Aerobic granular sludge was cultivated by using di erent kinds of seed sludge in sequencing batch airlift reactor. The influence of seed sludge on physical and chemical properties of granular sludge was studied; the microbial community structure was probed by using scanning electron microscope and polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE). The results showed that seed sludge played an important role on the formation of aerobic granules. Seed sludge taken from beer wastewater treatment plant (inoculum A) was more suitable for cultivating aerobic granules than that of sludge from municipal wastewater treatment plant (inoculum B). Cultivated with inoculum A, large amount of mature granules formed after 35 days operation, its SVI reached 32.75 mL/g, and SOUR of granular sludge was beyond 1.10 mg/(g min). By contrast, it needed 56 days obtaining mature granules using inoculum B. DGGE profiles indicated that the dominant microbial species in mature granules were 18 and 11 OTU when inoculum A and B were respectively employed as seed sludge. The sequencing results suggested that dominant species in mature granules cultivated by inoculum A were Paracoccus sp., Devosia hwasunensi, Pseudoxanthomonas sp., while the dominant species were Lactococcus ra nolactis and Pseudomonas sp. in granules developed from inoculum B.

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Effect of seed sludge on characteristics and microbial community of aerobic granular sludge.

Phytoplankton are the primary producers at the basis of aquatic food webs, and bacteria play an important role in energy flow and biochemical cycling in aquatic ecosystems. In this study, both the bacterial and phytoplankton communities were examined in the oligotrophic Lake Basomtso and the eutrophic Lake South (China). The results of this study showed that the phytoplankton density and diversity in the eutrophic lake were higher than those in the oligotrophic lake. Furthermore, Chlorophyta (68%) and Cryptophyta (24%) were the dominant groups in the eutrophic lake, while Bacillariophyta (95%) dominated in the oligotrophic lake. The bacterial communities in the waters and sediments of the two lakes were mainly composed of Proteobacteria (mean of 32%), Actinobacteria (mean of 25%), Bacteroidetes (mean of 12%), and Chloroflexi (mean of 6%). Comparative analysis showed that the abundance of bacteria in the eutrophic lake was higher than that in the oligotrophic lake (p < 0.05), but the bacterial diversity in the oligotrophic lake was higher than that in the eutrophic lake (p < 0.05). Finally, the bacterial abundance and diversity in the sediments of the two lakes were higher than those in the water samples (p < 0.05), and the Latescibacteria and Nitrospinae groups were identified only in the sediments. These results suggest that both the phytoplankton and bacterial communities differed considerably between the oligotrophic lake and the eutrophic lake.

https://www.mdpi.com/2076-2607/7/12/621/pdf

Phytoplankton and Bacterial Community Structure in Two Chinese Lakes of Different Trophic Status.

To verify the dominance of microorganisms in wastewater biological treatment, PCR-DGGE (denaturing gradient gel electrophoresis) was performed as a supplementary support method for screening of the dominant microorganisms from activated sludge. Results suggest that the dominant microorganisms in activated sludge are primarily responsible for strengthening its effectiveness as a biological treatment system, followed by the non-main dominant microorganisms, whereas the non-dominant microorganisms showed no effects. The degree of microbial abundance present on the profile of PCR-DGGE was in line with the treatment efficiency of augmented activated sludge with isolated cultures, suggesting that PCR-DGGE can be used as an effective supplementary method for verifying culturable dominant microorganisms in activated sludge of coking wastewater.

PCR-DGGE as a supplemental method verifying dominance of culturable microorganisms from activated sludge.

