Characterization of humic materials extracted from hazelnut husk and hazelnut husk amended soils

This study was carried out to determine effects of composted hazelnut husk (CHH) on some chemical properties of soil and soil humic acid (HA). Compost application increases organic matter (OM) content of the soil considerably, OM value of 3.18% became 3.89% in 3 years time interval. Before application of compost, the soil pH was found to be 5.37, while after compost application it became 5.61. FTIR characteristics of humic acid/humic acid-like materials extracted from the original hazelnut husk, composted hazelnut husk and composted hazelnut husk amended soil have been investigated. C and O content of humic acid-like/humic acid materials were in the range of 41.4–50.8% and 37.8–50.5%, respectively. The N content of the humic acid/humic acid-like materials are in the expected range for humic materials which is 2–6%. Comparison of FTIR spectra of hazelnut husk and composted hazelnut husk humic acid-like fractions shows that both exhibit similar but not identical series of IR bands indicating the presence of the same functional groups in both samples. The only difference in the spectra seemed to be a decrement in the peak intensities of composted sample compared to uncomposted one. The similar differentiation of the intensities of IR bands of compost applied soil sample has also been observed. The FTIR spectral results show that the characteristics of composted material tend to become similar to that of soil humic acids characteristics in time.     

Biochemical characterization of a novel dual-function arabinofuranosidase/xylosidase isolated from a compost starter mixture

The gene encoding a glycoside hydrolase family 43 enzyme termed deAX was isolated and subcloned from a culture seeded with a compost starter mixed bacterium population, expressed with a C-terminal His₆-tag, and purified to apparent homogeneity. deAX was monomeric in solution and had a broad pH maximum between pH 5.5 and pH 7. A twofold greater k _cat/K _m for the p-nitrophenyl derivative of α-l-arabinofuranose versus that for the isomeric substrate β-d-xylopyranose was due to an appreciably lower K _m for the arabinofuranosyl substrate. Substrate inhibition was observed for both 4-methylumbelliferryl arabinofuranoside and the xylopyranoside cogener. While no loss of activity was observed over 4 h at 40°C, the observed t _1/2 value rapidly decreased from 630 min at 49°C to 47 min at 53°C. The enzyme exhibited end-product inhibition, with a K _i for xylose of 145 mM, 18.5 mM for arabinose, and 750 mM for glucose. Regarding natural substrate specificity, deAX had arabinofuranosidase activity on sugar beet arabinan, 1,5-α-l-arabinobiose, and 1,5-α-l-arabinotriose, and wheat and rye arabinoxylan, while xylosidase activity was detected for the substrates xylobiose, xylotriose, xylotetraose, and arabinoxylan from beech and birch. Thus, deAX can be classified as a dual-function xylosidase/arabinofuranosidase with respect to both artificial and natural substrate specificity.     

Behaviour of the pathogen surrogates Listeria innocua and Clostridium sporogenes during production of parsley in fields fertilized with contaminated amendments

The survival and transfer of Listeria innocua and Clostridium sporogenes, used as surrogates of the food borne pathogens Listeria monocytogenes and Clostridium botulinum, were quantitatively assessed under field conditions. In the soil, spores of C. sporogenes declined by less than 0.7 log cycles within 16 months and were detected on parsley leaves throughout the experiment. In contrast, L. innocua in the soil declined by 7 log cycles in 90 days and was detected on leaves in low numbers (>0.04 MPN g(-1)) during the first 30 days. Rates of decline in soil were similar in the laboratory at 20 degrees C for two strains of L. innocua and L. monocytogenes ; and in the field for L. innocua over two different years. L. innocua survived better in winter, indicating an important influence of temperature. The major cause of transfer of L. innocua from soil to parsley leaves was splashing due to rain and irrigation. As few as 1 CFU g(-1) Listeria in soil led to contamination of parsley leaves. Internalisation of Listeria through parsley roots was not observed. Under the conditions of soil and climate studied, a delay of 90 days between application of potentially contaminated fertilizer and harvest should be sufficient to eliminate L. monocytogenes.     

Production and characterization of thermostable cellulases from Streptomyces transformant T3-1

A total of 26 thermophilic isolates, selected from a compost of agricultural waste, which was mostly composed of vegetable, corncob and rice straw, were cultivated at 50 °C for further studies of thermostable cellulase production. The thermostable cellulase gene from the chromosomal DNA of actinomycetes isolate no. 10 was shotgun-cloned and transformed into Streptomyces sp. IAF 10-164. A transformant, T3-1, was found to be a good strain for the production of thermostable cellulases. Cultivation of T3-1 in modified Mandels–Reese broth containing 1% carboxymethylcellulose (CMC)-sodium salt and the optimal condition for microbial growth were studied. Batch cultivation in a flask revealed that CMCase and Avicelase production reached the maximum between the third to fifth day, whereas maximum -glucosidase production occurred on the ninth day. Microbial biomass increased from the first day to the fifth day and then decreased. The crude enzyme had the highest activity at 50 °C and at pH 6.5. The enzyme was shown to be a thermostable cellulase whose activities were stable at 50 °C for more than 7 days.     

