The effect of high microbial populations on the physical properties of kaolin slurries

Large populations of microorganisms were shown to have little or no effect on the physical properties of kaolin slurries. The physical properties that were measured were brightness, soluble salts, pH, and viscosity. This was found to be the case when autoclaved samples of kaolin slurries were inoculated with strains of Pseudomonas putida, an organism frequently encountered in kaolin slurries, and incubated for five weeks; or, when uninoculated samples of kaolin slurries, and incubated for five weeks; or, when uninoculated samples of kaolin slurries were incubated for as long as three months to allow the naturally occurring contaminating organisms to grow. In each case, from 10⁵ to over 10⁷ colony forming units ml⁻¹ developed. In several instances, however, the viscosity increased slightly but within acceptable limits.When kaolin slurries were inoculated with massive numbers of microorganisms in their own spent media, the viscosity increased significantly over a period of five weeks in some, but not all, cases. Brightness, pH and soluble salts content, however, did not change. It was probable that microbial slime material in the spent media plus additional slime material formed owing to the introduction of nutrients from the spent media into the kaolin slurries contributed to the increase in viscosity. The increase in viscosity took place sufficiently slowly, however, that under normal, practical working circumstances the kaolin slurries would have been used before the increase in viscosity became apparent. Moreover, the numbers of microorganisms used in these experiments were more than an order of magnitude greater than that which would develop naturally in kaolin slurries not treated with preservatives.It was concluded from these experiments that under normal conditions high numbers of microorganisms would have little or no effect on the physical properties of kaolin.     

Viability of zoonotic pathogens Escherichia coli and Salmonella in swine manure slurries with and without a urease inhibitor and thymol

Aims: To determine the effects of urine, a urease inhibitor and/or an odour‐reducing antimicrobial compound, on zoonotic pathogens in swine manure slurries. Methods and Results: Swine faeces were collected and blended with different amounts of urine. Marker strains of Salmonella enterica subsp. enterica serovar Typhimurium and Escherichia coli O157:H7 were inoculated into the manure slurries with or without the urease inhibitor, N‐(n‐butyl) thiophosphoric triamide, or the antimicrobial compound thymol. In slurries containing approximately 1 : 1 or 2 : 1 of urine and faeces, the decreases in colony forming units (CFU) of Salm. Typhimurium and E. coli were similar and few counts were observed after 14 days. When the urine content of the slurry was increased to 5 : 1, both strains died off rapidly. When NBPT was added to the slurries, pathogen CFU was not affected in the 1 : 1 slurry. The 2 : 1 and 5 : 1 slurries had higher urea content and NBPT increased CFU of both pathogens. Thymol addition rapidly killed the pathogens and few CFU of Salmonella or E. coli were observed after day 1. Conclusions: These experiments demonstrate that urea hydrolysis in swine manure affects pathogens. Inhibition of urea hydrolysis may promote pathogen viability. Significance and Impact of the Study: Manure amendments that prevent urea hydrolysis may promote pathogen persistence. Additional treatments with antimicrobials may be required to kill pathogens.     

Evaluation of a method to measure conjugal transfer of recombinant DNA in soil slurries

Release of recombinant microbes into the environment necessitates an evaluation of their ability to transfer genetic material. The present report evaluates a method to detect conjugal DNA plasmid transfer in soil slurries under various environmental conditions. DonorPseudomonas cepacia containing pR388::Tn1721 andP. cepacia recipient cultures were coincubated in soil slurries containing autoclaved or natural soil and treated with one or more of 14 experimental conditions. Conjugal mating frequency (transconjugants per initial donor) ranged from 4.8×10^–1 to 1.9×10^–7. Highest numbers of transconjugants, 1.5×10⁷ colony forming units/ml soil slurry, were observed following incubation at 35°C with an enriched nutrient supplement added to the soil. Low numbers of transconjugants, 10³ colony forming units/ml soil slurry, were observed when mating pairs were subjected to low nutrient or pH stress even though initial donor and recipient populations were maintained at high levels. This test system provides a simple way to estimate effects of changing environmental factors on plasmid transfer rates and on the survival of recombinant microorganisms. By use of soil collected from sites proposed to receive genetically engineered microorganisms, preliminary risk assessments can be obtained regarding the potential for gene transfer and microorganism survival with this soil slurry test system.     

