Diversity and frequency of Nocardia spp. in the soil of Isfahan province,Iran

Objective

To isolate and identify Nocardia spp. from soil in different regions of Isfahan province in the center of Iran.

Methods

This study was conducted in 32 districts (16 cities and 16 villages) in Isfahan province during two years. A total of 800 soil samples from these regions were studied by using kanamycin. The isolated Nocardia species were examined by gram and acid-fast staining and were identified biochemically and morphologically. The frequency and distribution of Nocardia spp. were determined in relation to different factors such as soil pH and temperate climate.

Results

From 153 (19.1%) Nocardia isolates identified, Nocardia asteroids (N. asteroids) complex (45.5%) and Nocardia brasiliensis (N. brasiliensis) (24.7%) were the most frequently isolated species, followed by Nocardia otitidiscaviarum (2.2%), Nocardiopsis dassonvillei, Actinomadura actinomadura (each 1.7%) and Nocardia transvalensis (1.1%) and also unknown spp. (23.0%). In this study, most species (54.4%) of Nocardia, especially N. asteroides complex were isolated from soils with pH: 7.01-8, whereas in pH: 8.01-9 more N. brasiliensis was isolated. The most Nocardia spp. was detected from regions with semi-nomadic and temperate climate (41.1%).

Conclusions

N. asteroids complex is more prevalent in Isfahan province and soil can be a potential source of nocardiosis infections. It is to be considering that climate and soil pH are involved in the frequency and diversity of aerobic Actinomycetes.     

An in vitro microcalorimetric method for studying the toxic effect of cadmium on microbial activity of an agricultural soil

Using TAM III multi-channel thermocalorimetry combined with direct microorganism counting (bacteria, actinomycetes and fungi) under laboratory conditions, we determined the microbial population count, resistance and activity toward cadmium (Cd) toxicity in soil. The thermokinetic parameters, which can represent soil microbial activity, were calculated from power-time curves of soil microbial activity obtained by microcalorimetric measurement. Simultaneous application of the two methods showed that growth rate constant (k), peak-heat output power (P _max) and the number of living microorganisms decreased with increasing concentration of Cd. Anncrease in Cd concentration resulted in the decrease of the peak-heat output power and increase in the time of the peak of power. However, the relationships between the thermokinetic parameters (k and P _max) and the number of microorganism were not linear, but the trend was similar. Our research also suggests that microcalorimetry is a very sensitive, simple and useful technique for in vitro investigation of the effects of toxic heavy metals on soil microbial activity.     

超声萃取-高效液相色谱测定土壤中的氯硝柳胺

目的建立土壤中氯硝柳胺的超声萃取-高效液相色谱检测方法。方法土壤样品经风干研磨过筛后,称取10g加入90 m l甲醇超声萃取3次,应用高效液相色谱分离,紫外检测器检测氯硝柳胺含量。结果方法线性范围为1～100μg/m l,检出限为50μg/kg,相对标准偏差为4.6%（n=7）,样品加标回收率为73.0%～77.4%,平均回收率为75.1%。结论应用超声萃取-高效液相色谱检测土壤中氯硝柳胺含量,操作简便,定量准确,仪器要求低,易于普及。     

Human uptake of persistent chemicals from contaminated soil: PCDD/Fs and PCBs

Trace amounts of polychlorinated dibenzo-p-dioxins/furans (PCDD/Fs) and polychlorinated biphenyls (PCBs) are ubiquitous in the environment. Because of industrial activity, other human activities, and accidents, higher concentrations of these chemicals may be present in soil, in residential and recreational areas. Human uptake of these chemicals from such soils has been assumed by regulators, and people contacting such soils may be concerned about potential adverse health effects. Accordingly, clean up levels have been set by state and federal agencies. Whether and to what extent humans actually take up these chemicals from soil is the focus of this review. Since humans are also exposed to PCDD/Fs and PCBs in food and air, their concentrations in these media are presented. We find that their presence in soils is unlikely to increase human body burdens.     

Ecology and Population Biology of Aflatoxigenic Fungi in Soil

Soil serves as a reservoir for Aspergillus flavus and A. parasiticus, fungi that produce carcinogenic aflatoxins in agricultural commodities. Populations in soil are genetically diverse and individual genotypes show a clustered distribution pattern within fields. Surveys over large geographic regions suggest that climate and crop composition influence species density and aflatoxin‐producing potential. Aflatoxigenic fungi reside in soil as conidia, sclerotia and hyphae, which act as primary inocula for directly infecting peanuts or for infecting aerial crops (corn, cottonseed, tree nuts) through wind and insect dispersal. Infected crops periodically replenish soil populations during drought years.     

