is on the diversity of forms in which the biotransfer potential may be presented, the aim being to recognize the limitations of the definition of the term biofilm, and the problems which might arise as a result of this misnomer.