The effect of low pressure-homogenized lactic cultures on the development of proteolysis in cheese slurry

Summary The aim of this study was to determine the effect of low pressure-homogenization of lactic acid bacteria (LAB) on the development of proteolysis in the slurry medium. For the slurry, the milk was pasteurized at 65 °C for 30 min, cooled to 32 °C and coagulated. The curd obtained was blended; the dry matter was adjusted to 30% by adding distilled water, placed into the flasks and autoclaved. The LAB Lactococcus lactis subsp. lactis, Lactococcus lactis subsp. cremoris, Lactobacillus delbrueckii subsp. bulgaricus, Streptococcus thermophilus, and Lactobacillus helveticus were used in cheese slurry. Homogenization was performed at 30 MPa and 40 °C. The cheese slurries were incubated with and without homogenized cultures at 9 and 30 °C for up to 72 h. During incubation, the changes in trichloroacetic acid-soluble nitrogen (TCA-SN) and phosphotungstic acid-soluble nitrogen (PTA-SN) as well as pH were monitored. The results showed that pH development was slower in the slurries to which homogenized culture was added. Higher TCA-SN and PTA-SN values were obtained from the slurries incubated at 30 °C. Moreover, higher TCA-SN and PTA-SN values were found in the slurries incubated with homogenized mesophilic culture and Lb. helveticus (P<0.05). The results suggested that homogenization of the cultures was a promising method for the acceleration of cheese ripening.     

The use of chemical profiling for monitoring metabolic changes in artificial soil slurries caused by horizontal gene transfer

This study explores the utility of Fourier transform infra-red spectroscopy (FT-IR) as a metabolomic tool to detect changes in water-extractable chemical profile resulting from horizontal gene transfer (HGT) events in artificial soil slurries. A GFP–Km (Green fluorescent protein–kanamycin) cassette tagged HGT recipient Acinetobacter strain ADPWH67 with the salicylate hydroxylase gene (salA) disrupted was introduced to slurries containing either sterile or non-sterile soil. The subsequent addition of naked salA DNA allowed the specific monitoring of HGT events by enumerating GFP-expressing colonies on minimal media with salicylate as a sole carbon source. DNA sequencing confirmed that salA was restored in these transformants. Gene transformation frequencies of around 10⁻⁶ were achieved in the presence of sterile and non-sterile soils. Aqueous extracts of the soil slurries were then analyzed using FT-IR in order to ascertain whether any shifts in chemical profile could be detected. We found that following HGT events FT-IR chemical profiles were clearly altered when analyzed with multivariate statistics. Furthermore, these changes could be explained by differences in key chemical signatures including salicylate as well as other biomolecules found in soils. The slurry extracts were also subjected to GC-MS which confirmed the results of FT-IR analyses. FT-IR was therefore demonstrated to have utility for the rapid screening of metabolomic changes in soils following effective HGT events. In addition, this approach could potentially link specific metabolite changes with corresponding catabolic genes.Electronic Supplementary Material Supplementary material is available for this article at and is accessible for authorized users.     

Degradation of chloroanilines in soil slurry by specialized organisms

The microbial degradation of 2-chloro-, 3-chloro-, 4-chloro-, and 3,4-dichloroaniline was examined as single compounds as well as a mixture in soil slurries. At 30°C the degradation of chloroanilines by indigenous soil populations in soil slurries was observed when soil slurry was freshly contaminated or precontaminated to allow binding of chloroanilines to the soil matrix. Within 6 weeks, 3-chloro- and 3,4-dichloroaniline (each 2 mm) were degraded more rapidly (about 50% chloride elimination) than 4-chloro- and 2-chloroaniline, due to stronger adsorption of 4-chloroaniline and greater resistance of 2-chloroaniline. The addition of various supplements such as buffer, mineral salts and acetate only slightly influenced the degradation of chloroanilines by the indigenous soil populations. The mineralization was drastically enhanced when laboratory-selected chloroaniline-degraders (8·10⁶ cells/g) such as Pseudomonas acidovorans strain BN3.1 were supplemented to the soil slurries so that complete elimination of chloride from the chloroanilines occurred within 10 days. Correspondence to: F. R. Brunsbach     