Long-term disposition of a novel lipophilic platinum complex SM-11355 in dog after intrahepatic arterial administration: highly sensitive detection of platinum and radioactivity

1. The disposition of SM-11355, an anticancer platinum complex for hepatocellular carcinoma, was investigated in dog by measuring platinum (Pt) and radioactivity levels following intrahepatic arterial administration of ¹⁴C-SM-11355 suspended in Lipiodol, an oily lymphographic agent. Plasma and excretion profiles were monitored in six animals, with tissue distribution studied after 1 day, 4 and 13 weeks (n = 2/time point). 2. SM-11355 was released very slowly into the systemic circulation from Lipiodol, resulting in very low levels of Pt compounds in plasma, urine, faeces and organs. Plasma levels of Pt and radioactivity declined with apparent half-lives of 5-7 weeks. Excretion continued even at 3 months after the administration with proportions excreted for Pt and radioactivity up to 30-60% in urine and 8-10% in faeces. 3. The Pt and radioactivity in the liver accounted for 80-100% of the dose at 1 day and for 20-50% at 13 weeks after the administration, predominately as intact SM-11355. The concentrations were highest in the left lobe of the liver, the administration site, but levels in the remainder of the liver were also markedly higher than those in plasma and other tissues. 4. The results strongly support the concept that SM-11355 targets the liver with highly selectivity and sustained release of Pt compounds.     

利用石墨炉原子吸收分光光度法测定土壤中铬的含量

目的：建立土壤中铬含量的石墨炉原子吸收分光光度测定法.方法：试样经酸消解后,注入原子吸收分光光度计石墨炉中,电热原子化后吸收357.9 nm共振线,在一定浓度范围其吸收值与铬含量成正比,与标准系列比较定量.结果：线性范围为0～20ng/mL,回收率为98％～102％,检出限为0.26ng/mL,相对标准偏差RSD为4.6％.结论：该试验方法具有操作简单,技术条件便于掌握,消解彻底,结果重复性好等优点,可用作土壤中铬含量的测定.     

土壤因子对新疆阿魏挥发油成分的初步研究

目的：研究中药新疆阿魏挥发油成分与其土壤因子的关系。方法：在4个不同样地采集阿魏树脂和土壤样品,通过资料查阅和实地调查,考察产地的生态环境。用气相色谱和GC-MS联用方法分析了药材中的化学成分。结果：4个样地挥发油含量均大于10%,符合国家药典规定。挥发油中成分和相对含量也近乎一致。结论：新疆伊宁县白石墩是新疆阿魏的道地产区。其生长地土壤中有机质（17.4-22.6g/kg）、氮（30.3-46.7mg/kg）、磷（5.5-8.5mg/kg）、钾（182.773mg/kg）养分含量较少,pH值（7.91-8.16）偏碱性,总盐含量（1.0-2.6g/kg）相对较高。     

Effects of long-term fertilization on the diversity of bacterial mercuric reductase gene in a Chinese upland soil

Soil mercury (Hg) pollution has received considerable attention due to its neurotoxin effects and its potential risk to food safety. The microbial transformation of Hg plays a key role in reducing Hg toxicity by the mercuric reductase (MerA) conferred by genes arranged in the mer operon. This study investigated the effects of long‐term fertilization on the diversity of bacterial mercuric reductase gene (merA), which specify the reduction of ionic Hg²⁺ to the volatile elemental form Hg⁰, in an agricultural soil with relatively high Hg content. The soil samples were collected from different treatments, including control without fertilizer (CK), fertilizer nitrogen (N), combined fertilizers (NPK) of N, phosphorus (P) and potassium (K), and NPK plus organic manure (NPK + OM). The merA gene diversity patterns were analyzed based on the merA clone libraries and sequencing measurements. Results showed that the merA gene diversity was influenced by soil variables depending on the fertilization practices. In particular, NH₄⁺ and NO₃^– contents had strong effect on the merA gene diversity pattern both in the N and NPK treatments, whereas the merA gene diversity pattern in NPK + OM treatment was distinctly influenced by the contents of organic matter, available P and K. These results suggested that long‐term fertilization had significant influences on merA gene diversity, which could be helpful to understand the Hg reduction process and potentially serve microbial remediation of Hg contaminated soil. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)