Diversity of lactic acid bacteria of the bioethanol process

Background  

Bacteria may compete with yeast for nutrients during bioethanol production process, potentially causing economic losses. This is the first study aiming at the quantification and identification of Lactic Acid Bacteria (LAB) present in the bioethanol industrial processes in different distilleries of Brazil.     

Glycoprotein 60 diversity in C. hominis and C. parvum causing human cryptosporidiosis in NSW, Australia

Management and control of cryptosporidiosis in human requires knowledge of Cryptosporidium species contributing to human disease. Markers that are able to provide information below the species level have become important tools for source tracking. Using the hypervariable surface antigen, glycoprotein 60 (GP60), C. hominis (n = 37) and C. parvum (n = 32) isolates from cryptosporidiosis cases in New South Wales, Australia, were characterised. Extensive variation was observed within this locus and the isolates could be divided into 8 families and 24 different subtypes. The subtypes identified have global distributions and indicate that anthroponotic and zoonotic transmission routes contribute to sporadic human cryptosporidiosis in NSW.     

LINEAGES THAT CHEAT DEATH: SURVIVING THE SQUEEZE ON RANGE SIZE

Evolutionary lineages differ greatly in their net diversification rates, implying differences in rates of extinction and speciation. Lineages with a large average range size are commonly thought to have reduced extinction risk (although linking low extinction to high diversification has proved elusive). However, climate change cycles can dramatically reduce the geographic range size of even widespread species, and so most species may be periodically reduced to a few populations in small, isolated remnants of their range. This implies a high and synchronous extinction risk for the remaining populations, and so for the species as a whole. Species will only survive through these periods if their individual populations are “threat tolerant,” somehow able to persist in spite of the high extinction risk. Threat tolerance is conceptually different from classic extinction resistance, and could theoretically have a stronger relationship with diversification rates than classic resistance. I demonstrate that relationship using primates as a model. I also show that narrowly distributed species have higher threat tolerance than widespread ones, confirming that tolerance is an unusual form of resistance. Extinction resistance may therefore operate by different rules during periods of adverse global environmental change than in more benign periods.     

Capillary circular dichroism

Circular dichroism (CD) has become an increasingly important tool in the study of biological molecules as it enables structural information to be obtained nondestructively on solution-phase samples. However, sample requirements for CD are often seen as being too high with protein backbone measurements in standard cuvettes typically requiring ～100-300 μL of 0.1 mg/ml protein. To address this issue, we have designed a new form of CD sample holder, which reduces the sample requirements of the technique by two orders of magnitude, with a sample requirement of less than 3 μl. This sample saving has been achieved through the use of extruded quartz capillaries, the sample being held within the internal diameter of the quartz capillary through capillary action. The extruded quartz capillaries exhibit remarkably little birefringence, although still transmitting high energy UV circularly polarized light. The optics associated with capillaries were investigated. A configuration has been adopted with the light beam of the spectrophotometer being focused in front of the front face of the capillary using a biconvex lens and advantage being taken of the additional focusing effect of the capillary itself. The focusing is vital to the low wavelength performance of the cell, where we have acquired reliable data down to 180 nm using a Jasco J-815 spectrophotometer. The system performance was validated with Na[Co(EDDS)].H(2)O (EDDS = N,N-ethylenediaminedisuccinic acid), concanavalin A, lysozyme, and progesterone.     

NMR structural analysis of the soluble domain of ZiaA-ATPase and the basis of selective interactions with copper metallochaperone Atx1

A Cu(I) metallochaperone, Atx1, interacts with the amino-terminal domain of a Cu(I)-transporting ATPase, PacS_N, but not with a domain of related Zn-transporting ATPase, ZiaA_N in Synechocystis PCC 6803. This is thought to prevent ZiaA_N from acquiring Cu(I), which it binds more tightly than Zn. Solution structures of Atx1, PacS_N, and the heterodimer were previously described. Here we report solution structural studies of the ZiaA_N soluble domain. Apo-ZiaA_N has a typical ferredoxin-like fold followed by an atypical 34 residues of unstructured polypeptide containing a His₇ motif. ZiaA_N competes with the metallochromic indicator 4-(2-pyridylazo)resorcinol for 1 equiv of Zn, which can be displaced by thiol-modifying p-mercuriphenylsulfonic acid, establishing that a high-affinity site involves thiols of the CXXC motif within the ferredoxin-like fold. A single equivalent of Zn affects nuclear magnetic resonance signals arising from the CXXC motif as well as all seven His residues. The presence of NMR-line broadening in both sites implies that Zn₁-ZiaA_N undergoes exchange phenomena, consistent with CXXC-bound Zn coincidentally sampling various His ligands. These Zn-dependent dynamic changes could either aid metal transfer or alter intramolecular interactions. No formation of Atx1–Cu(I)–ZiaA_N heterodimers was observed, and in the presence of equimolar ZiaA_N and PacS_N, only Atx1–Cu(I)–PacS_N complexes were detected. Residues flanking the CXXC motif of PacS_N (R₁₃-ASS₂₀) differ in charge and bulk from those of ZiaA_N (D₁₈-KLK₂₅) and make contacts in the Atx1–Cu(I)–PacS_N complex. Crucially, swapping these residues flanking the CXXC motifs of ZiaA_N and PacS_N reciprocally swaps partner choice by Atx1. These few residues of the two ATPases have diverged during evolution to bias Atx1 interactions in favor of PacS_N rather than ZiaA_N.     