Enhanced lindane removal from soil slurry by immobilized Streptomyces consortium

The aim of this work was to assess lindane removal from soil slurry by a Streptomyces consortium immobilized in cloth sachets, at different inoculum, lindane and slurry concentrations. In concentrated slurry (soil/water ratio of 2:3), the higher lindane removal (35.3 mg Kg⁻¹) was obtained with the medium inoculum (10⁷ CFU g⁻¹) and the highest lindane concentration tested, at 7 days of incubation. Although, lindane removal was also detected in abiotic controls, probably caused by pesticide adsorption to soil particles. Thus, these parameters were selected for evaluating the pesticide removal in diluted slurry (soil/water ratio of 1:4). After 14 days of incubation, 28.7 mg Kg⁻¹ of lindane were removed. Also, a phytotoxicity assay demonstrated that seeds growing on diluted slurries bioremediated during 7 and 14 days, showed an improvement in biological parameters, compared to those growing on non-bioremediated slurries. Thus, bioremediated slurries would not have toxic effects on lettuce seeds.     

Effect of fermentation temperature on hydrogen production from cow waste slurry by using anaerobic microflora within the slurry

We examined hydrogen production from a dairy cow waste slurry (13.4 g of volatile solids per liter) by batch cultures in a temperature range from 37 to 85°C, using microflora naturally present within the slurry. Without the addition of seed bacteria, hydrogen was produced by simply incubating the slurry, using the microflora within the slurry. Interestingly, two peaks of fermentation temperatures for hydrogen production from the slurry were observed at 60 and 75°C (392 and 248 ml H₂ per liter of slurry, respectively). After the termination of the hydrogen evolution, the microflora cultured at 60°C displayed hydrogen-consuming activity, but hydrogen-consuming activity of the microflora cultured at 75°C was not detected, at least for 24 days. At both 60 and 75°C, the main by-product was acetate, and the optimum pH of the slurry for hydrogen production was around neutral. Bacteria related to hydrogen-producing moderate and extreme thermophiles, Clostridium thermocellum and Caldanaerobacter subterraneus, were detected in the slurries cultured at 60 and 75°C, respectively, by denaturing gradient gel electrophoresis analyses, using the V3 region of 16S rDNA.     

Digestion of sand-laden manure slurry in an upflow anaerobic solids removal (UASR) digester

Studies on the performance of a laboratory scale upflow anaerobic solids removal (UASR) digester were carried out using sand-laden cow manure slurries having total solids (TS) concentration as 50 and 100 g/l. Hydraulic retention time (HRT) was maintained as 32.4 days, which resulted in the volatile solids (VS) loading rates of 1 and 1.64 g/l d. The UASR system was designed to remove sand from the manure slurry, while anaerobically digesting biodegradable solids inside a single reactor. To enhance the contact of microorganisms and substrate, the liquor from the top of the digester was recirculated through the bed of settled solids at its bottom. Volatile solids reduction through this process was observed to be 62% and 68% in the case of feed slurries having TS concentration as 50 and 100 g/l (referred in the text as 5% and 10% feed slurries), respectively. The methane production rates were observed to be 0.22 and 0.38 l/l d, while methane yield was 0.21 and 0.27 l CH₄/g VS loaded, for 5% and 10% feed slurries, respectively. This indicates that the increase in the VS loading had a positive impact on methane production rate and methane yield. It would be of interest to study the performance of a UASR digester at higher solids loadings and with longer solids retention times. Nonetheless, the presented study showed that sand-laden manure slurries can be successfully digested in a UASR digester producing methane energy equivalent to 4 kW h per m³ of digester volume per day.     

