Surface Microorganisms Research Articles

Geoquímica das águas subterrâneas de um aterro de resíduos sólidos urbanos em Araras, SP

A contaminated area associated with a residential unlined landfill, located in Araras, was investigated. The aim of this work was to develop a hydrogeological and geochemical conceptual model in order to identify the redox zones related to the landfill and to explain the main processes resulting from the impact of leachates on the local groundwaters and soil. The work consisted of a surface geological mapping, geophysical survey with electric tomography, logging of subsoil boreholes, an installation of monitoring wells and soil, gas, leachate and groundwater samples analyses. The results show that the Araras landfill is in the methanogenic phase and promotes alterations in local groundwater quality. The main parameters of environmental interest identified in the leachate were total dissolved solids, biochemical oxygen demand, ammonium, methane, Na, Cl, Fe, Mn, Ba, B, Co and Cd. According to criteria specifically developed for this landfill, the following redox zones were identified in the groundwater: (i) aerobic, located upgradient from the landfill; (ii) methanogenic, downgradient from the landfill; (iii) iron and/or manganese reduction, located between the methanogenic zone and the Araras river. Bypassing the iron and/or manganese redox zone, the existence of a denitrification zone was inferred. Besides the redox reactions in these zones, other processes that mitigate the impact of leachate into groundwater were also discovered: dilution, degradation by the action of surface microorganisms, dispersion, ionic exchange, formation of organic and inorganic complexes, dissolution and precipitation.

The Antimicrobial Efficacy of Copper Alloy Furnishing in the Clinical Environment: A Crossover Study

To determine whether copper incorporated into hospital ward furnishings and equipment can reduce their surface microbial load. A crossover study. Acute care medical ward with 19 beds at a large university hospital. Fourteen types of frequent-touch items made of copper alloy were installed in various locations on an acute care medical ward. These included door handles and push plates, toilet seats and flush handles, grab rails, light switches and pull cord toggles, sockets, overbed tables, dressing trolleys, commodes, taps, and sink fittings. Their surfaces and those of equivalent standard items on the same ward were sampled once weekly for 24 weeks. The copper and standard items were switched over after 12 weeks of sampling to reduce bias in usage patterns. The total aerobic microbial counts and the presence of indicator microorganisms were determined. Eight of the 14 copper item types had microbial counts on their surfaces that were significantly lower than counts on standard materials. The other 6 copper item types had reduced microbial numbers on their surfaces, compared with microbial counts on standard items, but the reduction did not reach statistical significance. Indicator microorganisms were recovered from both types of surfaces; however, significantly fewer copper surfaces were contaminated with vancomycin-resistant enterococci, methicillin-susceptible Staphylococcus aureus, and coliforms, compared with standard surfaces. Copper alloys (greater than or equal to 58% copper), when incorporated into various hospital furnishings and fittings, reduce the surface microorganisms. The use of copper in combination with optimal infection-prevention strategies may therefore further reduce the risk that patients will acquire infection in healthcare environments.

The application of various disinfectants by fogging for decreasing postharvest diseases of strawberry

In this study, chlorine dioxide (ClO 2), sodium hypochlorite (NaClO), hydrogen peroxide (H 2O 2), citric acid (C 6H 8O 7) and ethanol (EtOH) were applied to strawberry fruit using a fogger with an ultrasonic aerosol generator that can produce spheres at 1.2 μm in diameter. Fruit were treated at room temperature for 30 min while with the fogger operating and for an additional 30 min in the fog consisting of disinfectants. Treated fruit were stored at 1 °C for 5 days and an additional 2 days at 20 °C. The percentage of infected fruit and microorganism populations on the surface of the fruit and in the storage air were evaluated to determine the efficacy of treatments. Chlorine dioxide, hydrogen peroxide, sodium hypochlorite, citric acid and ethanol significantly reduced the percentage of infected fruit. The percentage of decay was reduced to 14.5% from 83.2% by the hydrogen peroxide treatment at 2000 μL L −1 and to 32.5% by sodium hypochlorite at 2000 μL L −1 in the first experiment. In addition, all chemicals significantly reduced the total number of microorganisms on the fruit surface and in the storage atmosphere. Hydrogen peroxide at 2000 μL L −1 achieved approximately a 2 log reduction on the surface microorganism population in the first experiment. The study showed that application of disinfectants by fogging was effective in reducing postharvest diseases of strawberry.

