Microbial community profiling of the Chinoike Jigoku (“Blood Pond Hell”) hot spring in Beppu,Japan: isolation and characterization of Fe(III)-reducing Sulfolobus sp. strain GA1

Chinoike Jigoku (“Blood Pond Hell”) is located in the hot spring town of Beppu on the southern island of Kyushu in Japan, and is the site of a red-colored acidic geothermal pond. This study aimed to investigate the microbial population composition in this extremely acidic environment and to isolate/characterize acidophilic microorganism with metal-reducing ability. Initially, PCR (using bacteria- and archaea-specific primers) of environmental DNA samples detected the presence of bacteria, but not archaea. This was followed by random sequencing analysis, confirming the presence of wide bacterial diversity at the site (123 clones derived from 18 bacterial and 1 archaeal genera), including those closely related to known autotrophic and heterotrophic acidophiles (Acidithiobacillus sp., Sulfobacillus sp., Alicyclobacillus sp.). Nevertheless, successive culture enrichment with Fe(III) under micro-aerobic conditions led to isolation of an unknown archaeal organism, Sulfolobus sp. GA1 (with 99.7% 16S rRNA gene sequence identity with Sulfolobus shibatae). Unlike many other known Sulfolobus spp., strain GA1 was shown to lack sulfur oxidation ability. Strain GA1 possessed only minor Fe(II) oxidation ability, but readily reduced Fe(III) during heterotrophic growth under micro-aerobic conditions. Strain GA1 was capable of reducing highly toxic Cr(VI) to less toxic/soluble Cr(III), demonstrating its potential utility in bioremediation of toxic metal species.     

Comparative proteomics of Acidithiobacillus ferrooxidans grown in the presence and absence of uranium

Acidithiobacillus ferrooxidans is an acidophile that thrives in metal-contaminated environments and tolerates high levels of uranium. To gain a better understanding of the processes involved in U(VI) resistance, comparative proteomics was used. The proteome of A. ferrooxidans was grown in the presence and absence of 0.5 mM U(VI); expression of 17 proteins was upregulated and one was downregulated. Most proteins with increased expression are part of the general stress response or are involved in reactive oxygen species detoxification. Four novel proteins showed increased expression in the presence of U(VI) and may contribute to U(VI) resistance via thiol homoeostasis and U(VI) binding.     

Response to copper of Acidithiobacillus ferrooxidans ATCC 23270 grown in elemental sulfur

The response of Acidithiobacillus ferrooxidans ATCC 23270 to copper was analyzed in sulfur-grown cells by using quantitative proteomics. Fortyseven proteins showed altered levels in cells grown in the presence of 50 mM copper sulfate. Of these proteins, 24 were up-regulated and 23 down-regulated. As seen before in ferrous iron-grown cells, there was a notorious up-regulation of RND-type Cus systems and different RND-type efflux pumps, indicating that these proteins are very important in copper resistance. Copper also triggered the down-regulation of the major outer membrane porin of A. ferrooxidans in sulfur-grown bacteria, suggesting they respond to the metal by decreasing the influx of cations into the cell. On the contrary, copper in sulfur-grown cells caused an overexpression of putative TadA and TadB proteins known to be essential for biofilm formation in bacteria. Surprisingly, sulfur-grown microorganisms showed increased levels of proteins related with energy generation (rus and petII operons) in the presence of copper. Although rus operon is overexpressed mainly in cells grown in ferrous iron, the up-regulation of rusticyanin in sulfur indicates a possible role for this protein in copper resistance as well. Finally, copper response in A. ferrooxidans appears to be influenced by the substrate being oxidized by the microorganism.     

Insights into the pathways of iron- and sulfur-oxidation,and biofilm formation from the chemolithotrophic acidophile Acidithiobacillus ferrivorans CF27

The iron-oxidizing acidithiobacilli cluster into at least four groups, three of which (Acidithiobacillus ferrooxidans, Acidithiobacillus ferridurans and Acidithiobacillus ferrivorans) have been designated as separate species. While these have many physiological traits in common, they differ in some phenotypic characteristics including motility, and pH and temperature minima. In contrast to At. ferrooxidans and At. ferridurans, all At. ferrivorans strains analysed to date possess the iro gene (encoding an iron oxidase) and, with the exception of strain CF27, the rusB gene encoding an iso-rusticyanin whose exact function is uncertain. Strain CF27 differs from other acidithiobacilli by its marked propensity to form macroscopic biofilms in liquid media. To identify the genetic determinants responsible for the oxidation of ferrous iron and sulfur and for the formation of extracellular polymeric substances, the genome of At. ferrivorans CF27 strain was sequenced and comparative genomic studies carried out with other Acidithiobacillus spp.. Genetic disparities were detected that indicate possible differences in ferrous iron and reduced inorganic sulfur compounds oxidation pathways among iron-oxidizing acidithiobacilli. In addition, strain CF27 is the only sequenced Acidithiobacillus spp. to possess genes involved in the biosynthesis of fucose, a sugar known to confer high thickening and flocculating properties to extracellular polymeric substances.     

