Field-based methods for measuring greenhouse gases emissions from on-site sanitation systems: A systematic review of published literature.

On-site sanitation systems (OSS) are a source of greenhouse gas (GHG) emissions. Although efforts have been made recently to measure and quantify emissions from septic tanks using various field-based methods, the vast majority of published literature reporting GHG emissions from OSS units (e.g., pits and tanks) is based on non-empirical evidence. This systematic review presents an overview and limitations of field-based methods used for the quantification of GHG emissions from OSS. Papers published in English were searched in three databases: Google Scholar, PubMed, and Directory of Articles and Journals. Peer-reviewed papers that reported field-based methods applied to containment units in OSS were included in this study. Only eight out of 2085 papers met the inclusion criteria with septic tanks as the sole technology reported and were thus, considered for the review. Most of the studies have been conducted in middle- and high-income countries. Field-based measurements of GHGs are conducted using a flux chamber (FC) and the most commonly used FC methods are (a) the modified simple static FC, (b) automated static FC, and (c) floating FC. Data reported in published studies do not provide sufficient information on the calibration and validation of the results from the FCs used. The complex FC designs, laborious fieldwork operations, and reliance on expensive, specialist equipment, suggest that such methods may not be suitable in Low and Middle-Income countries (LMICs), where resources and access to laboratory facilities are limited. Also, the complexity of pits and tank typology in LMICs (i.e., unstandardised designs and sizes) may be a challenge to the use of FCs with fixed dimensions and set operational conditions. The variation in the quantification methods and resulting emission rates among the studies indicates that gaps prevail in the use of existing methods. Therefore, there is still a need for a simple field-based, easily adaptable FC method with adequate calibration and validation that can help in reliably quantifying the emissions from different OSS in any LMICs.

Genome-wide analysis of cytosine DNA methylation revealed salicylic acid promotes defense pathways over seedling development in pearl millet.

Cytosine DNA methylation is an epigenetic regulatory system used by plants to control gene expression. Methylation pattern always changes after abiotic stresses, pathogens and pest infections or after a treatment with salicylic acid (SA). The latter is a key player in plant development and defense against insect herbivores, pathogens, and abiotic stresses. The roles of SA on the methylation patterns and the plant development were performed in 4 pearl millet (Pennisetum glaucum) varieties. Seedlings of 4 early-flowering photosensitive genotypes (PMS3, PMI8, PMG, and PMT2) were grown on MS medium supplemented with null or different doses of SA. Root growth was used as a parameter to evaluate the effects of SA at early stage development. DNA from these seedlings was extracted and Methylation-Sensitive Amplified Polymorphism (MSAP) was measured to assess the effects of SA on methylome. The methylation analysis revealed that SA treatment decreased the methylation, while inhibiting the root growth for all varieties tested, except in PMG at 0.5 mM, indicating a dose and a genotype response-dependence. The methylation level was positively correlated with the root growth. This suggests that SA influences both the methylome by demethylation activities and the root growth by interfering with the root development-responsive genes. The demethylation process, induced by the REPRESSOR OF SILCENCING 1 (ROS1) may activate R genes, or GH3.5 and downregulate the hormonal pathway under root development. These findings showed the pearl millet metabolism prioritized and promoted the defense pathways over vegetative development during stress.

Use of an acidophilic yeast strain to enable the growth of leaching bacteria on solid media.

In this study, a Candida digboiensis strain was isolated from a heap leaching plant in Zambia and used in double-layer agar plate to efficiently isolate and purify leaching bacteria. Unlike Acidiphilium sp., the yeast strain was tetrathionate tolerant and could metabolize a great range of organic compounds including organic acids. These properties allowed the yeast strain to enable and fasten the growth of iron and sulfur oxidizers on double-layer agar plate. The isolates were identified as Acidithiobacillus ferrooxidans FOX1, Leptospirillun ferriphilum BN, and Acidithiobacillus thiooxidans ZMB. These three leaching bacteria were inhibited by organic acids such as acetic and propionic acids; however, their activities were enhanced by Candida digboiensis NB under dissolved organic matter stress.

Cross-comparison of leaching strains isolated from two different regions: Chambishi and Dexing copper mines.

A cross-comparison of six strains isolated from two different regions, Chambishi copper mine (Zambia, Africa) and Dexing copper mine (China, Asia), was conducted to study the leaching efficiency of low grade copper ores. The strains belong to the three major species often encountered in bioleaching of copper sulfide ores under mesophilic conditions: Acidithiobacillus ferrooxidans, Acidithiobacillus thiooxidans, and Leptospirillum ferriphilum. Prior to their study in bioleaching, the different strains were characterized and compared at physiological level. The results revealed that, except for copper tolerance, strains within species presented almost similar physiological traits with slight advantages of Chambishi strains. However, in terms of leaching efficiency, native strains always achieved higher cell density and greater iron and copper extraction rates than the foreign microorganisms. In addition, microbial community analysis revealed that the different mixed cultures shared almost the same profile, and At. ferrooxidans strains always outcompeted the other strains.

MCQTL: multi-allelic QTL mapping in multi-cross design.

UNLABELLED: The aim of the MCQTL software package is to perform QTL mapping in multi-cross designs. It allows the analysis of the usual populations derived from inbred lines and can link the families by assuming that the QTL locations are the same in all of them. Moreover, a diallel modelling of the QTL genotypic effects is allowed in multiple related families. The implemented model is a linear regression model. A composite interval mapping and an iterative QTL mapping are implemented to deal with multiple QTL models. Marker cofactor selections by forward or backward stepwise methods are implemented as well as computation of threshold test value by permutation. AVAILABILITY: The program is available on request after signing a licence agreement; free of charge for academic and non-profit organizations at http://www.genoplante.org (Bioinformatics products).