Effect of photocatalytic and hydrophobic coatings on brewery surface microorganisms.

The aim of this study was to determine whether process hygiene in the beverage industry could be improved by applying new coating techniques to process surfaces. Photocatalytic titanium dioxide (TiO(2)) and hydrophobic coatings applied to stainless steel with or without added antimicrobial compounds were studied in laboratory attachment tests and in a 15-month process study. No clear reductions in numbers of attached microbes were obtained with photocatalytic coatings, except for coatings to which silver had been added. These TiO(2)+Ag coatings reduced microbial coverage in laboratory studies and in some process samples. Hydrophobic coatings reduced the area coverage of microorganisms in 4-h laboratory studies but did not affect colony counts in laboratory or process studies. The surfaces had changed from hydrophobic into hydrophilic during the process study. The coatings did not mechanically fully withstand process conditions; part of the hydrophobic coatings had peeled off, most of the precipitated Ag had dissolved, and some of the TiO(2) coatings were damaged. In conclusion, functional coatings have potential for reducing microbial loads on beverage industry surfaces, but these coatings need further development.

Comparison of the Surface and Core Bacteria in Tonsillar and Adenoid Tissue With Beta-Lactamase Production

Adenoidectomy and tonsillectomy, indicated for children with recurrent or persistent symptoms of infection or hypertrophy, are among the most frequent operations performed in children. This study was carried out for investigating the microbial flora of the tonsils and adenoids regarding to core and surface microorganisms and also pathogen microrganisms' beta-lactamase production rate. Cultures were taken from the core and surface of tonsils and adenoids of the 91 patients at the time of the surgery for tonsillectomy and adenoidectomy. Aerobic and anaerobic cultures were inoculated and identified. Beta-lactamase production was detected also. The most frequently isolated aerobic microorganisms were Streptococcus viridans and Neisseria spp. The number of the microorganisms isolated from the tonsil core compared to the surface of the tonsils was found statistically insignificant (P>0.05). The number of the adenoid surface aerobic microorganisms was found higher from the adenoid core (P<0.05). The amount of adenoid and tonsil core anaerobic microorganisms were alike. The patients' preoperative antibiotherapy whether using beta-lactam or beta-lactamase resistant were compared for beta-lactamase producing bacteria production and the number of beta-lactamase producing bacteria were found statistically insignificant (P>0.05). The togetherness of Staphylococcus aureus and other beta-lactamase producing bacteria was found statistically significant (P<0.05). This study demonstrates that there is polymicrobial aerobic-anaerobic flora in both adenoids and tonsils. There was a close relationship between the bacteriology of the tonsil and adenoid flora. Staphylococcus aureus and and other beta-lactamase producing bacteria may be responsible for treatment failures in patients with tonsillitis.

Assessing the efficacy of different microfibre cloths at removing surface micro-organisms associated with healthcare-associated infections

This study investigated the ability of 10 different microfibre cloths to remove microbial contamination from three surfaces commonly found in hospital settings (stainless steel, furniture laminate and ceramic tile), under controlled laboratory conditions. Tests were conducted using organisms known to cause healthcare-associated infections, i.e. meticillin-resistant Staphylococcus aureus (MRSA), Clostridium difficile (in spore form) and Escherichia coli. For all the cloths tested, there was significant statistical evidence to suggest a difference in cleaning performance between them on first and single use (P<0.001). However, the overall performance of the nine re-useable cloths did not differ in practice with differences in log₁₀ reductions of <1. The performance of the disposable microfibre cloth was notably worse. The performance of all cloths decreased with repeated use on a succession of contaminated surfaces. After repeated washing, re-usable cloth performance improved at 75 washes, and reduced after 150 washes, although, in most instances, performance after 150 washes was better than at first wash. For all cloths, price was not an indication of performance. Based on these laboratory findings, it is concluded that use of the microfibre cloths investigated is an effective way to reduce the levels of MRSA, E. coli and C. difficile (in spore form) on a range of surfaces found in the clinical environment and could therefore be of benefit to these environments.

Outbreaks where food workers have been implicated in the spread of foodborne disease. Part 9. Washing and drying of hands to reduce microbial contamination.

