Indicator Of Microbial Activity Research Articles

Application of Commercial Biopreservation Starter in Combination with MAP for Shelf-Life Extension of Burrata Cheese.

Burrata is a fresh pasta filata cheese manufactured in Italy. Its demand on the worldwide market is constantly growing, and prolonging its shelf-life is an important challenge for the Italian dairy industry. In the present study, combining a commercial bio-protective starter and modified atmosphere packaging (MAP) was evaluated as a strategy to delay the spoilage of product quality. Three experimental samples of burrata were produced by experimental trials at the industrial level and stored for 28 days under refrigerated conditions. Two samples contained the protective starter but were packaged differently (under MAP and immersed in water), and one did not contain the starter and was packaged under MAP. A sample of burrata without a starter and immersed in water was also prepared and used as a control. The combination of MAP and bio-protective starter delayed the degradation of lactose and citric acid, used as indices of microbial activity. In fact, lower counts of Enterobacteriaceae and Pseudomonas were observed in this sample. In contrast, control burrata had the highest level of total Volatile Organic Compounds (VOC) at the end of the storage period, because of higher microbial activity. Even though all samples were judged to be unacceptable after 28 days from the sensory point of view, the sample with bio-protective starter under MAP had the best score after 21 days, obtaining a shelf-life extension of about 7 days with respect to control. In conclusion, the combination of MAP and protective starter culture could be an easy way to extend the shelf-life of burrata stored under correct refrigerated conditions.

Changes in the activities of key enzymes and the abundance of functional genes involved in nitrogen transformation in rice rhizosphere soil under different aerated conditions

Soil microorganisms play important roles in nitrogen transformation. The aim of this study was to characterize changes in the activity of nitrogen transformation enzymes and the abundance of nitrogen function genes in rhizosphere soil aerated using three different methods (continuous flooding (CF), continuous flooding and aeration (CFA), and alternate wetting and drying (AWD)). The abundances of amoA ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB), nirS, nirK, and nifH genes; and the activities of urease, protease, ammonia oxidase, nitrate reductase, and nitrite reductase were measured at the tillering (S1), heading (S2), and ripening (S3) stages. We analyzed the relationships of the aforementioned microbial activity indices, in addition to soil microbial biomass carbon (MBC) and soil microbial biomass nitrogen (MBN), with the concentration of soil nitrate and ammonium nitrogen. The abundance of nitrogen function genes and the activities of nitrogen invertase in rice rhizosphere soil were higher at S2 compared with S1 and S3 in all treatments. AWD and CFA increased the abundance of amoA and nifH genes, and the activities of urease, protease, and ammonia oxidase, and decreased the abundance of nirS and nirK genes and the activities of nitrate reductase and nitrite reductase, with the effect of AWD being particularly strong. During the entire growth period, the mean abundances of the AOA amoA, AOB amoA, and nifH genes were 2.9, 5.8, and 3.0 higher in the AWD treatment than in the CF treatment, respectively, and the activities of urease, protease, and ammonia oxidase were 1.1, 0.5, and 0.7 higher in the AWD treatment than in the CF treatment, respectively. The abundances of the nirS and nirK genes, and the activities of nitrate reductase and nitrite reductase were 73.6, 84.8, 10.3 and 36.5% lower in the AWD treatment than in the CF treatment, respectively. The abundances of the AOA amoA, AOB amoA, and nifH genes were significantly and positively correlated with the activities of urease, protease, and ammonia oxidase, and the abundances of the nirS and nirK genes were significantly positively correlated with the activities of nitrate reductase. All the above indicators were positively correlated with soil MBC and MBN. In sum, microbial activity related to nitrogen transformation in rice rhizosphere soil was highest at S2. Aeration can effectively increase the activity of most nitrogen-converting microorganisms and MBN, and thus promote soil nitrogen transformation.

