•Microbial communities of mature and growing aerobic granules were probed.•Sliced sample study showed a spherical core with anaerobic Rhodocyclaceae.•High-throughput sequencing showed that flocs were ...transited to young granules.•Microbial community data supported deterministic mechanism for granulation.
Aerobic granulation is an advanced biological wastewater treatment technology. This study for the first time identified the microbial communities of sliced samples of mature granules by polymerase chain reaction (PCR) amplification and denaturing gradient gel electrophoresis (DGGE) technique and those of whole growing granules by high-throughput sequencing technique. The sliced sample study revealed that mature granules have a spherical core with anaerobic Rhodocyclaceae covered by an outer spherical shell with both aerobic and anaerobic strains. The growing granule study showed that the flocculated flocs were first transited to young granules with increased abundances of Flavobacteriaceae, Xanthomonadaceae, Rhodobacteraceae and Microbacteriaceae, then the abundances of anaerobic strains were increased owing to the formation of anaerobic core. Since the present granules were cultivated from flocculated flocs, the microbial community data suggested that granules were formed via a deterministic rather than via a random aggregation–disintegration mechanism.
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•COD and UV absorbance were effectively reduced (>90%).•The final effluent was non-toxic to Artemia salina and Microtox.•DGGE was used to detect bacteria and eukaryotes in the ...biological process.•Algae were detected for the first time in a reactor treating textile effluent.
Many commercial dye preparations are cocktails of active dyes and various by-products that are recalcitrant to biological degradation and end up in significant amounts in the effluent after the dyeing process. Conventional wastewater treatment processes are not able to degrade such compounds and detoxify the effluent, thus alternative treatments should be developed.
In our work we suggest to use photo-Fenton oxidation as post-treatment after an anaerobic biofilm process, in a way to minimize the reagents needed. This process was used for treatment of synthetic textile wastewater containing the commercial azo dyestuff Remazol Red, starch and sodium chloride. The treated textile effluent had COD lower than 18mg/l even when using initial Fenton reagents concentration as low as 1mM ferrous ions and 10mM hydrogen peroxide. The acute toxicity was higher in the biologically treated than in the untreated effluent. Photo-Fenton oxidation successfully reduced the toxicity and the final effluent was non-toxic to Artemia salina and Microtox, with the exception of the effluent containing high concentration of sodium chloride, which was moderately toxic to Microtox. For the first time the presence of algae was detected in a reactor treating textile wastewater using denaturing gradient gel electrophoresis (DGGE); bacteria and fungi were also abundant.
The results of this study suggest that using advanced oxidation after biological treatment is an effective way to degrade the organic compounds and remove toxicity from textile effluents.
The evaluation of the microbiota present during coffee wet fermentation was done in two distinct regions of Minas Gerais, Brazil: one farm in the South of Minas Gerais (Lavras=L) and another farm in ...the savannah region (Monte Carmelo=MC). The yeast population ranged from 2.48 to 4.92logCFU/g and from 2 to 4.81logCFU/g, the mesophilic bacteria population ranged from 3.83 to 8.47logCFU/g and from 5.37 to 7.36logCFU/g, and the LAB population ranged from 2.57 to 5.66logCFU/g and from 3.40 to 4.49logCFU/g in the L and MC farms, respectively. Meyerozyma caribbica and Hanseniaspora uvarum were the dominant yeasts in coffee wet fermentation at L farm, and Torulaspora delbrueckii was the dominant yeast at MC farm. The species Staphylococcus warneri and Erwinia persicina were the predominant bacteria at L farm, and Enterobacter asburiae and Leuconostoc mesenteroides were the dominant species at MC farm. Lactic acid was the principal acid detected, reaching 2.33g/kg at L farm and 1.40g/kg at MC farm by the end of the process. The volatiles composition was similar for roasted coffee from the two different regions and furans, acids, and alcohol were the main groups detected. Temporal Dominance Sensation (TDS) analyses showed that the coffee beverage from L farm was dominated by citrus and herbaceous sensory characteristics, while the coffee from MC farm was dominated by citrus, herbaceous, and nuts sensory characteristics. Evaluating the microbiota in these two regions was important in improving the knowledge of the microbial species present during coffee wet fermentation in Brazil.
•Bacteria population was more diverse than yeasts in wet coffee fermentation.•Staphylococcus warneri and Erwinia persicina were the predominant bacteria at South of Minas Gerais.•Enterobacter asburiae and Leuconostoc mesenteroides dominated the wet fermentation at savannah region.