During various daily activities at home and work, hands quickly become contaminated. Some activities increase the risk of finger contamination by pathogens more than others, such as the use of toilet paper to clean up following a diarrheal episode, changing the diaper of a sick infant, blowing a nose, or touching raw food materials. Many foodborne outbreak investigation reports have identified the hands of food workers as the source of pathogens in the implicated food. The most convenient and efficient way of removing pathogens from hands is through hand washing. Important components of hand washing are potable water for rinsing and soaps to loosen microbes from the skin. Hand washing should occur after any activity that soils hands and certainly before preparing, serving, or eating food. Antimicrobial soaps are marginally more effective than plain soaps, but constant use results in a buildup of the antimicrobial compound on the skin. The time taken to wash hands and the degree of friction generated during lathering are more important than water temperature for removing soil and microorganisms. However, excessive washing and scrubbing can cause skin damage and infections. Drying hands with a towel removes pathogens first by friction during rubbing with the drying material and then by wicking away the moisture into that material. Paper rather than cloth towels should be encouraged, although single-use cloth towels are present in the washrooms of higher class hotels and restaurants. Warm air dryers remove moisture and any surface microorganisms loosened by washing from hands by evaporation while the hands are rubbed together vigorously; however, these dryers take too long for efficient use. The newer dryers with high-speed air blades can achieve dryness in 10 to 15 s without hand rubbing.

The cylinder agar slice technique for isolation of surface microorganisms.

Summary A technique for bacteriological surface examination using “cylinder slice agar” is described. The method is practical and simple. It is possible in any small laboratory to prepare cylinder agar from any type of agar, and to transport the cylinders readily to distant centres of sampling. Zusammenfassung Es ist eine Technik zur Bakteriologischen Oberflächen-Untersuchung mit „Zylinder-Scheiben-Agar” beschrieben. Die Methode ist in der Praxis leicht ausführbar. Der „Zylinder Agar” kann in jedem kleinen Labor hergestellt werden und ist leicht zu der Arbeitsstelle transportierbar, wenn auch vom Labor entfernt.

Microbiological assessment of food crops irrigated with domestic greywater

Two of the challenges facing Africa in the 21stcentury are effective use of restricted water resources and ensuring food security. The eThekwini Municipality is not exempt from these challenges and is investigating ways in which they can be addressed in the local context. One of the aims of national government has been to ensure the supply of clean drinking water and suitable sanitation to every household. As part of its efforts in this regard, eThekwini Municipality has introduced a multi-tiered water supply programme ranging from full-pressure water systems and flush toilets to stand pipes and dry toilets. In the dry sanitation systems, there is no real provision for the disposal of domestic greywater and, bearing in mind that South Africa is a water scarce country, the municipality is investigating ways of using this water as a resource rather than viewing it as a waste. A preliminary trial was set up in 2003 using this water to irrigate vegetables to be used for home consumption. The microbiological safety of this practice needed to be examined to ensure that it would indeed help to uplift communities by the provision of healthy food as well as provide an ecologically sound use and reuse of available water. The initial proposal was to investigate total coliforms, E. coli and Enterococcus as the normal faecal indicators for health purposes as well as Staphylococcus as a human skin surface micro-organism and coliphage as a viral indicator. The first controlled field trial was put in at the test site at the University of KwaZulu-Natal in 2005 using several crop types and three irrigation regimes. The vegetable samples were examined both internally and externally for the selected micro-organisms. It was found that very few E. coli were detected and in later crops the micro-organism list was expanded and further identification of the total coliform organisms detected is being addressed. This paper presents the results from the analyses to date.

EFFECTS OF STERILIZATION BY GAMMA RADIATION OF EDIBLE STORED VIGNA MUNGO L. AND TRITICUM AESTIVUM L. SEED INFESTED WITH SURFACE MICROFLORA IN INDIA