Estudio piloto para la inyección de bactericidas en arenas con problemas de actividad microbiana en el Campo Libertador, Bloque-57

Microbial activity can lead to problems such as corroded tubing, formation plugging, and decreased effective permeability, especially the sulfate-reducing bacteria that have the formation water as a medium that allows their proliferation. These adhere to the conductive channels of the producing sand and form biomass that restricts the flow of fluids. This work was carried out to design a non-reactive matrix stimulation by injecting biocides that clean the sand face to increase permeability, reduce formation damage, control corrosive environments, and increase daily oil production. By analyzing the total concentration of iron, sulfate, carbon dioxide, sulfide in gas and water, wells with microbial activity were identified, while the behavior of the bacteria was characterized by evaluating bacterial cultures and corrosion coupons. Using economic profitability criteria, the TTT A 011 and TAP 09 wells were selected as the most prospective in the Libertador field since, out of the 94 wells analyzed, they presented the highest index of microbial activity and recovery of oil barrels. The microbial activity in the wells of the Tetete station is more aggressive, since they reproduce in less time, clogging the porous channels at a faster rate. The THPS and GLH bactericides had better functionality against bacteria and the environment, so they were considered in this design of non-reactive matrix stimulation generating $907,976.10 as profit for the company in the 12-month projection.

The Effect of a Diet Containing Extruded Faba Bean Seeds on Growth Performance and Selected Microbial Activity Indices in the Large Intestine of Piglets.

Simple SummaryGrain legumes are cultivated for food and feed purposes in all regions of the world. Legumes are the main source of protein for a large part of the world population where animal protein is hardly available. The potential of grain legumes is increasing primarily due to the genetic improvement of their agricultural and nutritional characteristics and expansion of organic farming. They are also fed to animals as a component of concentrates and on farms producing “organic” food. Therefore, studies on the composition, nutritional value and factors affecting quality of legume protein contribute to a more efficient utilization of seeds as feed and food ingredients. Faba bean is rich in both starch and protein and is an important alternative protein source in animal nutrition; however, its potential is not yet fully exploited, particularly in pig diets. The aim of the study was to evaluate the effect of diets containing various levels of extruded faba bean seeds on growth performance and selected microbial activity indices in the large intestine of pigs. Treatments with faba bean seeds did not negatively affect growth performance (except for the highest level of faba bean) and microbial activity in the large intestine, and can be applied in piglet diets.The study investigated the effect of replacing soybean meal with extruded faba bean seeds on piglet growth performance and selected microbial activity indices in the large intestine. In total, 24, 35-day-old, healthy, castrated piglets of similar body weight were divided into four groups with six replicates. Animals in the control group (C) were fed with soybean meal without extruded faba bean seeds. In other experimental groups, pigs were fed diets with the addition of 20 (FB20), 25 (FB25) or 30% (FB30) extruded faba bean seeds instead of soybean meal and wheat starch. Growth performance, histology of the large intestine, short-chain fatty acids (SCFA) and ammonia concentration, as well as the activity of bacterial enzymes in digesta samples, were analyzed. The intake of the FB25 diet resulted in an increased feed:gain ratio in comparison to the FB30 group. Feeding the FB30 diet increased tunica muscularis thickness in the caecum as compared to other groups. Moreover, dietary inclusion of extruded faba bean seeds had no effect on SCFA and ammonia concentration. In addition, feeding diets with a different level of extruded faba bean seeds did not affect the activity of bacterial enzymes in the colon.

Microbial Dynamics and Nutrient Mineralization in Soil Amended with Cacao Pod and Water Hyacinth Composts: Implication for Nitrogen Fixed by Soybean

ABSTRACT Composting organic wastes can be relatively cheap and environmentally-friendly sources of mineralizable nutrients for legumes. We amended 5 kg topsoil (0–15 cm) samples of an Ultisol (Lixisol) with 0, 2.5 and 5 t ha−1 each of cacao pod (CC) and water hyacinth (WC) composts with and without starter fertilizer (F) (25 kg N ha−1 as urea and 26 kg P ha−1 as single super phosphate). The amended soil samples were used for 16-week laboratory incubation experiment and two-consecutive 8-week plantings of soybean (Glycine max. L. Merril) in the screenhouse. Measurements were carried out on some indices of microbial activity, namely, microbial respiration, N and P mineralization as well as on nodulation and N2 fixed by soybean. The microbial respiration, and N and P mineralization increased with application rates of the composts, but generally declined with incubation duration. Applications of 5 t ha−1 each of CC and WC with or without F increased (p < .05) the microbial respiration (24–93%), N mineralized (21–35%), and P mineralized (32–180%) during the incubation period. The highest of these increments was, however, obtained with WC. Increases of 1162 and 981% (CC2F and WC2F) and 28% (CC2F) were also recorded in nodulation and the amount of N2-fixed, respectively. It was concluded that 5 t ha−1 water hyacinth or cacao pod composts with starter fertilizer is capable of enhancing soybean N2 fixation by serving as mineralizable nutrient sources prior to the onset of nodulation and N2 fixation.

