The bacteriome of the halophyte Atriplex nummularia (old man saltbush) in salt-affected soils - an ecological model.

Halophytes, plants capable of growing under saline conditions, are an important source of bacteria with biotechnological potential for plant growth under extreme conditions. In this study, we evaluated the halophyte Atriplex nummularia bacteriome assemblage from three different salinized sites in northeastern Brazil with different edaphoclimatic characteristics, understanding the participation of the plant in the assembly of its microbiome. We sampled 30 specimens, from which the leaves, roots, and rhizospheric soil were subjected to 16S rRNA gene sequencing, bringing forth patterns of alpha and beta diversity, taxonomical composition, co-occurrence network, and the core microbiome of each compartment. Overall, this species harbors a very restricted set of endophytic microbes, and communities showed an increasing gradient of complexity (soil > root > leaf), reflecting a change in the main selective pressure being active over the microbial community. Although the leaf bacteriome was influenced basically by host factors, the soil community was modulated by the environment, and the root bacteriome was structured by both factors. These results help us understand how plant-microbe interactions occur in saline environments. As these plants shelter microbes that potentially alleviate abiotic stresses, we discuss how culture-independent methods could contribute to the prospection of plant growth promoting bacteria in plants.

Identification, Characterization, and Optimization of Split Inteins.

In recent years, split inteins have seen widespread use as molecular platforms for the design of a variety of peptide and protein chemistry technologies, most notably protein ligation. The development of these approaches is dependent on the identification and/or design of split inteins with robust activity, stability, and solubility. Here, we describe two approaches to characterize and compare the activities of newly identified or engineered split inteins. The first assay employs an E. coli-based selection system to rapidly screen the activities of many inteins and can be repurposed for directed evolution. The second assay utilizes reverse-phase high-performance liquid chromatography (RP-HPLC) to provide insights into individual chemical steps in the protein splicing reaction, information that can guide further engineering efforts. These techniques provide useful alternatives to common assays that utilize SDS-PAGE to analyze splicing reaction progress.

Bacterial Selection during the Formation of Early-Stage Aerobic Granules in Wastewater Treatment Systems Operated Under Wash-Out Dynamics.

Aerobic granular sludge is attractive for high-rate biological wastewater treatment. Biomass wash-out conditions stimulate the formation of aerobic granules. Deteriorated performances in biomass settling and nutrient removal during start-up have however often been reported. The effect of wash-out dynamics was investigated on bacterial selection, biomass settling behavior, and metabolic activities during the formation of early-stage granules from activated sludge of two wastewater treatment plants (WWTP) over start-up periods of maximum 60 days. Five bubble-column sequencing batch reactors were operated with feast-famine regimes consisting of rapid pulse or slow anaerobic feeding followed by aerobic starvation. Slow-settling fluffy granules were formed when an insufficient superficial air velocity (SAV; 1.8 cm s(-1)) was applied, when the inoculation sludge was taken from a WWTP removing organic matter only, or when reactors were operated at 30°C. Fast-settling dense granules were obtained with 4.0 cm s(-1) SAV, or when the inoculation sludge was taken from a WWTP removing all nutrients biologically. However, only carbon was aerobically removed during start-up. Fluffy granules and dense granules were displaying distinct predominant phylotypes, namely filamentous Burkholderiales affiliates and Zoogloea relatives, respectively. The latter were predominant in dense granules independently from the feeding regime. A combination of insufficient solid retention time and of leakage of acetate into the aeration phase during intensive biomass wash-out was the cause for the proliferation of Zoogloea spp. in dense granules, and for the deterioration of BNR performances. It is however not certain that Zoogloea-like organisms are essential in granule formation. Optimal operation conditions should be elucidated for maintaining a balance between organisms with granulation propensity and nutrient removing organisms in order to form granules with BNR activities in short start-up periods.