ABSTRACT An effective 60Co gamma irradiation method for the removal of contaminating surface microorganisms (fungi) of mung (Vigna mungo L.) and wheat (Triticum aestivum L.) stored seeds, without the loss of germination capacity and minimum loss of nutritional values, are described. Significant depletion of surface fungal population on wheat (96%) and mung (94%) was noticed within 2 kGy, while complete inhibition of surface fungal population was observed at 4.2 kGy. Although the irradiation did not significantly alter the germination potential of the treated grains, it reflected delay in germination as a function of absorbed dose. The seed membrane permeability and nutritional values like carbohydrate and protein content of the radiation‐exposed seed were significantly altered. The radiosensitivity of wheat was found more than that of the mung. It was also observed that the germinating potential of the treated seeds did not alter significantly. However, membrane permeability of seeds was altered as a result of gamma irradiation. Precisely, the investigation reflected that the dose range from 1 to 2 kGy was most effective for seed sterilization, keeping their viability and minimum loss of nutritional value like protein and carbohydrate intact.PRACTICAL APPLICATIONSThere are many reports on radiation sterilization of stored seeds without any consideration of the nutritional quality of the seeds, which is very important for quality control. We should look upon change of quality of seed during seed sterilization. We need to protect/or estimate minimal loss of the nutritional value of stored seed by loss and benefit assessment. The significance and originality of this manuscript is that we try to look for an effective 60Co gamma irradiation method for the removal of contaminating surface microorganisms (fungi) of mung (Vigna mungo L.) and wheat (Triticum aestivum L.) stored seeds, without the loss of germination capacity and minimum loss of nutritional values. The study was concentrated on germination pattern, protein, carbohydrate and intensity of seed membrane damage during radiation processing. Also, our present work emphasized on radiosensitivity of different seed‐borne fungi that frequently infected seed grain during storage. This study may help to sterilize the stored seed with consideration of nutritional value.

UV treatment of microorganisms on artificially-contaminated surfaces using excimer and microwave UV lamps

An XeBr excilamp having a peak emission at 283 nm, and microwave UV lamps with peak emissions at 253.7 nm that also generate ozone, have been tested for ability to eradicate high populations of microbial vegetative cells and spores (of bacteria and fungi) artificially added to filter surfaces. The study examined the energy required to completely eradicate large populations on filter surfaces. It was found that both the excilamp and microwave UV lamps were effective at killing large populations on surfaces with killing efficiency dependant on the type of organism, and, whether present in its vegetative or spore forms. The main killing factor is UV radiation following short treatment times. It is considered that for longer irradiation periods that are required to facilitate complete destruction of surface microorganisms, ozone and other oxidising species produced by microwave UV lamps would act to enhance microbial destruction.

Properties and antimicrobial activity of the smear surface cheese coryneform bacterium Brevibacterium linens

Surface microorganisms contribute to the ripening of some low-moisture cheese varieties and the composition of the surface microflora is dynamic. Brevibacterium linens is an important surface microorganism that is present in the smear of surface-ripened cheeses and is commonly regarded as the organism primarily responsible for the characteristic taste, aroma, and color of surface cheese. The enzymology and biochemical characteristics of B. linens influence the ripening and final characteristics of smear surface-ripened cheeses. Proteolytic, peptidolytic, esterolytic, and lipolytic activities are of particular importance in the ripening process. Because of its putative importance to the ripening in smear-ripened cheeses, B. linens is the best studied component of the microflora, although in comparision with other dairy-related microorganisms, it is poorly characterized. B. linens produces antimicrobial substances that inhibit the growth of many food poisoning bacteria as well as several yeast and moulds. Some inhibitory substances produced by this species were identified as bacteriocins. Bacteriocins could appear as potential agents to be applied in food conservation systems in order to provide microbiologically stable foods. This article describes the properties of B. linens and discusses about the potential of this species to produce bacteriocins and other antimicrobial substances, which are important for production of high quality cheese.

Intestinal Spirochetosis: A Cause of Symptoms Resembling Irritable Bowel Syndrome

Purpose: Intestinal spirochetosis (IS) is an uncommon, but treatable cause of gastrointestinal symptoms that often resemble irritable bowel syndrome (IBS). We report a case of IS in a homosexual male presenting with chronic watery diarrhea. A 25 year old homosexual male of Asian origin presented with an eight-year history of watery diarrhea. He denied rectal bleeding, abdominal pain and weight loss. Physical examination was unremarkable. Biochemical and hematological parameters were normal. Stool examination did not reveal conventional pathogens. No gross abnormalities were noted on colonoscopy. Hematoxylin and eosin (H &E) stained slides of colonic mucosal biopsy specimens revealed a focally prominent surface epithelial brush border with basophilic microorganisms adherent to the epithelial surface, suggestive of IS. The diagnosis was confirmed with Steiner silver stain, which highlighted surface microorganisms. A seven day course of oral metronidazole was offered as therapy for IS. IS is an uncommon clinical entity in North America, with an estimated prevalence of 2.5% to 6.5%. Higher prevalence rates (11.4 to 64.3%) have been observed in developing countries, in homosexuals and HIV-infected individuals. Colonization of the colonic mucosa by various species of spirochetes, including Brachyspira aalborgi and Serpulina pilosicoli, is almost an incidental finding in an asymptomatic patient. Spirochetal invasion of the colonic epithelium, resulting in epithelial changes and inflammatory infiltrate in the lamina propria, is associated with symptoms. However, in homosexual men, regardless of HIV status, symptoms may be present in the absence of epithelial invasion. Persistent diarrhea, abdominal pain or constipation occur either alone or in combination, often resembling IBS. The diagnosis of IS is suspected on H & E staining of colonic mucosal specimens, and confirmed by silver stains, immunohistochemistry or electron microscopy. Due to patchy distribution of spirochetes, multiple site colonic biopsies are recommended for a definitive diagnosis. Of the several regimens proposed, metronidazole seems to be superior in eradicating spirochetes from the intestine. In conclusion, IS should be considered as a differential diagnosis in patients with IBS-like symptoms, with an otherwise grossly normal-appearing colonic mucosa. Metronidazole should be offered as first-line therapy for the treatment of IS.