Persistence and degradation of cyantraniliprole in soil under the influence of varying light sources, temperatures, moisture regimes and carbon dioxide levels

In the present work, persistence and degradation of cyantraniliprole, a leading anthranilic diamide pesticide against sucking insect pests, in inceptisol soil has been studied. Effect of various factors like light source (UV-light, sunlight and dark), temperature (5, 25 and 37 °C), moisture regime (dry, field capacity and submerged) and carbon dioxide level (415 and 625 µL L−1) on dissipation was also evaluated. Formation of IN-J9Z38, a major metabolite of cyantraniliprole, was monitored in different treatments. Samples were processed as per QuEChERS method and analysis was done by HPLC-PDA. Matrix matched calibration curve, prepared in the range 0.001–10 mg L–1, indicated very good linearity (R2 > 0.99) and sensitivity (instrument limit of detection 0.001 mg L–1). Cyantraniliprole residues dissipated with time and 47.7%–98.8% dissipation was recorded on 90th day in different treatments. Minimum half-life of cyantraniliprole, i.e. 8.7 days was recorded at elevated CO2 level (625 ± 5 µL L−1) while its maximum half-life of 86.6 days was recorded at 5 °C. Metabolite IN-J9Z38 started forming from zero-day and reached the maximum on 15th to 60th day. Microbial biomass carbon, as an index of microbial activity of soil, correlated well with the degradation of cyantraniliprole.

Short‐Term Effects of Cover Crops on Soil Microbial Characteristics and Biogeochemical Processes across Actively Managed Farms

Core Ideas The effect of cover crops on soil microbes and biogeochemistry was examined. Cover crops increase microbial biomass and bioavailable soil carbon. Increasing cover crop biomass amplifies belowground effects. Agricultural soils are largely degraded or under threat of degradation. Given a growing human population and the subsequent need to feed this population, agricultural practices must maintain productivity and soil quality. Cover cropping regimes are a management approach that aims to address these dual goals. Although the use of cover crops has been linked to many positive effects on soil quality and crop yields, few studies have examined their effects on soil microbial community structure and function under active farm management. We assessed soil characteristics and microbial community structure and function between agricultural field plots with and without cover crops. We expected microbes would respond in the short‐term to increasing cover crop biomass, with increases in microbial activity and a shift in C acquisition toward substrates indicative of root exudation. In the presence of cover crops, we found active microbial biomass and bioavailable‐C increased by 64 and 37%, respectively, indicating the potential for increased C sequestration. Soil NH4+ increased by 64%, whereas soil NO3‐ decreased by 30%, indicating a shift toward less mobile N forms and the potential of greater nutrient retention under cover cropping regimes. Additionally, increasing cover crop biomass was related to lower microbial biomass C/N ratios and to decreased utilization of recalcitrant C substrates. These results potentially suggest a shift toward greater microbial utilization of root‐derived compounds with increasing cover crop biomass. Together, these results indicate that, in the short‐term, the presence of cover crops may improve soil quality, as measured by indices of microbial activity, and soil C and nutrients.

Physico-chemical and microbiological evidence of exposure effects on Picea abies – Coarse woody debris at different stages of decay

Although slope aspect determines the amount of solar irradiation, with implications on the functioning of forest ecosystems, little is known yet about how this affects the aboveground deadwood decomposition dynamics. Therefore, we set up a climosequence case study to evaluate the impact of slope exposure (north- vs. south-facing sites) on the physico-chemical and microbiological properties of Picea abies coarse woody debris (CWD) at different stages of natural decay (decay classes, DCls 1–5) in an Italian Alpine setting. Variations in bacterial, fungal and archaeal abundances were assessed by real-time PCR in the extra- and intracellular DNA fractions (eDNA vs. iDNA) of the total deadwood DNA pool. Physico-chemical wood properties (macro- and micronutrients; lignin and cellulose content; 3D structure via X-ray microtomography) were also performed along with the determination of key enzymatic activities involved in the main nutrient cycles. Overall, higher microbial abundances were registered in Picea abies CWD samples at the cooler, more acidic and moister north-facing site, which are favourable conditions especially for fungal wood decomposers. This thermal signal (N>S) was more evident for the advanced decay stages (DCls 4 and 5), being wood pH the most determinant factor for discriminating between both slopes. We also found that the impact of exposure was enzyme-specific and strongly dependent on the decay class, except for those enzymes involved in the P cycle. In addition, the eDNA/iDNA ratio provided a simple yet powerful index of microbial activity in terms of exposure, with lower values at the north-facing slope indicative of a higher microbial activity. This is in line with the more pronounced physical wood damage detected at this slope by the X-ray microtomography. A higher microbial activity at the cooler north-facing site rather seems surprising – a circumstance that probably is not due to temperature itself but due to increased moisture availability at this slope.

