Rational Design and Construction of a High‑Efficiency Cadmium‑Converting <italic style="font-style: italic">Tetrahymena thermophila</italic> Strain

HU Kaikang; ZHAO Shuhui; ZHANG Jing; XIONG Jie; MIAO Wei; TU Jiawei

doi:10.12211/2096-8280.2026-038

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Rational Design and Construction of a High‑Efficiency Cadmium‑Converting Tetrahymena thermophila Strain

更新时间：2026-06-22

- Rational Design and Construction of a High‑Efficiency Cadmium‑Converting Tetrahymena thermophila Strain
- Synthetic Biology Journal Pages: 1-17(2026)
- 作者机构：
  
  1.中国科学院水生生物研究所，武汉 430072
  2.中国科学院大学，北京 100049
- 作者简介：
- 基金信息：
- DOI：10.12211/2096-8280.2026-038
  CLC： Q789
- Received：01 May 2026，
  
  Revised：2026-06-17，
  
  Online First：22 June 2026，
- 稿件说明：
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胡凯康，赵曙慧，张晶，熊杰，缪炜，涂家薇. 高效镉转化嗜热四膜虫的理性设计和构建［J］. 合成生物学， 2026， 7. DOI： 10.12211/2096-8280.2026-038

HU Kaikang， ZHAO Shuhui， ZHANG Jing， XIONG Jie， MIAO Wei， TU Jiawei. Rational Design and Construction of a High‑Efficiency Cadmium‑Converting Tetrahymena thermophila Strain［J］. Synthetic Biology Journal， 2026， 7. DOI： 10.12211/2096-8280.2026-038
胡凯康，赵曙慧，张晶，熊杰，缪炜，涂家薇. 高效镉转化嗜热四膜虫的理性设计和构建［J］. 合成生物学， 2026， 7. DOI： 10.12211/2096-8280.2026-038 DOI：

HU Kaikang， ZHAO Shuhui， ZHANG Jing， XIONG Jie， MIAO Wei， TU Jiawei. Rational Design and Construction of a High‑Efficiency Cadmium‑Converting Tetrahymena thermophila Strain［J］. Synthetic Biology Journal， 2026， 7. DOI： 10.12211/2096-8280.2026-038 DOI：

摘要

有毒金属镉（Cd）污染严重威胁生态环境与人体健康。利用微生物将镉从高生物有效性的离子态（Cd

）转化成低生物有效性的硫化物（CdS

）是减轻环境中镉污染的重要策略。近年来，环境合成生物学的发展使得基于嗜热四膜虫（

Tetrahymena thermophila

）等特色底盘生物构建镉污染修复体系成为可能。本研究通过对嗜热四膜虫镉感知、结合与转化三个功能模块的理性设计，构建了高效的镉转化嗜热四膜虫。在感知方面，利用

MTT1

基因的镉诱导启动子（pMTT1）作为镉响应传感器，驱动下游功能基因在镉胁迫下的过表达。在结合方面，通过敲降内源性 MTT1解除对胞内 Cd

的结合，释放Cd

作为转化底物。在转化方面，通过同源重组将

MTT1

编码区置换为反向转硫途径关键酶基因

TtCBS1

，增强半胱氨酸合成与内源性H

S生成，加速 Cd

向低毒、稳定的 CdS 转化。该设计通过基因改造，同步实现了镉感知响应、结合解除与转化增强。所得工程株EC

较

MTT1

敲降株提升252.6%。在5 mg/L Cd

处理下，24 h Cd

镉去除率和转化率分别高达94.7%和91.6%。本研究构建的高效镉转化嗜热四膜虫为基于微生物的镉污染修复提供了新策略。

Abstract

Toxic metal cadmium (Cd) pollution poses a serious threat to ecological environments and human health

and efficient

green bioremediation technologies are therefore urgently needed. The construction of efficient cadmium biomineralization systems via synthetic biology is regarded as an important direction for future Cd remediation.

Tetrahymena thermophila

can be easily cultured

its genetic manipulation is well-established

and it is naturally endowed with the capacities for Cd sensing

accumulation

and conversion. Cd

can be efficiently removed from water

accumulated intracellularly

and converted into less toxic CdS. Consequently

T. thermophila

can be used as a synthetic biology chassis for the construction of "Cd-conversion" cell strains. To construct a high‑efficiency cadmium biomineralization system based on this chassis

the functions and efficiencies of its key genes involved in cadmium mineralization must first be evaluated

after which rational design can be conducted accordingly. In this study

the functions of three key genes involved in Cd

conversion during Cd

removal and transformation by

T. thermophila

were examined

namely

MTT1

encoding the cadmium-binding protein metallothionein

TtCSA1

encodin

g cysteine synthase (a key enzyme in the de novo cysteine biosynthesis pathway)

and

TtCBS1

encoding cystathionine-β-synthase (a key enzyme in the reverse transsulfuration pathway). The results showed that although the Cd

tolerance (EC

) of the cells was reduced by 74.8% by

MTT1

knockdown

the Cd

removal rate and conversion rate were significantly enhanced (reaching as high as 98.7% and 88.1%

respectively

at 5 mg/L Cd

). The reason may be that after the binding of MTT1 protein to Cd

is relieved

the bound Cd

is released and then enters the CdS conversion process as a reaction substrate. Cd

removal was not affected by knockdown or knockout of

TtCBS1

and

TtCSA1

but CdS conversion efficiency was significantly decreased

with a greater reduction being observed for

TtCBS1

(13.8%) than for

TtCSA1

(5.4%) relative to the wild type. Based on these findings

the

MTT1

coding region was replaced with

TtCBS1

TtCSA1

via homologous recombination

so that endogenous

MTT1

was knocked down while overexpression of

TtCBS1

TtCSA1

was concurrently achieved

and "Cd-conversion" cell strains based on the

T. thermophila

synthetic biology chassis were constructed. Among them

the EC

of the

MTT1

knockdown combined with

TtCBS1

overexpression strain was increased by 252.6% compared with the

MTT1

knockdown strain

and a conversion rate of up to 91.6% could be reached at 5 mg/L Cd

. Through a single genetic modification

sensing response

substrate release

and conversion enhancement were simultaneously achieved by this design

and a cell strain with high efficiency in removing and converting Cd

from water was ultimately obtain

ed. The feasibility of

T. thermophila

as a programmable chassis for toxic metal remediation is validated in this study

and a new strategy for synthetic biology-driven environmental bioremediation is provided.

关键词

Keywords

references

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⁰

Rational Design and Construction of a High‑Efficiency Cadmium‑Converting Tetrahymena thermophila Strain

DOI：10.12211/2096-8280.2026-038

摘要

Abstract

关键词

Keywords

references