Use of Hydrostatic Pressure for Inactivation of Microbial Contaminants in Cheese

The objective of this study was to determine the effect of high pressure (HP) on the inactivation of microbial contaminants in Cheddar cheese (Escherichia coli K-12, Staphylococcus aureus ATCC 6538, and Penicillium roqueforti IMI 297987). Initially, cheese slurries inoculated with E. coli, S. aureus, and P. roqueforti were used as a convenient means to define the effects of a range of pressures and temperatures on the viability of these microorganisms. Cheese slurries were subjected to pressures of 50 to 800 MPa for 20 min at temperatures of 10, 20, and 30°C. At 400 MPa, the viability of P. roqueforti in cheese slurry decreased by >2-log-unit cycles at 10°C and by 6-log-unit cycles at temperatures of 20 and 30°C. S. aureus and E. coli were not detected after HP treatments in cheese slurry of >600 MPa at 20°C and >400 MPa at 30°C, respectively. In addition to cell death, the presence of sublethally injured cells in HP-treated slurries was demonstrated by differential plating using nonselective agar incorporating salt or glucose. Kinetic experiments of HP inactivation demonstrated that increasing the pressure from 300 to 400 MPa resulted in a higher degree of inactivation than increasing the pressurization time from 0 to 60 min, indicating a greater antimicrobial impact of pressure. Selected conditions were subsequently tested on Cheddar cheese by adding the isolates to cheese milk and pressure treating the resultant cheeses at 100 to 500 MPa for 20 min at 20°C. The relative sensitivities of the isolates to HP in Cheddar cheese were similar to those observed in the cheese slurry, i.e., P. roqueforti was more sensitive than E. coli, which was more sensitive than S. aureus. The organisms were more sensitive to pressure in cheese than slurry, especially with E. coli. On comparison of the sensitivities of the microorganisms in a pH 5.3 phosphate buffer, cheese slurry, and Cheddar cheese, greatest sensitivity to HP was shown in the pH 5.3 phosphate buffer by S. aureus and P. roqueforti while greatest sensitivity to HP by E. coli was exhibited in Cheddar cheese. Therefore, the medium in which the microorganisms are treated is an important determinant of the level of inactivation observed.     

Quantitative microbial indices in biogas and raw cattle slurries

Biogas slurry, the secondary product of the anaerobic digestion process, is increasingly being used as fertilizer. Information is available on its chemical and physical properties and their effects on plant growth. However, there is a demand to characterize the microbial quality of slurries, which may control further mineralization processes after application to soil. In this study, biogas and raw slurries obtained from six farms were analyzed for their ergosterol and amino sugar concentrations as indices for microbial biomass. A reliable, precise method for determining ergosterol in slurries is presented. Biogas slurries contained significantly less ergosterol (?34%), muramic acid (MurN; ?42%), galactosamine (GalN; ?32%), and fungal glucosamine (GlcN; ?40%) than raw slurries. The mean fungal GlcN to ergosterol ratio (50) and also the mean fungal carbon (C) to bacterial C ratio (0.29) did not significantly differ between the slurry types. The mean microbial C concentration in the biogas slurries was significantly lower than in the raw slurries. Consequently, the contribution of microbial C to slurry organic C was 3.6% in the biogas slurries and 5.7% in the raw slurries. Microbial C revealed significant nonlinear relationships with the fiber and ash concentration, pH, as well as the C/N ratio of the slurries.     

Optimization of environmental parameters for biodegradation of alpha and beta endosulfan in soil slurry by Pseudomonas aeruginosa

Aim: To determine optimal environmental conditions for achieving biodegradation of α‐ and β‐endosulfan in soil slurries following inoculation with an endosulfan degrading strain of Pseudomonas aeruginosa. Methods and Results: Parameters that were investigated included soil texture, soil slurry: water ratios, initial inoculum size, pH, incubation temperature, aeration, and the use of exogenous sources of organic and amino acids. The results showed that endosulfan degradation was most effectively achieved at an initial inoculum size of 600 μl (OD = 0·86), incubation temperature of 30°C, in aerated slurries at pH 8, in loam soil. Under these conditions, the bacterium removed more than 85% of spiked α‐ and β‐endosulfan (100 mg l^?1) after 16 days. Abiotic degradation in noninoculated control medium within same incubation period was about 16%. Biodegradation of endosulfan varied in different textured soils, being more rapid in course textured soil than in fine textured soil. Increasing the soil contents in the slurry above 15% resulted in less biodegradation of endosulfan. Exogenous application of organic acids (citric acid and acetic acid) and amino acids (l ‐methionine and l ‐cystein) had stimulatory and inhibitory effects, respectively, on biodegradation of endosulfan. Conclusion: The results of this study demonstrated that biodegradation of endosulfan by Ps. aeruginosa in soil sediments enhanced significantly under optimized environmental conditions. Significance and Impact of the Study: Endosulfan is a commonly used pesticide that can contaminate soil, wetlands and groundwater. Our study demonstrates that bioaugmentation of contaminated soils with an endosulfan degrading bacterium under optimized conditions provides an effective bioremediation strategy.     