Comparison of surface microfouling and bacterial attachment on the egg capsules of two molluscan species representing Cephalopoda and Neogastropoda

AME Aquatic Microbial Ecology Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials AME 47:275-287 (2007) - doi:10.3354/ame047275 Comparison of surface microfouling and bacterial attachment on the egg capsules of two molluscan species representing Cephalopoda and Neogastropoda Norman S. H. Lim, Kim J. Everuss, Amanda E. Goodman, Kirsten Benkendorff* School of Biological Sciences, Flinders University of South Australia, GPO Box 2100, Adelaide, South Australia 5001, Australia *Corresponding author.Email: kirsten.benkendorff@flinders.edu.au ABSTRACT: Many organisms naturally defend themselves against microbial attachment and biofouling in the marine environment. In this study, we investigated microbial fouling on 2 molluscan egg capsules using scanning electron microscopy (SEM), two-photon laser scanning microscopy (TPLSM) with bacterial viability staining and bacterial attachment experiments with the biofilm-forming Pseudoalteromonas sp. S91 in flow chambers. Results indicated that early stage egg capsules of Dicathais orbita (Neogastropoda) are relatively free of surface microorganisms. Egg capsules during the trocophore stage had a regularly ridged microtexture, but as capsules matured, shedding of the outer wall was observed, followed by the extrusion of unidentified droplets, which then accumulated on the capsule surface in association with bacteria. By comparison, the egg capsules of Sepioteuthis australis (Cephalopoda) were found to have an irregular surface with many hills and valleys that accommodate colonization by a variety of microorganisms. At the later stages of development these squid egg capsules become heavily colonized by algal spores. Cross sections of egg capsules revealed that S. australis capsule walls were about 12 times thicker than D. orbita egg capsules. Staining the egg capsules with BacLight™ also revealed a significantly thicker biofilm, with more live and dead bacteria on S. australis capsules than on those of D. orbita (p < 0.05). Flow chamber experiments indicated that the surface of S. australis capsules provided a suitable substrate for colonization by Pseudoalteromonas sp. S91, whereas colonization was significantly less on D. orbita egg capsules after 24 and 72 h (p < 0.01). These experiments indicated that D. orbita egg capsules are better defended against fouling microbes than are the eggs of S. australis. D. orbita appears to use a combination of physical, mechanical and possibly chemical defense mechanisms to reduce fouling on their egg capsules. KEY WORDS: Biofilm · Egg capsules · Mollusc · Scanning electron microscopy · Two-photon laser scanning microscopy · Bacterial attachment Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in AME Vol. 47, No. 3. Online publication date: May 30, 2007 Print ISSN: 0948-3055; Online ISSN: 1616-1564 Copyright © 2007 Inter-Research.

Biosolids Impact Soil Phosphorus Accountability, Fractionation, and Potential Environmental Risk

