Microbiome, Wang Can's team, Tianjin University: The Wind Rises in Longxi: A Biofilm Regulation Strategy Based on Microbial Communication Disruption

First author: Wang Yongchao (wyc@tju.

Corresponding Author: Prof.

Communications: Tianjin University

DOI：https://doi.

Journal Name: Microbiome

Article introduction

The sum of the common characteristics of all individuals of a race, as a result of heredity, constitute the soul

--"The Ragged Crowd" Le Pen

Video guide

Research background

Controlling excess biomass accumulation and clogging is important

Article highlights

1.

2 .

3.

Graphic summary

Graphic summary

Figure 1 Effect

a.

b.

c.

When the proportion of BH4 added to erythrococcus is 10% to 50%, a pronounced dose response is observed

Figure 2.

a.
Removal efficiency
of gaseous toluene.

b.
Biomass accumulation
.

c.
Pressure drop (illustrations are the Ergun equation fitting curves for the pressure drop of BF and QQBF on days 25 and 65).

d.
Remove the load

The removal efficiency (RE) trends of BF and QQBF in the first 60 days were similar, both remaining above
80%.

With the change of running time, BF's RE gradually declined, and QQBF's RE remained stable
.

The results show that after adding BH4 to QQBF, its operational stability is significantly improved
compared with BF.

At the same time, the biomass accumulation of BF and QQBF also showed significant differences
during operation.

From day 20, the biomass accumulation of QQBF fluctuated and grew slowly, while BF increased rapidly, reaching 170 kg/m³
on day 116.

This suggests that adding BH4 to QQBF reduces biomass accumulation by 36% compared to BF
.

At the same time, the BF pressure drop increased rapidly, reaching 121 Pa/m after 60 days, while QQBF maintained a low pressure drop, only 30 Pa/m
by 120 days.

In addition, the pressure drop and flow curves
on days 25 and 65 were fitted using Ergun's equations.

The results showed that the addition of BH4 erythrococcus improved the early structure of the filter tower and maintained a low pressure drop
during operation.

Figure 3

a.
The content
of EPS in BF and QQBF biofilms throughout operation.

b.
On days 25 and 65, the adhesion strength of BF and QQBF filler surface biofilms compared
.

c.
Biofilm shedding efficiency
at the end of ultrasonic cleaning.

d.
One cycle (days 20 to 28) concentration of MLSS in BF and QQBF leachate
.

After 65 days of operation, CLSM images
of biofilms were formed e.
BF and the surface of the f.
QQBF filler.

The concentration of both protein and polysaccharides increases with the operation of BF and QQBF
.

However, at each stage, the protein and polysaccharide content of the QQBF group was lower than that of the BF group
.

The BF group (70%) and QQBF group (95%) showed significant differences in biofilm shedding efficiency on day 65 (p< 0.
05).


This suggests that the addition of BH4 inhibits the adhesion strength of QQBF biofilms compared to BF
.

Due to the regular spraying of the nutrient solution, it was found that in BF and QQBF, the MLSS concentration increased
with the increase of the operation.

Interestingly, the MLSS content in QQBF (220 mg/L) was higher than the MLSS content in BF (140 mg/L) and increased nearly 2-fold
on day 28.

Figure 4

a.
Relative abundance of the first 30 genera in BF and QQBF biofilm samples throughout the run
.

BF and QQBF biofilm samples expressed
genes with QS-related differences on days 25 and d.
90.

NMDS analysis based on Bray-Curtis distance shows differences in biofilm samples in BF and QQBF

At the initial stage of the biofiltration run (Day 25), functional genes such as K02052, K02402, and K18139 in BF were higher than QQBF
.

Conversely, some genes (K01999, K03070, K03073, etc.
) have relatively low
relative abundances in BF.

This indicates that there is no clear trend in the relative abundance of the QS gene in BF and QQBF
.

Interestingly, this phenomenon disappeared on day 90, and all but K01580 had an elevated trend
in BF for the rest of the significantly different QS genes.

This indicates that the QS gene in the QQBF biofilm is inhibited
during the long-term evolution of the biofilm.

Therefore, these results strongly suggest that the inhibition of QS activity in QQBF affects the adhesion strength of the biofilm, making it easy to separate, thereby reducing biomass accumulation and controlling clogging
.

Figure 5 Phylogenetic molecular ecological networks (pMENs)
of biofilm communities during the entire operation of BF and QQBF.

By establishing an RMT-based molecular ecology network, the ecological interactions of species in BF and QQBF biofilms were analyzed
.

These results suggest that regardless of BF and QQBF biofilms, the network of pMENs is non-random, with a small world and modular structure
.

In addition, compared with BF biofilms, the topology of the lower network node edge of QQBF biofilms is simpler
.

Interestingly, both BF and QQBF biofilms exhibit strong interspecific associations, but QQBF biofilms have high negative interactions
.

Figure 6 analyzes QS regulatory pathways
of typical QS microorganisms in BF and QQBF biofilm samples based on metagenomics.

There was no significant difference in the total amount of gene expression and the number of up- and down-regulated genes in
BF and QQBF biofilms.

At the same time, QS-related behaviors, such as biofilm formation and bacterial secretion systems, are annotated in the KEGG database as distinctly enriched differential genes
.

The results showed that the differential QS gene of typical QS microorganisms was down-regulated in QQBF biofilm, while the QS gene was not up-regulated
.

In addition, the final function of these QS pathways is related to the formation of biofilms or the synthesis of EPS, suggesting that this may be a possible way to
reduce biofilm adhesion.

Moreover, most of the downregulated QS genes are annotated as sensing proteins, suggesting that their action may occur during the sensing process
of signaling molecules.

Figure 7 Application progress of QQ technology in environmental bioreactors

Conclusion of the study

In this study, QQ bacteria (RTHCOCCAL BH4) were used to control the blockage of
waste gas biofiltration during long-term operation.

After 120 days of operation, the biomass accumulation of QQBF (added red coccal BH4) was 36%
less than that of BF.

At the same time, the pressure drop of the filter bed at QQBF is only 30 Pa/m, while at the end of the operation, the pressure drop of the filter bed is 121 Pa/m, which is also confirmed
by the Ergun equation.

In addition, due to the control of blockage, the operational stability of QQBF is significantly improved
.

Compared with BF, QQBF biofilms have lower adhesion strength and lower EPS yield, resulting in biomass more easily shedding from the filler surface into the
leachate.

In addition, through high-throughput sequencing analysis, it was found that the relative abundance of QS-related species and functional genes in QQBF was lower than that of BF
.

Through RMT-based network analysis, the role
of key species in QQBF in maintaining the stability of biofilm communities was discovered.

Finally, it was found that the functional genes of the QS pathway were inhibited, thereby reducing the secretion of EPS and the formation of biofilms, reducing the adhesion of biofilms
.

Overall, this is the first study to control biomass while maintaining stable performance (without interrupting operation) by using QQ bacteria in gas biofilters, providing new insights into
the application of clogging control and QQ technology in bioreactors.

Source: VB Control
.

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