Landfill is an important method for the treatment of municipal solid wastes. Microbes play a central role in the biodegradation and stabilization of organic matter during landfill; however, the ...succession of microbial communities in landfills and their association with organic matter still remain unclear. This study investigated the succession and diversity of microorganisms in landfill depending on different depths and ages as well as its association with dissolved organic matter (DOM) and heavy metals. The results showed that the actinobacterial diversity and richness were high compared to bacteria in young landfill cells. The diversity and richness of bacteria and actinobacterial were the highest in the middle layer in the intermediate and old landfill cells. Firmicutes, Proteobacteria, and Actinobacteria were the most dominant phyla. Firmicutes were mainly affected by the humification degree, and the aromatic and protein-like substance content of the landfill-derived DOM. The phylum Proteobacteria was greatly affected by the lipid and humic-like substances content of the landfill-derived DOM, while the distribution of Actinobacteria was regulated by both aromatic and humic-like substances. The effect of dissolved heavy metals on the microbial distribution in landfill differed for the metals Cr, Ni, Pb, Mn, Cu, Zn, and Cd. Siderophile elements (Cr, Ni, and Pb) were necessary trace elements for Proteobacteria and Actinobacteria, and promoted their growth. Oxyphilic element (Mn) was an important factor promoting the growth of Actinobacteria. However, no apparent relationship was found between sulfurophile elements (Cu, Zn, and Cd) and microorganisms.
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•The abundance of microbes in the upper and lower layers of landfills was high.•Firmicutes, Proteobacteria, and Actinobacteria were the dominant phyla in landfill.•Firmicutes played an important role in the synthesis of humic-like matter.•Proteobacteria facilitated to increase the content of aromatic compounds.•Actinobacteria could oxidize fatty chains into oxygen-containing functional groups.
•EEFBs had significant removal efficiencies of organics and nitrogen.•Microbial community structure had obvious differences between devices.•Bacteria were mainly attached on the fiber filling.•The ...majority of bacteria on plant roots were β-Proteobacteria and α-Proteobacteria.
Enhanced ecological floating beds were implemented to reduce nutrient quantity and improve the water quality of a eutrophic lake. The results showed that average removal efficiencies of CODCr, total nitrogen, NH3-N and total phosphorus for Canna indica L. set-up were 23.1%, 15.3%, 18.1% and 19.4% higher, respectively, than that of the setup with only substrate, and 14.2%, 12.8%, 7.9% and 11.9% higher than Iris pseudacorus L. ecological floating bed. The microbial community structure had obvious differences between devices and low similarity; bacteria were mainly attached on the fiber filling. The microbial population was abundant at the start and end of the experiment. Shannon index of samples selected ranged from 0.85 to 1.05. The sequencing results showed that fiber filling collected most uncultured bacteria species and the majority of bacteria on the plant roots were β-Proteobacteria and α-Proteobacteria. The co-dominant species attaching to the filling and plant was Nitrosomonadaceae.
Microbial inoculants such as
-based products are receiving great interest among researchers and agricultural producers for their potential to improve crop productivity, nutritional quality as well as ...resistance to plant pathogens/pests and numerous environmental stresses. Two greenhouse experiments were conducted to assess the effects of
-based biostimulants under suboptimal, optimal and supraoptimal levels of nitrogen (N) fertilization in two leafy vegetables: Iceberg lettuce (
L.) and rocket (
Mill.). The yield, nutritional characteristics, N uptake and mineral composition were analyzed for each vegetable crop after inoculation with
strains
(GV41) or
(T22), and results were compared to non-inoculated plants. In addition, the effect of the
-based biostimulants on microbes associated with the rhizosphere in terms of prokaryotic and eukaryotic composition and concentration using DGGE was also evaluated.
-based biostimulants, in particular GV41, positively increased lettuce and rocket yield in the unfertilized plots. The highest marketable lettuce fresh yield was recorded with either of the biostimulant inoculations when plants were supplied with optimal levels of N. The inoculation of rocket with GV41, and to a lesser degree with T22, elicited an increase in total ascorbic acid under both optimal and high N conditions.
GV41 increased N-use efficiency of lettuce, and favored the uptake of native N present in the soil of both lettuce and rocket. The positive effect of biostimulants on nutrient uptake and crop growth was species-dependent, being more marked with lettuce. The best biostimulation effects from the
treatments were observed in both crops when grown under low N availability. The
inoculation strongly influenced the composition of eukaryotic populations in the rhizosphere, in particularly exerting different effects with low N levels in comparison to the N fertilized plots. Overall, inoculations with
may be considered as a viable strategy to manage the nutrient content of leafy horticulture crops cultivated in low fertility soils, and assist vegetable growers in reducing the use of synthetic fertilizers, developing sustainable management practices to optimize N use efficiency.
