Exogenous compound bacteria enhance the nutrient removal efficiency of integrated bioremediation systems: Functional genes and microorganisms play key roles.

With the continuous development of intensive mariculture, the application of the integrated bioremediation system of aquaculture wastewater (IBSAW) is increasingly promoted. However, the process and nutrients removal performance of the IBSAW need to be further optimized due to its immature technologies. In this study, exogenous compound bacteria (ECB) were added to IBSAW to investigate its pollutants removal efficiency and the relevant mechanisms. High-throughput sequencing and Geochip gene array were used to analyze the correlation between nutrients and bacteria, and the abundance of N and P cycling genes were quantified. Multivariable statistics, dimensionality reduction analysis, and network analysis were applied to explore the mechanisms of IBSAW operation. The results showed that the nutrients decreased significantly after adding ECB, with the brush treatment group significantly outperforming the ceramsite in removing NO3- and PO43-. Ceramsite has an advantage in removing NO2--N. The addition of ECB and different substrates significantly affected the composition of bacterial communities. The contents of nosZ and nirKS related to denitrification in the treatment groups were significantly higher than those in the control group, and the contents in the brush treatment group were significantly higher than that of ceramsite. The biomarkers Psychroserpens and Ruegeria on the biofilm of the brush treatment group were positively correlated with nirKS, while Mycobacterium, Erythrobacter and Paracoccus, Pseudohaliea in the ceramsite group were positively correlated with nirS and nirK, respectively. Therefore, it is speculated that the ECB significantly promoted the increase of denitrification bacteria by affecting the composition of bacterial communities, and the ECB combined with functional genera improved the efficiency of nutrients removal in the system. This study provided a reference for understanding the process and mechanism of nutrients removal, optimizing the wastewater purification technology of the IBSAW and improving the performance of the system.

A novel dehydrocoenzyme activator combined with a composite microbial agent TY for enhanced bioremediation of crude oil-contaminated soil.

Bioaugmentation (BA) and biostimulation (BS) synergistic remediation is an effective remediation strategy for oil-contaminated soil. In this study, the optimal combination system of composite microbial agent TY (Achromobacter: Pseudomona = 2:1) and dehydrocoenzyme activator (NaNO3 (7.0 g/L), (NH4)2HPO4 (1.0 g/L), riboflavin (6.0 mg/L)) was screened. Under the best combination system, the degradation rate of crude oil in oil-contaminated soil reached 79.44% after 60 d, which was 1.74 times and 1.23 times higher than that of compound microbial agent TY treatment and dehydrogenase activator treatment, respectively. In addition, a highly efficient combination system was found to target the degradation of oil C10-C28 fractions by gas chromatography (GC). The increased abundance of dehydrogenase coenzymes such as flavin nucleotides (FAD and FMN), coenzyme I (NAD+, Co I) and coenzyme II (NADP+, Co II) as well as dioxygenases and monooxygenases promote the degradation of crude oil. Furthermore, the dominant genera at the genus level in soil were analyzed by high-throughput sequencing, which were Nocardioides (46.48%-56.07%), Gordonia (11.40%-14.61%), Intrasporangiaceae (5.05%-10.58%), Pseudomonas (1.39%-1.92%) and Dietzia (0.64%-2.77%). Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt) analysis showed that the abundance of genes associated with crude oil degradation such as ABC transporters (2.89%), fatty acid (1.04%), carbon metabolism (4.5%) and aromatic compound (0.92%) was assigned enhanced after 60 d of remediation. These results indicated that the combination system of the compound bacterium TY and the dehydrocoenzyme activator is a propective option for the bioremediation of oil-contaminated soil.

Development of the degradation bacteria in household food waste and analysis of the microbial community in aerobic composting.