Biosolids land application rates are typically based on crop N requirements but can lead to soil P accumulation. The Littleton/Englewood, Colorado, wastewater treatment facility has supported biosolids beneficial-use on a dryland wheat-fallow agroecosystem site since 1982, with observable soil P concentration increases as biyearly repeated biosolids applications increased from 0, 6.7, 13, 27, to 40 Mg ha(-1). The final study year was 2003, after which P accountability, fractionation, and potential environmental risk were assessed. Between 93 and 128% of biosolids-P added was accounted for when considering conventional tillage soil displacement, grain removal, and soil adsorption. The Fe-P fraction dominated all soil surface P fractions, likely due to an increase in amorphous Fe-oxide because Fe2(SO4)3 was added at the wastewater treatment facility inflow for digester H2S reduction. The Ca-P phase dominated all soil subsurface P fractions due to calcareous soil conditions. A combination of conventional tillage, drought from 1999 to 2003, and repeated and increasing biosolids application rates may have forced soil surface microorganism dormancy, reduction, or mortality; thus, biomass P reduction was evident. Subsurface biomass P was greater than surface biomass, possibly due to protection against environmental and anthropogenic variables or to increased dissolved organic carbon inputs. Even given years of biosolids application, the soil surface had the ability to sorb additional P as determined by shaking the soil in an excessive P solution. Biosolids-application regulations based on the Colorado Phosphorus Index would not impede current site practices. Proper monitoring, management, and addition of other best management practices are needed for continued assurance that P movement off-site does not become a major issue.

In vitro effects of metals and pesticides on dehydrogenase activity in microbial community of cowpea (Vigna unguiculata) rhizoplane

Effects of heavy metals and pesticides on cowpea (Vigna unquiculata) rhizoplane microbial community were assessed in vitro via dehydrogenase activity. The microbial community was exposed to various concentrations of heavy metals and pesticides in a nutrient broth-glucose-2,3,5-triphenyl chloride (TTC) medium. At 0.2 mM, iron and cadmium stimulated the dehydrogenase activity of the microbial community. For all the metal ions, there was progressive inhibition with each successive increase in the concentration of metal ion, reaching near 100% at 0.6, 0.8, 1.2, 0.12 and 12 mM for cobalt, cadmium, iron, mercury and nickel, respectively. Between 0.2 and 0.4 mM, zinc sharply inhibited dehydrogenase activity and at concentration above 0.4 mm, inhibition of dehydrogenase activity became less pronounced. The order of toxicity is Hg2+ > Co2+ > Cd2+ > Zn2+ > Fe2+ > Ni2+. The herbicides Cotrazine (Atrazine 80W) and Northrin®10EC stimulated dehydrogenase activity of the microbial community at 0.2% and inhibited it at higher concentrations. The median inhibitory concentrations (IC50s) of Cotrazine (Atrazine 80W) and Northrin®10EC were 0.552 ± 0.028 and 0.593 ±0.051%, respectively. The dehydrogenase activity varied significantly (p < 0.05) with the type and concentrations of metals or pesticides. The result indicates that the heavy metals and pesticides are potentially toxic to V. unquiculata root surface microorganisms. In soil, this toxicity may affect nitrogen fixation processes and by extrapolation affect crop yield. Key words: Dehydrogenase activity, rhizosplane bacteria, atrazine, cypermethrin, heavy metals, cowpea.

In vitro effects of metals and pesticides on dehydrogenase activity in microbial community of cowpea (Vigna unguiculata) rhizoplane

Effects of heavy metals and pesticides on cowpea (Vigna unquiculata) rhizoplane microbial community were assessed in vitro via dehydrogenase activity. The microbial community was exposed to various concentrations of heavy metals and pesticides in a nutrient broth-glucose-2,3,5-triphenyl chloride (TTC) medium. At 0.2 mM, iron and cadmium stimulated the dehydrogenase activity of the microbial community. For all the metal ions, there was progressive inhibition with each successive increase in the concentration of metal ion, reaching near 100% at 0.6, 0.8, 1.2, 0.12 and 12 mM for cobalt, cadmium, iron, mercury and nickel, respectively. Between 0.2 and 0.4 mM, zinc sharply inhibited dehydrogenase activity and at concentration above 0.4 mm, inhibition of dehydrogenase activity became less pronounced. The order of toxicity is Hg2+ > Co2+ > Cd2+ > Zn2+ > Fe2+ > Ni2+. The herbicides Cotrazine (Atrazine 80W) and Northrin®10EC stimulated dehydrogenase activity of the microbial community at 0.2% and inhibited it at higher concentrations. The median inhibitory concentrations (IC50s) of Cotrazine (Atrazine 80W) and Northrin®10EC were 0.552 ± 0.028 and 0.593 ± 0.051%, respectively. The dehydrogenase activity varied significantly (p pesticides. The result indicates that the heavy metals and pesticides are potentially toxic to V. unquiculata root surface microorganisms. In soil, this toxicity may affect nitrogen fixation processes and by extrapolation affect crop yield.