Plant residue and native organic matter decomposition under subsoil-specific gas conditions – Comparing topsoils with C-poor and C-rich subsoils

Decreasing O2 and increasing CO2 concentrations in the soil atmosphere with depth are one possible factor controlling C sequestration in subsoil. This study aimed to investigate the impact of these subsoil-specific gas conditions, which were measured in the field, on the decomposition of native soil organic C (SOC) and plant residues. Soil samples were taken on two neighbouring arable sites; one with high and the other with low SOC contents below 30cm depth. An incubation experiment was carried out for 176days, using gas conditions with reduced O2 and increased CO2, matching gas conditions measured in subsoil. Three different gas concentrations were used in the experiment: Ambient, medium (17% O2; 4% CO2) and extreme (13% O2; 8% CO2). These gas treatments were applied to samples with and without the addition of C4 plant residues to the sampled soil. We determined the effects of these treatments on contents of SOC, microbial biomass C (MBC) and fungal ergosterol. Plant residue addition caused negative priming effects on SOC mineralisation in the subsoils. The contribution of plant-derived to total MBC was reduced under medium and extreme gas conditions (topsoil: 31%; subsoil: 54%). However, neither medium nor extreme gas conditions had general effects on MBC and microbial activity indices. There was no evidence that changes in the soil atmosphere are a major factor controlling C sequestration in subsoil. However, some results indicate that changes in soil atmospheric conditions do have an impact on microbial substrate use, which should be considered in C sequestration research in subsoil.

Effect of Replacing Soybean Meal by Raw or Extruded Pea Seeds on Growth Performance and Selected Physiological Parameters of the Ileum and Distal Colon of Pigs.

The use of pea seeds is limited due to the content of antinutritional factors that may affect gut physiology. Heat treatment such as extrusion may reduce heat-labile antinutritional factors and improve the nutritional value of pea seeds. This study determined the effect of partial replacement of soybean meal in pig diets by raw or extruded pea seeds on growth performance, nitrogen balance and physiology of the ileum and distal colon. The experiment was carried out in 18 castrated male piglets of initial body weight of 11 kg, divided into three groups. The animals were fed cereal-based diets with soybean meal (C), which was partly replaced by raw (PR) or extruded pea (PE) seeds. Nitrogen balance was measured at about 15 kg body weight. After 26 days of feeding, tissue samples were taken from the ileum and distal colon for histological measurements, and colonic digesta samples for analyses of microbial activity indices. The animals fed the PE diet had a significantly greater average daily gain than those fed the C diet and better apparent protein digestibility than those on the PR diet. Pigs fed the PR diet had a significantly greater butyric acid concentration and lower pH in the colon than pigs fed PE and C diets. There was no significant effect of the diet on other indices of microbial activity or morphological parameters. In conclusion, feeding a diet with extruded pea seeds improved growth performance of pigs, did not affect intestinal morphology and had a negligible effect on microbial activity in the distal colon.

