Influence of the autochthonous cellulolytic bacteria on the domestic compost process improvement.

This work aimed to determine the influence of the inoculation of autochthonous cellulolytic bacteria on the composting process without any modifications of physical or chemical parameters. Bacteria with cellulolytic abilities were isolated from composted material containing food and plant leftovers and identified as Bacillus licheniformis, Bacillus altitudinis, and Lysinibacillus xylanilyticus. The experimental composter containing garden and household wastes was inoculated with bio-vaccine prepared as a mixture of isolated cellulolytic bacterial strains and composted for the next 96 days parallelly to the control composter without the inoculation. During the experiment, changes in temperature, humidity, the content of the humic acids (HAs), organic carbon, nitrogen, and C : N ratio were determined. As the particular microbial groups play a key role in the composting process, the biodiversity of the microorganisms present in the composter as well as the number of psychrophilic, mesophilic, and sporeforming microorganisms, Actinomycetes, and fungi were analyzed. The changes in the abundance of particular bacterial groups were convergent with temperature changes in the temperature of composting material. The composting material inoculated with autochthonous microorganisms was characterized by higher HA content and lower biodiversity. The inoculation with autochthonous microorganisms positively influenced the composting material in the corners for the entire process and in the middle of the container for 61 days. Thus, the effect of inoculation depended on the localization of the process inside the container subjected to biopreparation.

Effect of biomass immobilization and reduced graphene oxide on the microbial community changes and nitrogen removal at low temperatures.

The slow growth rate and high optimal temperatures for the anaerobic ammonium oxidation (anammox) bacteria are significant limitations of the anammox processes application in the treatment of mainstream of wastewater entering wastewater treatment plant (WWTP). In this study, we investigate the nitrogen removal and microbial community changes in sodium alginate (SA) and sodium alginate-reduced graphene oxide (SA-RGO) carriers, depending on the process temperature, with a particular emphasis on the temperature close to the mainstream of wastewater entering the WWTP. The RGO addition to the SA matrix causes suppression of the beads swelling, which intern modifies the mechanical properties of the gel beads. The effect of the temperature drop on the nitrogen removal rate was reduced for biomass entrapped in SA and SA-RGO gel beads in comparison to non-immobilized biomass, this suggests a ''protective" effect caused by immobilization. However, analyses performed using next-generation sequencing (NGS) and qPCR revealed that the microbial community composition and relative gene abundance changed significantly, after the implementation of the new process conditions. The microbial community inside the gel beads was completely remodelled, in comparison with inoculum, and denitrification contributed to the nitrogen transformation inside the beads.

Medium shift influence on nitrogen removal bacteria: Ecophysiology and anammox process performance.

In this study, we focused on the proportion of particular bacterial groups and changes in microbial community structure in relation to the anammox process parameters and the feeding medium strategy in the Sequencing Batch Reactor (SBR). In order to present an insight into the microbial dynamics while feeding medium shift from synthetic wastewater to landfill leachate, fluorescent in situ hybridization (FISH), Real Time PCR, PCR - DGGE (Polymerase Chain Reaction-Denaturing Gradient Gel Electrophoresis) and Reverse Transcription PCR-DGGE analysis were used. Feeding medium change has the strongest impact on relative abundance of denitrifiers and representatives of Planctomycetes. The relative abundancy of specific genes for all investigated nitrogen removal bacterial groups dropped after landfill leachate implementation. However, anammox consortium were able to adapt to the new reactor operating conditions and time for adaptation was estimated at the level of 90 days.