By screening the strains and testing different combinations of diverse bacteria, we developed a compound bacterial agent composed of 5 g Bacillus amyloliquefaciens (B2), 10 g Pseudomonas aeruginosa (F4), 5 g Paenibacillus lautus (303), and 10 ml composite strains (DOD) for the degradation of household food waste (HFW). The final mass loss of HFW in aerobic composting with the compound bacteria agent B2+F4+303+DOD (group C) was 84.52%, increased by 20.83% over that loss in natural composting (group A). Analysis of 16S rRNA high-throughput sequencing showed that the phyla in group A and group C mainly included Firmicutes, Proteobacteria, and Cyanobacteria. At the genus level, Pediococcus was the dominant genus in group A, of which the microbial community performed better in maintaining a stable microbial system in the later stage of composting, while Weissella accounted for a larger proportion of group C, which acted well in reducing the final mass of composting. Ochrobactrum was closely related to the removal of odors in the early stage of group C. The relative abundance of compound bacterial agents was always at a rather low level, suggesting that it affected the composting process by changing the proportion of dominant bacteria in the compost.

Exergy analysis and optimization of bio-methane production from corn stalk pretreated by compound bacteria based on genetic algorithm.

An exergy equilibrium model was established to obtain the exergy efficiency under different conditions of compound bacteria pretreatment and anaerobic digestion (AD) of corn stalk. The Genetic Algorithm (GA) was applied to optimize the exergy efficiency of the combination process of the pretreatment and AD. The maximum exergy efficiency with the GA was 19.04%, corresponding to the optimal pretreatment parameters: pretreatment temperature 33.34℃, stalk particle size 0.50 mm, ventilation rate 0.88 L/min, pretreatment time 169.03 h. The optimal AD parameters were: digestion temperature 38.08℃ and stirring rate 48.04 r/min. The validation experiment exergy efficiency reached to 19.25%, which was 24.37% higher as compared to that of the non-pretreatment process. Under these optimal conditions, the energy consumption of the compound bacteria pretreatment and the time of the bio-methane production process were effectively reduced.

Effect of Organophosphate-Solubilizing Bacteria on Photosynthesis， Physiology， and Biochemistry of Paris polyphylla var. yunnanensis / 中国实验方剂学杂志

ObjectiveTo study the effect of organophosphate-solubilizing bacteria and compound bacteria on the photosynthesis and physiological and biochemical characteristics of leaves of Paris polyphylla var. yunnanensis， and to provide a reference for selecting suitable bacterial fertilizers in artificial cultivation of this medicinal species. MethodPot experiment was carried out indoor and the following groups were designed： control （CK）， inoculation with Bacillus mycoides （S1）， inoculation with B. wiedmannii （S2）， inoculation with B. proteolyticus （S3）， inoculation with B. mycoides and B. wiedmannii （S4）， inoculation with B. mycoides and B. proteolyticus （S5）， inoculation with B. wiedmannii and B. proteolyticus （S6）， and inoculation with B. mycoides， B. wiedmannii and B. proteolyticus （S7）. Then， the growth and development， photosynthesis， and various physiological and biochemical indexes of the leaves of this species were observed. ResultCompared with CK， the treatment groups showed decrease in content of malondialdehyde in the leaves （P<0.05）， particularly S7 （content was only about 1/3 that of the CK）. The leaf area， photosynthetic parameters， photosynthetic pigment content， soluble sugar content， soluble protein content， and activity of superoxide dismutase （SOD）， peroxidase （POD）， and catalase （CAT） in leaves of the treatment groups were all improved. Among them， the leaf area， soluble sugar content， and soluble protein content were the highest in S7， which were 2.8， 2.1， and 2.2 times that of the CK， respectively. SOD activity peaked in S6 （2.9 times higher than that in the CK） and the highest activity of POD and CAT was detected in S5 （1.5 times and 2.1 times， respectively higher than that in the CK）. ConclusionInoculation with different organophosphate-solubilizing bacteria or compound bacteria can promote the growth and development of P. polyphylla var. yunnanensis and improve its resistance to stresses. The combination of B. mycoides and B. proteolyticus and the combination of the three achieved the have the best effect. This study provides a reference for the selection of bacterial fertilizers for artificial cultivation of P. polyphylla var. yunnanensis.