Microbial Activity in the Large Intestine of Chicks Fed Diets with Different Types and Levels of Inulin

Abstract The aim of the study was to evaluate the effects of dietary level of two types of inulin differing in the degree of polymerization (DP) on microbial activity in the large intestine of chicks. The experiment was performed on 70 one-day-old Ross 308 male chicks divided into 7 groups fed starter-type diets without inulin addition or supplemented with 0.2%, 0.4% or 0.6% of inulin with DP≥10 (IN10), or DP≥23 (IN23). After 14 days of feeding birds were sacrificed to collect digesta samples from caeca and colon. Caecal digesta was examined for pH, concentrations of short-chain fatty acids (SCFA) and amines, activities of β-glucosidase and mucinase, and relative amount of selected bacterial populations, whereas in colonic digesta only pH, SCFA and amines were analysed. Regardless of DP, inulin level did not affect digesta pH, activity of bacterial enzymes and relative amounts of Clostridium spp., Lactobacillus spp., Bifidobacterium spp. and E. coli populations. Dietary level of IN10 significantly affected propionic acid concentration, which was greater in caecal digesta of birds fed diet supplemented with 0.2% of IN10 compared to other groups and feeding diets supplemented with all levels of IN10 significantly reduced histamine concentration compared to the control. There were no effects of inulin on microbial activity indices in the colon. The present study indicates that, regardless of DP, inulin does not modify considerably microbial activity in the large intestine of chicks.

Respiration and enzymatic activities as indicators of stabilization of sewage sludge composting

The objective of this work was to study the evolution of physico-chemical and microbial parameters in the composting process of sewage sludge (SS) with pruning wastes (PW) in order to compare these parameters with respect to their applicability in the evaluation of organic matter (OM) stabilization. To evaluate the composting process and organic matter stability, different microbial activities were compared during composting of anaerobically digested SS with two volumetric ratios, 1:1 and 3:1 of PW:SS and two aeration techniques including aerated static piles (ASP) and turned windrows (TW). Dehydrogenase activity, fluorescein diacetate hydrolysis, and specific oxygen uptake rate (SOUR) were used as microbial activity indices. These indices were compared with traditional parameters, including temperature, pH, moisture content, organic matter, and C/N ratio. The results showed that the TW method and 3:1 (PW:SS) proportion was superior to the ASP method and 1:1 proportion, since the former accelerate the composting process by catalyzing the OM stabilization. Enzymatic activities and SOUR, which reflect microbial activity, correlated well with temperature fluctuations. Based on these results it appears that SOUR and the enzymatic activities are useful parameters to monitor the stabilization of SS compost.

Impact of ecological and conventional farming systems on chemical and biological soil quality indices in a cold mountain climate in Slovakia

There is a need to assess the impact of different farming methods on soil quality and fertility in specific ecoregions. Soil biochemical parameters and soil enzymatic activity appear very useful in monitoring soil pollution and management practices and can be used as indicators of sustainability. Soil chemical properties, biological properties and soil enzymatic activity (urease, acid and alkaline phosphatase) were investigated at six sites under ecological farming (no pesticides, organic fertilizers and crop rotation) and six sites under a conventional farming (pesticides and mineral fertilizers) system. A comparative study was performed during years 2008–2011 under production conditions in the investigated areas, situated in the marginal region of north-eastern Slovakia. Research showed that high doses of organic fertilizers had positive effect on soil productivity, and thus indirectly on maintaining soil pH and accumulation of humus in soil. The values of soil enzyme activities changed minimally during the research period. Statistically significant effect of experimental year and locality on all observed soil parameters was confirmed by analysis of variance. Large differences between the two sites were found in terms of microbiological properties, which are sensitive soil indicators of changes occurred under different farming systems. The study confirmed the positive influence and higher microbial activity indices of ecological farming (36% higher enzymatic activity, 65% higher soil respiration content, 60% higher soil microbial biomass carbon content) compared with conventional farming system.

Microbial Response to Fertilization in Contrasting Soil Materials used during Oil Sands Reclamation

Reclamation practices following open‐pit mining typically include the reconstruction of soil‐like profiles using a combination of native soil materials, industrial by‐products, and fertilizers. Our overall objective was to compare the quality of eight soil materials used during reclamation in the Athabasca oil sands region of western Canada by characterizing their microbial communities as well as their response to a range of fertilization treatments. Materials included two carbon‐rich surface soil materials, four B horizons with varying extractable phosphorus and pH, the parent geological material (PGM), and tailings sands (TSS), a by‐product of oil extraction. Measured indices of microbial activity included the activities of b‐glucosidase, acid phosphatase, and phenol oxidase. Total biomass and structure of the soil microbial community were characterized based on phospholipid fatty acid (PLFA) analysis. Soil materials and fertilization treatments were tested with multivariate regression trees and non‐metric multidimensional scaling. Material type, rather than fertilization level, had the largest impact on all microbial parameters, including biomass, activity, and composition. Only the nutrient‐poor materials (PGM, TSS, and one of the B horizons) showed a response to fertilization. The microbial composition of three of the four B horizons was more similar to the two carbon‐rich surface soil materials than it was to PGM or TSS. Hence, we propose that these subsoil materials present an advantage over the use of the underlying PGM when reconstructing upland sandy soils. Finally, results indicated that soil microbial biomass could be used as a good indicator of seedling growth when no fertilizer was applied.