Scientific research has examined the possibility of replacing fishmeal with alternative protein sources in feed for fish. The literature indicates that insects are an eco-friendly nutrient-rich ...alternative to fishmeal. The purpose of this study was to investigate the effects of including insects in a diet for rainbow trout (Oncorhynchus mykiss), by analysing organosomatic parameters, fillet yield and intestinal bacterial communities. Three experimental diets were formulated: a control diet with fishmeal as main protein source, and diets Hi25 and Hi50 where 25% and 50% of fishmeal, respectively, was replaced with partially defatted meal of larvae of Hermetia illucens (Hi; Diptera: Stratiomydae). At the end of the trial, organosomatic parameters and fillet yield were recorded. To profile the complex intestinal mucosa- and digesta-associated bacterial communities (MAB and DAB), denaturing gradient gel electrophoresis was performed on bacterial DNA extracted from intestinal mucosa and digesta, followed by sequencing of selected bands. Rainbow trout fed the alternative diets showed the same organosomatic indices and fillet yields as the control group, but increased bacterial community biodiversity, structure and composition, with ANOSIM p < .05 and p < .01 for MAB and DAB, respectively. The sequencing highlighted a clear prevalence of γ-Proteobacteria in all samples, though α- and β-Proteobacteria and Actinobacteria were also present in MAB of insect-fed fish; DAB of insect-fed fish showed a clear increase in the Firmicutes phylum compared to the control group. The results suggest that H. illucens partially defatted larva meal is a valid alternative protein source and can replace up to 50% of fishmeal in rainbow trout feed without impairing organosomatic indices nor fillet yield. The microbiological assays revealed that the intestinal bacterial communities were sensitive to dietary changes, showing modified community structure and increased biodiversity in the Hi-fed groups. We discuss the effects that modified bacterial communities could have on fish biology. There is a good possibility of further studies on the functional role of bacteria.
•Diets including 40% Hermetia illucens does not worsen r. trout fillet yield and organosomatic indices.•Intestinal bacteria communities were analysed for the first time in rainbow trout fed insects.•Community biodiversity increased in the insect-fed groups.
Abstract
Low-molecular-weight organic compounds in root exudates play a key role in plant–microorganism interactions by influencing the structure and function of soil microbial communities. Model ...exudate solutions, based on organic acids (OAs) (quinic, lactic, maleic acids) and sugars (glucose, sucrose, fructose), previously identified in the rhizosphere of Pinus radiata, were applied to soil microcosms. Root exudate compound solutions stimulated soil dehydrogenase activity and the addition of OAs increased soil pH. The structure of active bacterial communities, based on reverse-transcribed 16S rRNA gene PCR, was assessed by denaturing gradient gel electrophoresis and PhyloChip microarrays. Bacterial taxon richness was greater in all treatments than that in control soil, with a wide range of taxa (88–1043) responding positively to exudate solutions and fewer (<24) responding negatively. OAs caused significantly greater increases than sugars in the detectable richness of the soil bacterial community and larger shifts of dominant taxa. The greater response of bacteria to OAs may be due to the higher amounts of added carbon, solubilization of soil organic matter or shifts in soil pH. Our results indicate that OAs play a significant role in shaping soil bacterial communities and this may therefore have a significant impact on plant growth.
Properly conducted cocoa fermentation is an important step for the production of high-quality chocolate. The aim of this work was to investigate the effect of four cocoa varieties (CCN51, PS1030, ...FA13, and CEPEC 2004) inoculated with Saccharomyces cerevisiae CA11 on microbial communities and the profile of volatile compounds and sensory characteristics of chocolate. The S. cerevisiae population increased significantly (p<0.05) during the fermentations. The microbial communities varied according to cocoa variety fermentation as assessed by denaturing gradient gel electrophoresis (DGGE). The dominant yeasts were S. cerevisiae and Hanseniaspora guilliermondii, while Lactobacillus casei and Gluconobacter oxidans were the predominant bacteria in the four different fermentations analyzed. Sixty-one volatile compounds—including aldehydes (11), ketones (10), esters (14), acids (8), alcohols (8), pyrazines (5), furans (3), and others (caffeine and heptadecane)—were detected and quantified by GC–MS in the different chocolates. The sensory analysis showed that caramel was perceptible in the chocolate of PS1030, while CEPEC2004 was related to astringency, bitterness, and chocolate flavor attributes. The chocolates produced from FA13 and CCN51 were more similar in terms of sour and chocolate aroma. A “temporal dominance of sensation” (TDS) analysis showed that although the bitter attribute was dominant, the fruity, sweet, sour, astringent, and cocoa attributes were also perceptible, depending on the cocoa variety. These results suggest that the cocoa varieties had an influence on the chocolate's quality, which should be considered to obtain chocolate with different sensory characteristics or for better standardization of the process, even when using yeast as a starter culture.
•Chocolates were produced from different cocoa varieties inoculated with S. cerevisiae.•The microbial communities varied according to cocoa variety fermentation as assessed by DGGE analysis.•The qPCR technique was successfully used for S. cerevisiae quantification.•The S. cerevisiae population increased significantly (p<0.05) during the fermentations.•Results suggest that cocoa varieties had an influence on the chocolate's quality.
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