Molecular epidemiology, spatiotemporal analysis, and ecology of sporadic human cryptosporidiosis in Australia

Parasites from the Cryptosporidium genus are the most common cause of waterborne disease around the world. Successful management and prevention of this emerging disease requires knowledge of the diversity of species causing human disease and their zoonotic sources. This study employed a spatiotemporal approach to investigate sporadic human cryptosporidiosis in New South Wales, Australia, between January 2008 and December 2010. Analysis of 261 human fecal samples showed that sporadic human cryptosporidiosis is caused by four species; C. hominis, C. parvum, C. andersoni, and C. fayeri. Sequence analysis of the gp60 gene identified 5 subtype families and 31 subtypes. Cryptosporidium hominis IbA10G2 and C. parvum IIaA18G3R1 were the most frequent causes of human cryptosporidiosis in New South Wales, with 59% and 16% of infections, respectively, attributed to them. The results showed that infections were most prevalent in 0- to 4-year-olds. No gender bias or regional segregation was observed between the distribution of C. hominis and C. parvum infections. To determine the role of cattle in sporadic human infections in New South Wales, 205 cattle fecal samples were analyzed. Four Cryptosporidium species were identified, C. hominis, C. parvum, C. bovis, and C. ryanae. C. parvum subtype IIaA18G3R1 was the most common cause of cryptosporidiosis in cattle, with 47% of infections attributed to it. C. hominis subtype IbA10G2 was also identified in cattle isolates.     

Molecular epidemiology and spatial distribution of a waterborne cryptosporidiosis outbreak in Australia

Cryptosporidiosis is one of the most common waterborne diseases reported worldwide. Outbreaks of this gastrointestinal disease, which is caused by the Cryptosporidium parasite, are often attributed to public swimming pools and municipal water supplies. Between the months of January and April in 2009, New South Wales, Australia, experienced the largest waterborne cryptosporidiosis outbreak reported in Australia to date. Through the course of the contamination event, 1,141 individuals became infected with Cryptosporidium. Health authorities in New South Wales indicated that public swimming pool use was a contributing factor in the outbreak. To identify the Cryptosporidium species responsible for the outbreak, fecal samples from infected patients were collected from hospitals and pathology companies throughout New South Wales for genetic analyses. Genetic characterization of Cryptosporidium oocysts from the fecal samples identified the anthroponotic Cryptosporidium hominis IbA10G2 subtype as the causative parasite. Equal proportions of infections were found in males and females, and an increased susceptibility was observed in the 0- to 4-year age group. Spatiotemporal analysis indicated that the outbreak was primarily confined to the densely populated coastal cities of Sydney and Newcastle.     

An Off-Line Implementation of the Stable Isotope Technique for Measurements of Alternative Respiratory Pathway Activities

In situ measurements of alternative respiratory pathway activity are needed to provide insight into the energy efficiency of plant metabolism under various conditions in the field. The only reliable method at present to measure alternative oxidase (AOX) activity is through measurement of changes in delta(18)O(O(2)), which to date has only been used in laboratory environments. We have developed a cuvette system to measure partitioning of electrons to AOX that is suitable for off-line use and for field experiments. Plant samples are enclosed in airtight cuvettes and O(2) consumption is monitored. Gas samples from the cuvette are stored in evacuated gas containers until measurement of delta(18)O(O(2)). We have validated this method using differing plant material to assess AOX activity. Fractionation factors were calculated from delta(18)O(O(2)) measurements, which could be measured with an accuracy and precision to 0.1 per thousand and 0.3 per thousand, respectively. Potential sources of error are discussed and quantified. Our method provides results similar to those obtained with laboratory incubations on-line to a mass spectrometer but greatly increases the potential for adoption of the stable isotope method.