Effects of nonylphenols on soil microbial activity and water retention

The main aim of this study is to analyze the influence of 4-nonylphenol (NP) on soil water retention and biological activity. Two doses of 4-nonylphenol (25 and 50mgkg−1) were tested in a loam soil with and without peat amendment. In general, one week after the start of the experiment, the soil water content retained at −0.75MPa of soil suction was 18% higher in the soil amended and its basal respiration (BR) was 15% higher than soil without peat. In contrast, the microbial activity indices (CM: coefficient of mineralization or BR:total organic carbon (TOC) ratio; Cmic:Corg: microbial biomass carbon (MBC):TOC ratio; qCO2: metabolic quotient or BR:MBC ratio) were higher in the soil without peat, compared to the soil amended with peat. On the other hand, the addition of NP to soil was able to modify soil biological but not physical (water retention, desorption) properties. When soil was amended with peat, MBC was reduced one week after applying NP. In contrast, no effects of NP on MBC were observed in the soil without peat. BR was reduced by 16% one week after applying 50mgkg−1 of NP to soil with peat, and was increased by 46% one week after applying 25mgkg−1 of NP to soil without peat. The effects of NP on MBC and BR could be associated more with the adsorption of NP by soil organic matter, while changes in CM or Cmic:Corg ratio were more closely related to changes in soil water retention. The potential toxic effects of NP (high qCO2 values) were only observed in the absence of peat amendments. Peat addition reduced NP toxic effects on microorganisms.

Integrating genomics, transcriptomics, proteomics, and metabolomics into environmental enzymology: the next frontier or fool's gold?

AbstractExtracellular enzymes are widely measured as indices of microbial activity, resource allocation, and substrate availability. However, interpretation of enzyme activities is hampered by a limited understanding of controls on enzyme production, turnover, and in-situ activity. In part, this is the consequence of methodological limitations, which require artificial substrates and are conducted under conditions that differ from in situ conditions. Recently, new tools have emerged that have potential to provide new insights into microbial enzymology. Will these methods open a new frontier in enzymology research, or will they only result in the discovery of fool’s gold? I will highlight how genomic, transcriptomic, proteomic, and metabolomic tools might be used to gain new insights into the controls on enzyme production, turnover, and in-situ activity. I will also discuss the potential for significant advancements even without the use of emerging tools. Each of these techniques offers the potential to provide new pieces to the puzzle of environmental enzymology, but progress is most likely through a multi-faceted approach.

Comparison of culture and nucleic acid amplification methods for diagnosis of tuberculosis of the dorsal spine

Introduction Neurological complications in paucibacillary spine tuberculosis can be minimized or prevented if an etiology is available in the early stage of the disease for effective clinical management. Polymerase chain reaction (PCR) is a rapid diagnostic tool overriding the limitations of direct microscopy, culture and serology for Mycobacterium tuberculosis. Agent specific positive PCR in samples from normally sterile body sites is an index of microbial activity. Methods We report the correlation between PCR and classical methods in 27 patients with tuberculosis of the dorsal spine undergoing anterior decompression and anterolateral decompression. Tissue samples collected at surgery were used for laboratory methods. Results Acid fast bacilli were demonstrated in four (14.8%) patients by staining. Culture was positive in three (11.11%) only, of whom one had been on antitubercular treatment (ATT) for 4 days while the rest had not been on any drugs. Culture and direct microscopy together could identify only six of the 27 patients. Fluctuation in IgM and IgG titres at admission and 3 months postoperatively was statistically significant. Serology did not correlate with the duration of ATT. PCR was positive in 26 (96.2%) of the patients, all of whom had histological features suggestive of tubercular osteomyelitis, including the PCR negative patient. Etiological diagnosis by all the methods, viz., PCR, AFB staining, culture and serology was positive in one patient only. Conclusion For diagnosis of spine tuberculosis, nucleic acid amplification methods either alone or in combination with classical methods offer a better prospect of early case detection and intervention.