Acidic and alkaline bottom ash and composted manure blends as a soil amendment

Potential water quality impacts associated with using bottom ash (BA) and composted dairy manure (CM) as a soil amendment were evaluated in this study. Two column studies were conducted to evaluate three blends of acidic BA and CM (BA:CM, v/v) namely, B1_ac (95:5), B2_ac (90:10), and B3_ac (80:20) and three blends of alkaline BA and CM (BA:CM, v/v), namely, B1_al (95:5), B2_al (90:10), and B3_al (80:20) under constant head water table conditions. Samples from standing water (top) and leachate (bottom) were collected at weekly intervals until day 49 to evaluate the effects of different blend ratios and elapsed time on standing water and leachate chemical and physical properties. A higher CM content in both acidic and alkaline blends resulted in higher leachate concentrations for solids and nutrients tested in this study. Alkaline blends had higher standing water and leachate nutrients concentration compared to acidic blends. After day 28, standing water total dissolved solids (TDS) concentrations for all acidic blends was below the USEPA drinking water standard however, TDS value for alkaline blend was always below the standard. Similar trends were also observed for NO₃–N and phosphorus (P) concentrations for both blends. Based on these findings, it was concluded that acidic and alkaline blends B1_ac, B1_al, B2_ac and B2_al may be considered as a soil amendment material.     

Mushroom worker's lung: Serologic reactions to thermophilic actinomycetes present in the air of compost tunnels

Vast numbers of spores of the thermophilic actinomycetesExcellospora flexuosa,Thermomonospora alba,T. curvata andT. fusca were collected from the air in fermentation tunnels during the spawning of mushroom compost, i.e. over 10⁹ CFU m^–3 of air. Five different genera of fungi, namely,Aspergillus,Aureobasidium,Cladosporium,Penicillium andScytalidium, were found at only 10³ CFU m^–3 of air.Agaricus bisporus, used for spawning, was absent. Sera of 10 mushroom growers affected by Mushroom Worker's Lung (MWL) were tested by a qualitative dot-ELISA for antibodies against the spores of these micro-organisms. All 10 were positive for one or more of the actinomycetesE. flexuosa,T. alba,T. curvata andT. fusca. No antibodies were found againstStreptomyces thermovulgaris,Thermoactinomyces vulgaris andT. sacchari nor against the fungiAspergillus fumigatus,Penicillium brevicompactum,P. chrysogenum,Scytalidium thermophilum andTrichoderma viride. Sera of 11 of 14 workers engaged in routine spawning of compost in tunnels reacted positively with 1 or more of the actinomycetes. Their¹⁰log serum titres increased with the duration of employment to an upper limit of 2.5. The sera of 19 non-exposed individuals were negative. Because high numbers of spores ofE. flexuosa,T. alba,T. curvata andT. fusca were present in the air that was used for successful inhalation provocation of mushroom workers with MWL and because of the elevated serum titres of these workers, we presume these organisms to contribute in the occurrence of MWL.     

The fate of ‘biodegradable’ plastics in municipal leaf compost

Summary Blends of starch with polypropylene, starch with polyethylene, polycaprolactone with polyethylene, and a copolymer of -hydroxybutyrate and -hydroxyvalerate (PHB/V) were exposed to degrading leaves in a municipal leaf composting operation. Every month for 6 months, duplicate samples were analyzed for changes in weight and tensile properties, and many of these samples were further analyzed for changes in molecular weight and surface morphology. All results were compared to controls which were incubated for 6 months in moist, sterile leaves at a leaf compost temperature. Very little change was noted for any of the polyolefin blends over the 6-month period. In contrast, PHB/V samples showed massive deterioration with substantial weight loss. Although there was a decrease in molecular weight and a loss of tensile properties in leaf-exposed PHB/V films, the sterile control films also showed similar changes, but without weight loss. Of the microbial isolates from film surfaces, only fungi possessed PHB/V depolymerase activity.     

MonitoringAspergillus fumigatus aerosols from a composting facility

The large, outdoor Islip Yard Waste Composting Facility on Long Island, New York was investigated as a source of airborne fungus spores. The Burkard-Hirst volumetric spore trap was used for the first extensive sampling of small mold spores for this application. Samplers were operated continuously from 21 August to 30 November 1992 in the facility and in a suburban community about 540 m from the facility. A control site approximately 10 000 m from the facility was also sampled to establish background levels of fungus spores. The facility site had higher average readings ofAspergillus fumigatus spores than did the community and both were higher than the control.A. fumigatus was the only fungus among 30 categories tracked that differed significantly between the facility and control sites. It was also isolated repeatedly from the compost. Higher average levels ofA. fumigatus were measured in the community when winds blew from the facility, and also during times when the compost was moved or mixed at the facility. No correlation was found between wind direction or work times andA. fumigatus conidia at the control site. The study shows that this compost facility can produce a measurable increase in the number of airborneA. fumigatus conidia both at the edge of the facility and at 540 m downwind. It also demonstrates that the Burkard spore trap can be used for monitoring small, airborne mold spores, but it is a difficult and labor intensive task.     

Effect of fungal consortium and animal manure amendments on phosphorus fractions of paddy-straw compost

The study was conducted to reveal the type of phosphorus (P) fractions present in mature compost prepared by co-composting paddy straw (P.S) with cattle manure (CM), farm yard manure (FYM) and poultry manure (PM), each added separately as nitrogen (N) and P source. A consortium of phytate mineralizing fungi developed by including Aspergillus niger ITCC 6719, Aspergillus flavus ITCC 6720 and Trichoderma harzianum ITCC 6721 was applied for recovery of P from plant and animal residues. Chemical evaluation of compost after 4 months of aerobic decomposition revealed that inoculation improved the sodium bicarbonate-extractable P content of CM and FYM supplemented P.S compost by 32.3% and 23.5% respectively compared with their respective un-inoculated control. However, the peak values for water soluble-P fractions were recorded in CM–straw compost followed by PM–straw compost. Fungal inoculation also improved the agronomic quality of PM–straw compost as the latter had the highest total P content and lowest C:N and E4/E6 ratio of 18:1 and 5.36:1 respectively. The recovery of organic P from agricultural residue has the potential to reduce the application of synthetic P fertilizer. P-enriched organic manure can offer potential environment and economic benefits to farmers under sustainable agriculture.