In order to reduce incomplete fermentation caused by high substrate viscosity and low mass transfer efficiency during fermentation process, batch and two-phase anaerobic fermentation experiments were conducted in this study. Dairy manure was separated by using solid-liquid separator firstly. Separated liquid (SL) and diluted dairy manure (DDM) as raw materials were evaluated in terms of gas production performance for both batch and two-phase anaerobic fermentation. The microorganism population was characterized by scanning electron microscope (SEM) and Denaturing Gradient Gel Electrophoresis (DGGE). The results showed that Volatile Solid (VS) methane yield of SL was 124.51 L/kg VS, which was 2.09 times higher than that of DDM (59.50 L/kg VS) in batch anaerobic fermentation. The Bacteroides and Veillonella with higher activity were the majority microorganism population in acidogenic phase, whereas the Firmicutes and Corynebacterium with methanogenic properties became the predominant microorganism population in methanogenic phase. This study achieved the phase separation and improved the gas production performance.
Keywords: separated liquid, diluted dairy manure, two-phase anaerobic fermentation, microorganism, scanning electron microscope (SEM), Denaturing Gradient Gel Electrophoresis (DGGE)
DOI: 10.25165/j.ijabe.20181101.3206

Citation: Li Q, Guan Z J, Zheng G X. Microorganism population in two-phase anaerobic fermentation of separated liquid of dairy manure. Int J Agric & Biol Eng, 2018; 11(1): 206–211.

Microorganism population in two-phase anaerobic fermentation of separated liquid of dairy manure

In this study low-concentration wastewater was treated by the integral two-phase anaerobic baffled reactor, and the feasibility study of "two-phase anaerobic + aerobic" process was also discussed. Dehydrogenase activity of aerobic zone and anoxic zone was analyzed. Besides, the polymerase chain reaction and denaturing gradient gel electrophoresis (PCR-DGGE) method was used to analyze the microbial species diversity for both aerobic and anoxic zone. The result indicated that the low-concentration wastewater could be treated with high removal of organic matter, in which HRT was the key factor for COD removal. This research could provide reference value to the sewage plants in cold region for new process of wastewater treatment and sludge treatment.

Modified Anaerobic Membrane Bioreactor for Low-Concentration Wastewater Treatment

Four methanogenic granules taken from an anaerobic reactor in different periods were investigated by FISH and DGGE, the eubacterial and archaeal community in these granules was researched and the phylogenetic analysis of dominant archaea was also studied. The FISH results indicated that the quantity of eubacteria was much more than archaea in the methanogenic granule and most eubacteria were located in the out layer of granule, while most archaea were located in the inner layer. The DGGE fingerprints indicated that as the organic loading rate of the reactor increased and the operating time elapsed, the eubacterial community was kept stable relatively, while the archaeal community was changed significantly, which resulted in the gradual decrease of the archaeal varieties. As seven typical bands were cut and sequenced, the results indicated that the dominant species of archaea in granule of the last period were Methanocor pusculum, Methanobacterium, Methanosaeta, and etc.

Study on microbial community in methanogenic granular sludge by FISH and DGGE

By using a lab-scale aerated upflow sludge bed reactor, the inoculated anaerobic granule was cultivated to aerobic nitrification granule, and then converted to short-cut nitrification granule with the short-cut nitrification efficiencies above 90%. Appling real-time quantity PCR, and florescent in situ hybridization techniques, the ecological community structure of nitrification bacteria in aerobic granules were studied. The results show that there existed a layered structure in the aerobic granule, the ammonia oxidizing bacteria (AOB) was mainly located in the surface area of the granule, and the nitrite oxidizing bacteria (NOB) was mainly located in the inner area of the granule, was just adjacent to the AOB. There was no active bacteria in the inner core area. The amount of AOB in the granules increased, as the ammonia loading rate of the reactor was increased gradually. The percentage of AOB in the total amount of Eubacteria in the granule was 0.45%, 5.20%, 15.37%, 48.55% respectively, as the ammonia loading rate of the reactor were 0, 0.4, 1.0 and 2.2 kg/(m3 x d) respectively, and the nitrosofication efficiency were 0%, 35%, 50%, 99% relatively.

Yu-jiao Sun

Papers

Study on microbial community in methanogenic granular sludge by FISH and DGGE

[Community structure of nitrification bacteria in aerobic short-cut nitrification granule].