Influence of conservation tillage and crop rotation on the resilience of an intensive long-term potato cropping system: Restoration of soil biological properties after the potato phase

Conservation tillage in potato ( Solanum tuberosum L.) systems, in cool-humid climatic regions, can benefit soil physical and biological properties. However, insight is needed on how the combination of conservation tillage and crop rotation enhances the resilience of intensive short-term potato cropping systems, specifically the restoration of the soil condition after the perturbations that occur in the potato phase. A long-term 3-year rotation (potato-barley-red clover) and conservation tillage study was initiated in 1994 on a fine sandy loam in Prince Edward Island, eastern Canada. Over a 3-year period (2004–2006), soil physical (bulk density) and biological (C and N fractions, structural stability; densities of plant parasitic and bacterial-feeding nematodes, and micro-arthropod abundance and diversity) properties were monitored over each phase of the crop rotation cycle to assess the restoration or rejuvenation of the surface (0–10 cm) soil condition. Conservation compared to conventional tillage, increased soil organic C, large water-stable macro-aggregates, and soil particulate C and N in the potato year only. After the potato phase, rotation crops were associated with the further restoration of all soil C and N fractions and soil structural stability indices; and also increases in soil microbial biomass C and microbial activity indices, and soil Collembola abundance. Soil nematode densities showed some incidences of treatment differences but no clear trends. The study indicated that conservation tillage has a positive influence on soil biological properties and that the 3-year rotation successfully restored many of the soil parameters that had declined in the potato year.

Microbial biomass and activity in alkalized magnesic soils under arid conditions

The effects of salinity and Mg 2+ alkalinity on the size and activity of the soil microbial communities were investigated. The study was conducted along the border area of the alluvial fan of the Taolai River. Thirty soil samples were taken which had an electrical conductivity (EC) gradient of 0.93–29.60 mS cm −1. Soil pH ranged from 8.60 to 9.33 and correlated positively with Mg 2+/Ca 2+ ratio, exchangeable Mg 2+ percentage and HCO 3 −+CO 3 2−. Mg 2+/Ca 2+ varied considerably from 3.04 to 61.31, with an average of 23.03. Exchangeable Mg 2+ percentage generally exceeded 60% and had a positive correlation with Mg 2+/Ca 2+. HCO 3 −+CO 3 2− averaged 1.63 cmol kg −1 and usually did not exceed 2.0 cmol kg −1. Microbial biomass, indices of microbial activity and the activities of the hydrolases negatively correlated with Mg 2+/Ca 2+ or exchangeable Mg 2+ percentage. Biomass C, biomass N, microbial quotient (the percentage of soil organic C present as biomass C), biomass N as a percentage of total N, potentially mineralizable N, FDA hydrolysis rate and arginine ammonification rate decreased exponentially with increasing EC. The biomass C/N tended to be lower in soils with higher salinity and Mg 2+ alkalinity, probably reflecting the bacterial dominance in microbial biomass in alkalized magnesic soils. The metabolic quotient ( qCO 2) positively correlated with salinity and Mg 2+ alkalinity, and showed a quadratic relationship with EC, indicating that increasing salinity and Mg 2+ alkalinity resulted in a progressively smaller, more stressed microbial communities which was less metabolically efficient. Consequently, our data suggest that salinity and Mg 2+ alkalinity are stressful environments for soil microorganisms.

Influence of metalaxyl- and mefenoxam-based fungicides on chemical and biochemical attributes of soil quality under field conditions in a southern humid forest zone of Cameroon

A field experiment was conducted to study the changes in the chemical and biochemical attributes of soil quality resulting from a single application of metalaxyl- and mefenoxam-based fungicides applied as their EC and WPC formulations at the commercially recommended application rate under tropical rainforest field conditions. No significant change in soil pH was observed with fungicide application. Microbial activity indices (available P, available N and specific enzymatic systems) were more sensitive indicators of change. Acid and alkaline phosphatase, and β-Glucosidase activities in soil were affected at different levels with application of fungicides. However, use of metalaxyl and mefenoxam is not likely to harm the soil quality, in general. Simple correlations done between physico-chemical and microbial properties did not produce any significant relationship.