Electricity generation from an inorganic sulfur compound containing mining wastewater by acidophilic microorganisms

Sulfide mineral processing often produces large quantities of wastewaters containing acid-generating inorganic sulfur compounds. If released untreated, these wastewaters can cause catastrophic environmental damage. In this study, microbial fuel cells were inoculated with acidophilic microorganisms to investigate whether inorganic sulfur compound oxidation can generate an electrical current. Cyclic voltammetry suggested that acidophilic microorganisms mediated electron transfer to the anode, and that electricity generation was catalyzed by microorganisms. A cation exchange membrane microbial fuel cell, fed with artificial wastewater containing tetrathionate as electron donor, reached a maximum whole cell voltage of 72 ± 9 mV. Stepwise replacement of the artificial anolyte with real mining process wastewater had no adverse effect on bioelectrochemical performance and generated a maximum voltage of 105 ± 42 mV. 16S rRNA gene sequencing of the microbial consortia resulted in sequences that aligned within the genera Thermoplasma, Ferroplasma, Leptospirillum, Sulfobacillus and Acidithiobacillus. This study opens up possibilities to bioremediate mining wastewater using microbial fuel cell technology.     

Genomic and metagenomic challenges and opportunities for bioleaching: a mini-review

High-throughput genomic technologies are accelerating progress in understanding the diversity of microbial life in many environments. Here we highlight advances in genomics and metagenomics of microorganisms from bioleaching heaps and related acidic mining environments. Bioleaching heaps used for copper recovery provide significant opportunities to study the processes and mechanisms underlying microbial successions and the influence of community composition on ecosystem functioning. Obtaining quantitative and process-level knowledge of these dynamics is pivotal for understanding how microorganisms contribute to the solubilization of copper for industrial recovery. Advances in DNA sequencing technology provide unprecedented opportunities to obtain information about the genomes of bioleaching microorganisms, allowing predictive models of metabolic potential and ecosystem-level interactions to be constructed. These approaches are enabling predictive phenotyping of organisms many of which are recalcitrant to genetic approaches or are unculturable. This mini-review describes current bioleaching genomic and metagenomic projects and addresses the use of genome information to: (i) build metabolic models; (ii) predict microbial interactions; (iii) estimate genetic diversity; and (iv) study microbial evolution. Key challenges and perspectives of bioleaching genomics/metagenomics are addressed.     

Mechanism of quinolone resistance in anaerobic bacteria

Several recently developed quinolones have excellent activity against a broad range of aerobic and anaerobic bacteria and are thus potential drugs for the treatment of serious anaerobic and mixed infections. Resistance to quinolones is increasing worldwide, but is still relatively infrequent among anaerobes. Two main mechanisms, alteration of target enzymes (gyrase and topoisomerase IV) caused by chromosomal mutations in encoding genes, or reduced intracellular accumulation due to increased efflux of the drug, are associated with quinolone resistance. These mechanisms have also been found in anaerobic species. High-level resistance to the newer broad-spectrum quinolones often requires stepwise mutations in target genes. The increasing emergence of resistance among anaerobes may be a consequence of previous widespread use of quinolones, which may have enriched first-step mutants in the intestinal tract. Quinolone resistance in the Bacteroides fragilis group strains is strongly correlated with amino acid substitutions at positions 82 and 86 in GyrA (equivalent to positions 83 and 87 of Escherichia coli ). Several studies have indicated that B. fragilis group strains possess efflux pump systems that actively expel quinolones, leading to resistance. DNA gyrase seems also to be the primary target for quinolones in Clostridium difficile , since amino acid substitutions in GyrA and GyrB have been detected in resistant strains. To what extent other mechanisms, such as mutational events in other target genes or alterations in outer-membrane proteins, contribute to resistance among anaerobes needs to be further investigated.     

Differential utilization and transformation of sulfur allotropes, μ-S and α-S8, by moderate thermoacidophile Sulfobacillus thermosulfidooxidans

The utilization of amorphous μ-S and orthorhombic α-S₈ by thermoacidophile Sulfobacillus thermosulfidooxidans was firstly investigated in terms of cell growth and sulfur oxidation behavior. The morphology and surface sulfur speciation transformation were evaluated by using scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform-infrared spectroscopy (FT-IR), Raman spectroscopy and sulfur K-edge X-ray absorption near edge structure (XANES) spectroscopy. The results showed that the strain grown on μ-S entered slower (about 1 day later) into the exponential phase, while grew faster in exponential phase and attained higher maximal cell density and lower pH than on α-S₈. After bio-corrosion, both sulfur samples were evidently eroded, but only μ-S surface presented much porosity, while α-S₈ maintained glabrous. μ-S began to be gradually converted into α-S₈ from day 2 when the bacterial cells entered the exponential phase, with a final composition of 62.3% μ-S and 37.7% α-S₈ on day 4 at the stationary phase. α-S₈ was not found to transform into other species in the experiments with or without bacteria. These data indicated S. thermosulfidooxidans oxidized amorphous μ-S faster than orthorhombic α-S₈, but the chain-like μ-S was transformed into cyclic α-S₈ by S. thermosulfidooxidans.     