Agrichemical impact on growth and survival of non-target apple phyllosphere microorganisms

The impact of conventional agrichemicals commonly used in New Zealand apple production on non-target, culturable phyllosphere microbial populations was studied in the laboratory (agar, leaf, and seedling assays) and field (apple orchard). Morphologically distinct bacteria (three), yeasts (five), and filamentous microfungi (two) were used as indicator species. The agar assay showed that agrichemical toxicity to microorganisms was dependent on product type, product rate, and organism studied. While the fungicides metiram and captan stopped or severely reduced growth of nearly all microorganisms studied, the insecticides tebufenozide and lufenuron and the fungicide nitrothal-isopropyl showed the least amount of microbial toxicity, each affecting 2 of the 10 indicator organisms studied. In the leaf assay a single agrichemical application at field rate either reduced or increased microbial population counts, again depending on product and microorganism. Repeated agrichemical applications, however, reduced microbial population numbers from 10- to 10,000-fold in planta. Further field research validated these findings, although differences in microbial numbers before and after agrichemical applications were less dramatic. In the orchard, total organism numbers recovered within 2-6 days, but species richness (sum of recognizable taxonomic units) declined. Agrichemicals clearly affected non-target, culturable surface microorganisms. The importance of diversity and stability of microbial populations for disease control still needs to be established.

Evidence of Protocarnivory in Triggerplants (Stylidium spp.; Stylidiaceae)

Australian triggerplants (Stylidium spp.; Stylidiaceae) trap small insects using mucilage-secreting glandular hairs held at various points on their inflorescence stems and flower parts. Triggerplants are generally found in habitats also containing genera of plants already accepted as carnivorous, two of which (Drosera, Byblis) use the same basic mechanism as Stylidium to trap their prey. In the herbarium, sheets of triggerplants and of accepted groups of carnivorous plants held similar numbers of trapped insects, and in the field, trapping of small prey per unit of glandular surface area was the same at a given site for triggerplants and for nearby carnivorous plants at three sites in northern Australia. Even more important, protease activity was produced by glandular regions of both triggerplants and Drosera after induction with yeast extract. A panel of negative and positive controls, including use 1) of plants grown in tissue culture, which therefore lack surface microorganisms, and 2) of protease inhibitors, shows that this activity 1) is generated by the glandular regions of the triggerplant itself, not by organisms that might reside on the surface of the plants, and 2) is due to proteases. All of this evidence taken together provides strong evidence of protocarnivory in Stylidium, something not previously suggested in the scientific literature, though the insect trapping has been noted informally. Experiments remain to be done to determine nutrient uptake, so triggerplants may well be fully carnivorous.

Techniques for Contamination Assessment During Drilling for Terrestrial Subsurface Sediments

Details about the procedures for drilling a ca. 150 m long drill core in a terrestrial setting under contamination controlled conditions are presented. Different to previous studies we only used commercially available drilling equipment to reduce the cost of operation significantly. The goals were (1) to minimize, (2) to monitor and, if possible, to quantify the contamination of the recovered sediments, and (3) to identify the different sources of contamination. Both the potential contamination of the sample material by surface microorganisms and non-indigenous material was assessed. To estimate the infiltration of drill mud into the core, fluorescent microspheres, having about half the size as microorganisms, were added to the mud. The drilling technique used was mud rotary drilling. With the exception of the very beginning of the drilling operations, the drill mud was devoid of any allochthonous hydrocarbons potentially derived from the drilling equipment or drill additives, and its biomarker composition reflected the varying organo-facies that were penetrated. Due to the lack of allochthonous hydrocarbons in the drill mud, its infiltration into the sediment cannot be traced by organic geochemical biomarker analysis. Microspheres proved to be a sensitive tool for the assessment of infiltration of drill mud into the core. The concentration of microspheres in the drill mud decreased continuously during the drilling, most probably caused by seepage of mud through leaks and attachment of spheres to the surface scum in the mud pit. Microscopic enumeration of the microspheres showed great variability in the depth of penetration of mud into the core, apparently unaffected of lithology. The sampling of the core material in the laboratory was carried out inside an anaerobic chamber. Several techniques for subsampling were used, according to sediment properties. The overall results indicate that, if strict contamination control protocols are employed, it is possible to recover uncontaminated samples at reasonable cost with commercially available drilling equipment.