Plasmid transfer between strains of Pseudomonas putida, and their survival, within a pilot scale percolating-filter sewage treatment system

Abstract: The effect of Pseudomonas aeruginosa UG2 biosurfactants or UG2 inocula on phenanthrene mineralization in uninoculated nonsterile soil slurries and slurries inoculated with the phenanthrene-mineralizing Pseudomonas sp. UG14r was investigated. In sandy loam and silt loam slurries amended with phenanthrene, inoculation with UG14r alone or in co-culture with UG2Lr reduced the lag period before onset of phenanthrene mineralization by 1 week. The total amount mineralized after 5 weeks was lower or not significantly different from the uninoculated control slurries. Inoculation with P. aeruginosa UG2Lr alone did not improve phenanthrene mineralization. In creosote-contaminated soil slurries, no lag period in phenanthrene mineralization was observed in any treatment. After 4 weeks, the greatest extent of mineralization was observed in creosote-contaminated soil slurries inoculated with the UG14r-UG2Lr co-culture and UG14r alone. In sandy loam and silt loam soil slurries inoculated with Pseudomonas sp. UG14r, addition of UG2 rhamnolipid biosurfactants (100 to 400 mg rhamnose equivalents (RE) · l⁻¹ slurry) inhibited phenanthrene mineralization by 10 to 15%. Mineralization was also inhibited in uninoculated sandy loam slurries. In creosote-contaminated soil slurries inoculated with Pseudomonas sp. UG14r, biosurfactants at 250 mg RE · l⁻¹ slurry enhanced mineralization whereas 400 mg RE · l⁻¹ had no effect, compared to unamended slurries. In uninoculated creosote-contaminated soil slurries, UG2 biosurfactants at 250 and 400 mg RE · l⁻¹ slurry enhanced mineralization, compared to unamended slurries.     

The Impact of Using Alternative Forages on the Nutrient Value within Slurry and Its Implications for Forage Productivity in Agricultural Systems

Alternative forages can be used to provide valuable home-grown feed for ruminant livestock. Utilising these different forages could affect the manure value and the implications of incorporating these forages into farming systems, needs to be better understood. An experiment tested the hypothesis that applying slurries from ruminants, fed ensiled red clover (Trifolium pratense), lucerne (Medicago sativa) or kale (Brassica oleracea) would improve the yield of hybrid ryegrass (Lolium hybridicum), compared with applying slurries from ruminants fed ensiled hybrid ryegrass, or applying inorganic N alone. Slurries from sheep offered one of four silages were applied to ryegrass plots (at 35 t ha⁻¹) with 100 kg N ha⁻¹ inorganic fertiliser; dry matter (DM) yield was compared to plots only receiving ammonium nitrate at rates of 0, 100 and 250 kg N ha⁻¹ year⁻¹. The DM yield of plots treated with 250 kg N, lucerne or red clover slurry was significantly higher than other treatments (P<0.001). The estimated relative fertiliser N equivalence (FNE) (fertiliser-N needed to produce same yield as slurry N), was greatest for lucerne (114 kg) >red clover (81 kg) >kale (44 kg) >ryegrass (26 kg ha⁻¹ yr⁻¹). These FNE values represent relative efficiencies of 22% (ryegrass), 52% (kale), 47% (red clover) and 60% for lucerne slurry, with the ryegrass slurry efficiency being lowest (P = 0.005). Soil magnesium levels in plots treated with legume slurry were higher than other treatments (P<0.001). Overall, slurries from ruminants fed alternative ensiled forages increased soil nutrient status, forage productivity and better N efficiency than slurries from ruminants fed ryegrass silage. The efficiency of fertiliser use is one of the major factors influencing the sustainability of farming systems, these findings highlight the cascade in benefits from feeding ruminants alternative forages, and the need to ensure their value is effectively captured to reduce environmental risks.     