The aerobic energy metabolism of the juvenile Fasciola hepatica

Juvenile Fasciola hepatica were isolated immediately after in vitro emergence from the metacercarial cysts and incubated with uniformly labelled glucose. Under aerobic conditions, carbon dioxide was the main end product of glucose breakdown. In the absence of oxygen, glucose was fermented mainly to propionate and acetate in a molar ratio of 2 : 1, with lactate as a minor product. This anaerobic end-product pattern closely resembles that of the adult liver fluke. In the presence of oxygen and 1 mM cyanide, lactate accumulated. The difference between anaerobic glucose breakdown and that in the presence of cyanide is explained by an inhibitory effect of cyanide on the malic enzyme (EC 1.1.1.40) of the juvenile mitochondria. A substantial Pasteur effect is calculated from these incubations. The oxygen consumption of the juveniles was completely cyanide-sensitive. From these results it is concluded that in aerobic conditions the juvenile liver flukes have an aerobic energy metabolism. Since they can survive prolonged periods of anaerobiosis, they should be called facultative anaerobes.     

妊娠期铁缺乏和缺铁性贫血的补铁治疗

铁是人体内重要的微量元素,轻度的铁元素不足会导致单纯性铁缺乏（ID）,而严重者会进展为缺铁性贫血（IDA）。妊娠期妇女因其生理特殊性,对铁元素的需求量更大,更易发生铁缺乏。妊娠期贫血会对母体及胎儿、新生儿造成近期或远期的不良影响。安全有效的纠正妊娠期妇女的贫血状态显得尤为重要。因此,本文对妊娠期如何纠正铁缺乏、缺铁性贫血进行综述,旨在为临床诊治妊娠期铁缺乏及缺铁性贫血孕妇提供参考。     

益气补血法联合小剂量铁剂治疗对缺铁性贫血患儿的疗效分析

目的 分析益气补血法联合小剂量铁剂治疗对缺铁性贫血患儿的临床疗效。方法 选择本院2016年4月~2017年4月122例缺铁性贫血患儿的临床资料,随机分为对照组与研究组,每组61例,对照组实施小剂量的铁剂治疗,研究组实施益气补血法与小剂量铁剂联合治疗,分析两组铁代谢有关指标变化情况及治疗效果。结果 研究组SI（血清铁）及SF(铁蛋白)水平比对照组高,TIBC（总铁结合力）比对照组更低,研究组治疗效果高于对照组,存在统计学差异(P＜0.05)。结论 益气补血法联合小剂量铁剂治疗对缺铁性贫血患儿的临床疗效显著,值得推广。     

209例6个月～2岁儿童铁营养调查与分析

目的 研究婴幼儿早期缺铁的临床指标，为缺铁的早期诊断提供理论依据。方法 选取209例在门诊进行健康体检的婴幼儿，年龄6月～2岁，按不同月龄分为6月～1岁，1岁～2岁各2组，测定其末梢血系列，主要包括RBC、Hb、MCV、MCH、MCHC、RDW指标，资料应用SPSS12．5软件进行Х^2检验。结果 （1）RBC、Hb、MCHC的均值均在正常范围内；（2）MCV、MCH、RDW均数均低于正常值范围，其中MCH值在两组间有显著性差异（P〈0．05）。结论 （1）本组RDW、MCV、MCH的异常是诊断缺铁的重要指标，它的异常较其它指标出现要早。（2）婴幼儿辅食添加情况可直接决定其体内铁营养的状况。     

力蜚能治疗小儿缺铁性贫血的疗效观察

目的探讨多糖铁复合物力蜚能治疗小儿缺铁性贫血的疗效观察。方法60例患儿随机分为力蜚能治疗组和硫酸亚铁治疗组,前者给予力蜚能治疗;后者给予硫酸亚铁和维生素C治疗。结果治疗8周后力蜚能治疗组的血清铁（SI）水平明显高于硫酸亚铁治疗组（P〈0.01）;力蜚能治疗组的总有效率高于硫酸亚铁治疗组（P〈0.05）,且不良反应有显著性差异（P〈0.01）。结论力蜚能治疗小儿缺铁性贫血的疗效优于硫酸亚铁,且不良反应少,是治疗小儿缺铁性贫血的理想药物。     

In vitro cytokine production in patients with iron deficiency anemia

The in vitro production of interleukin (IL)-1beta, IL-2, IL-6, IL-10, and tumor necrosis factor alpha (TNFalpha) by peripheral blood mononuclear cells (PBMC) from 20 patients with iron deficiency anemia (IDA) was examined before and after iron supplementation and compared to values obtained for PBMC from healthy controls. A significant decrease in IL-2 production was observed in IDA patients, whereas the secretion of the other cytokines did not differ from that of controls. Addition of iron to the culture medium did not affect the secretion of IL-2 and IL-1beta, but caused an increase in IL-6, IL-10, and TNF-alpha production. Since a deficiency in IL-2 production plays a role in the pathogenesis of certain infectious and malignant diseases, the results of the present study may explain in part the increased susceptibility to infections observed in patients with IDA.