Transformations of TNT and related aminotoluenes in groundwater aquifer slurries under different electron-accepting conditions

The transport and fate of pollutants is often governed by both their tendency to sorb as well as their susceptibility to biodegradation. We have evaluated these parameters for 2,4,6-trinitrotoluene (TNT) and several biodegradation products. Slurries of aquifer sediment and groundwater depleted TNT at rates of 27, 7.7 and 5.9 μM day⁻¹ under methanogenic, sulfate-reducing and nitrate-reducing conditions, respectively. Abiotic losses of TNT were determined in autoclaved controls. Abiotic TNT loss and subsequent transformation of the products was also observed. These transformations were especially important during the first step in the reduction of TNT. Subsequent abiotic reactions could account for all of the transformations observed in bottles which were initially nitrate-reducing. Other controls removed TNT reduction products at much slower rates than slurries containing live organisms. 2-Amino-4,6-dinitrotoluene was produced in all slurries but disappeared in methanogenic and in sulfate-reducing slurries within several weeks. This compound was converted to 2,4-diamino-6-nitrotoluene in all slurries with subsequent removal of the latter from methanogenic and sulfate-reducing slurries, while it persisted in autoclaved controls and in the nitrate-reducing slurries. Aquifer slurries incubated with either 2,4- or 2,6-diaminotoluene showed losses of these compounds relative to autoclaved controls under nitrate-reducing conditions but not under sulfate-reducing or methanogenic conditions. These latter compounds are important as reduced intermediates in the biodegradation of dinitrotoluenes and as industrial chemicals. In experiments to examine sorption, exposure to landfill sediment resulted in losses of approximately 15% of diaminotoluene isomers and 25% of aminodinitrotoluene isomers from initial solution concentrations within 24 h. Isotherms confirmed that the diaminotoluenes were least strongly sorbed and the amino-dinitrotoluenes most strongly sorbed to this sediment, while TNT sorption capacity was intermediate. In our studies, 2,4,6-triaminotoluene sorption capacity was indeterminate due to its chemical instability. Coupled with biodegradation information, isotherms help describe the likelihood of contaminant removal, persistence, and movement at impacted sites. Received 11 March 1996/ Accepted in revised form 24 July 1996     

Aerobic biotransformation of 2,4-dinitroanisole in soil and soil Bacillus sp.

2,4-Dinitroanisole (DNAN) is a low sensitive melt-cast chemical being tested by the Military Industry as a replacement for 2,4,6-trinitrotoluene (TNT) in explosive formulations. Little is known about the fate of DNAN and its transformation products in the natural environment. Here we report aerobic biotransformation of DNAN in artificially contaminated soil microcosms. DNAN was completely transformed in 8 days in soil slurries supplemented with carbon and nitrogen sources. DNAN was completely transformed in 34 days in slurries supplemented with carbons alone and persisted in unamended microcosms. A strain of Bacillus (named 13G) that transformed DNAN by co-metabolism was isolated from the soil. HPLC and LC–MS analyses of cell-free and resting cell assays of Bacillus 13G with DNAN showed the formation of 2-amino-4-nitroanisole as the major end-product via the intermediary formation of the arylnitroso (ArNO) and arylhydroxylamino (ArNHOH) derivatives, indicating regioselective reduction of the ortho-nitro group. A series of secondary reactions involving ArNO and ArNHOH gave the corresponding azoxy- and azo-dimers. Acetylated and demethylated products were identified. Overall, this paper provides the evidence of fast DNAN transformation by the indigenous microbial populations of an amended soil with no history of contamination with explosives and a first insight into the aerobic metabolism of DNAN by the soil isolate Bacillus 13G.     

Botanical composition, production and nutrient status of an originally Lolium perenne-dominant cut grass sward receiving long-term manure applications

Effects of long-term applications (50, 100 and 200 m³ ha^?1y^?1) of pig and cow slurries on yield, botanical composition and nutrient content of herbage of an original perennial ryegrass sward were assessed in a three-cut silage system and compared with unamended and fertilized controls in the 36th year of the experiment. Cow slurry at 50 m³ ha^?1 produced similar annual herbage DM yield to 200 kg ha^?1 fertilizer N in 2006, whereas about 100 m³ ha^?1 pig slurry were required to produce a similar amount of DM. The highest slurry application rate significantly influenced sward botanical composition without depressing DM yield. The principal invading species were creeping bent and meadow grasses (similar to findings at a previous assessment in 1981) except in the unamended control (which were common bent and Yorkshire fog). Perennial ryegrass remained a main species in plots receiving fertilizer (31 % annual DM yield) and low slurry rates (38 %) but declined to 3 % annual DM yield at the highest slurry rate where the ability of ryegrass to utilize slurry N and P may have been affected by chemically or physically induced deficiencies of other nutrients (e.g. Ca) or direct physical effects such as smothering.     

Recombinant protein expression of Moringa oleifera lectin in methylotrophic yeast as active coagulant for sustainable high turbid water treatment

The natural coagulant Moringa oleifera lectin (MoL) as cationic protein is a promising candidate in coagulation process of water treatment plant. Introducing the gene encoding MoL into a host, Pichia pastoris, to secrete soluble recombinant protein is assessed in this study. Initial screening using PCR confirmed the insertion of MoL gene, and SDS-PAGE analysis detected the MoL protein at 8 kDa. Cultured optimization showed the highest MoL protein at 520 mg/L was observed at 28 °C for 144 h of culturing by induction in 1% methanol. Approximately, 0.40 mg/mL of recombinant MoL protein showed 95 ± 2% turbidity removal of 1% kaolin suspension. In 0.1% kaolin suspension, the concentration of MoL at 10 μg/mL exhibits the highest turbidity reduction at 68 ± 1%. Thus, recombinant MoL protein from P. pastoris is an effective coagulant for water treatment.     

Kaolin potential for the integrated management of Aphis gossypii Glov. (Homoptera: Aphididae) on cotton

Kaolin-based particle film has been developed in the United States for use in agriculture as crop protectant. This work is aimed to determine the optimal kaolin concentration for use against Aphis gossypii, the most damaging sucking insect of cotton in Benin, West Africa. Following kaolin concentrations have been tested in four different experiments: 2%, 3%, 4%, 5%, 6% and 8%. The effect of kaolin is tested by recording the population dynamics of A. gossypii on cotton after spraying. Results showed that the solution containing 5% of kaolin has significantly reduced aphids' number. This concentration corresponds to a maximum of 18 kg of kaolin per hectare for the entire season when ultra low volume sprayer is used. Higher kaolin concentrations have left a large deposit of kaolin particle on cotton leaves thus handicapping chlorophyll synthesis and the proper growth and development of the plants. To obtain encouraging results, an adequate application method that provides a full and continuous coverage of the plants with kaolin particle film should be used. We suggest conducting trials on this product in practical cotton production conditions in West Africa to assess its potentiality as integrated pest management (IPM) component.     

Bacterial community dynamics in aerated cow manure slurry at different aeration intensities

Aims: This study aimed to characterize microbial community dynamics in aerated cow manure slurry at different aeration intensities. Methods and Results: Batch aerobic treatments were set up in 5‐l jar fermentor, each containing 3 l of manure slurry; the slurries were subjected to low, medium and high (50, 150 and 250 ml min^?1, respectively) aeration for 9 days. Microbial community composition was determined using terminal restriction fragment length polymorphism and a clone library targeting 16S rRNA genes. High and medium aeration accelerated organic carbon degradation in parallel with the degree of aeration intensity; however, 90% of the initial total organic carbon was retained during low‐aeration treatment. During the active stages of organic carbon decomposition, clones belonging to the class Bacilli accumulated. Moreover, Bacilli accumulation occurred earlier under high aeration than under medium aeration. Conclusions: Organic matter degradation was mainly governed by a common microbial assemblage consisting of many lineages belonging to the class Bacilli. The timing of community development differed depending on aeration intensity. Significance and Impact of the Study: This study reports on changes in several environmentally important parameters and the principal microbial assemblage during the pollution‐reducing phase of cattle manure aeration treatment.