Screening of cadmium-resistant bacteria and its effect on the growth and cadmium accumulation of Pharbitis nil seedlings

doi:10.11686/cyxb2025415

Abstract

Abstract:

This study investigated the biological characteristics of Cd-resistant microorganisms and their effects on plant cadmium tolerance， providing scientific evidence for the joint microbial-plant remediation of heavy metal-polluted soils. Cd-resistant bacteria strains were isolated from polluted soil and identified using morphological， physiological， biochemical， and 16S rDNA sequence analysis. The liquid culture method was used to assess the strain’s tolerance to Cd and other heavy metals （Fe， Cu， Pb）. Fourier transform infrared （FTIR） technology was applied for characterization. The effect of the strain Hz_Cp in conjunction with Pharbitis nil on cadmium accumulation was analyzed through petri dish experiments. RT-qPCR was used to detect the expression of genes related to cadmium tolerance in P. nil. The isolated strain Hz_Cp was identified as a species of Cupriavidus， with a cadmium tolerance concentration of up to 1600 mg·L^-1. When cultured at pH 7.0 conditions， the strain removed 90.16% of cadmium. In addition to its ability to fix nitrogen， secrete indole-3-acetic acid （IAA）， and produce siderophores， this strain also displays remarkable tolerance to a range of abiotic stresses， including heavy metals， salt， and extreme temperatures. Cupriavidus sp. （Hz_Cp） bio-adsorbs cadmium ions through functional groups such as -OH， -COOH， and -PO₄^3-. P. nil was able to remove 25.34% of cadmium ions from the culture medium （reducing from 200.00 to 149.32 mg·L^-1）， and the addition of Hz_Cp significantly enhanced its cadmium tolerance. The Cupriavidus strain Hz_Cp not only significantly increased the chlorophyll， carotenoid， and anthocyanin content in P. nil but also improved peroxidase （POD） and superoxide dismutase （SOD） activities， and upregulated the expression of genes such as IpYUC1 and IpPAP1. Hz_Cp promotes the growth of P. nil seedlings under cadmium stress while reducing cadmium accumulation， demonstrating its potential for application in remediation of soil heavy metal pollution.

Key words: cadmium pollution, plant growth-promoting bacterium, Pharbitis nil, heavy metal adsorption, tolerance mechanism

Juan SONG, Gen ZHAO, Jing-han WANG, Wei GU, Jin-kai LIN, Dong-rui HONG, Li-qin ZHANG, Li-jing MIN. Screening of cadmium-resistant bacteria and its effect on the growth and cadmium accumulation of Pharbitis nil seedlings[J]. Acta Prataculturae Sinica, 2026, 35(10): 106-116.

Figures/Tables 7

References 36

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基因名 Gene name	基因功能注释 Gene function annotation	引物序列（正向引物F/反向引物R） Primer sequence （forward primer F/reverse primer R）
IpZIP2	金属离子吸收和运输功能基因Metal ion absorption and transport functional genes	GATTTGACGGAGAAGGAGTA GTTTGAAGCGTTGCCTGATG
IpPAP1	花青素生物合成Anthocyanin biosynthesis	TCTTCCATTGTGCTTTCCCTG GTTGCTGGAGTGTAGTCAGTAG
IpPOD	过氧化物酶Peroxidase	CGCCAACACTCTTTGACAACAAG ACTCATCCTTATCATTGCCTTCGC
IpYUC1	生长素生物合成Auxin biosynthesis	CAAAGAAAGGAGCAAAGTTTATGG CTGAAGCCAAGTAGGCACGTT
GAPDH	牵牛花的内参基因The endogenous reference gene for P. nil	AGCGGAAAGCCTCGCAGT TGTCGTTACCATCTCGACCCA

基因名 Gene name	基因功能注释 Gene function annotation	引物序列（正向引物F/反向引物R） Primer sequence （forward primer F/reverse primer R）
IpZIP2	金属离子吸收和运输功能基因Metal ion absorption and transport functional genes	GATTTGACGGAGAAGGAGTA GTTTGAAGCGTTGCCTGATG
IpPAP1	花青素生物合成Anthocyanin biosynthesis	TCTTCCATTGTGCTTTCCCTG GTTGCTGGAGTGTAGTCAGTAG
IpPOD	过氧化物酶Peroxidase	CGCCAACACTCTTTGACAACAAG ACTCATCCTTATCATTGCCTTCGC
IpYUC1	生长素生物合成Auxin biosynthesis	CAAAGAAAGGAGCAAAGTTTATGG CTGAAGCCAAGTAGGCACGTT
GAPDH	牵牛花的内参基因The endogenous reference gene for P. nil	AGCGGAAAGCCTCGCAGT TGTCGTTACCATCTCGACCCA

指标Indices	测定数值Measured values	指标Indices	测定数值Measured values
镉Cadmium （mg·kg^-1）	1.20±0.04	铅Lead （mg·kg^-1）	117.43±0.97
汞Mercury （mg·kg^-1）	8.58±0.10	有机质Soil organic matter （g·kg^-1）	23.85±0.16
砷Arsenic （mg·kg^-1）	7.27±0.12	全磷Total phosphorus （g·kg^-1）	0.57±0.00
锌Zinc （mg·kg^-1）	403.95±3.62	全钾Total potassium （g·kg^-1）	17.01±0.28
钙Calcium （mg·kg^-1）	204.44±2.93	速效氮Available nitrogen （g·kg^-1）	0.59±0.06
铜Copper （mg·kg^-1）	196.46±2.21

指标Indices	测定数值Measured values	指标Indices	测定数值Measured values
镉Cadmium （mg·kg^-1）	1.20±0.04	铅Lead （mg·kg^-1）	117.43±0.97
汞Mercury （mg·kg^-1）	8.58±0.10	有机质Soil organic matter （g·kg^-1）	23.85±0.16
砷Arsenic （mg·kg^-1）	7.27±0.12	全磷Total phosphorus （g·kg^-1）	0.57±0.00
锌Zinc （mg·kg^-1）	403.95±3.62	全钾Total potassium （g·kg^-1）	17.01±0.28
钙Calcium （mg·kg^-1）	204.44±2.93	速效氮Available nitrogen （g·kg^-1）	0.59±0.06
铜Copper （mg·kg^-1）	196.46±2.21

序号 Serial number	污染物项目 Pollutant items^{a， b}		风险筛选值Risk screening value
序号 Serial number	污染物项目 Pollutant items^{a， b}		pH≤5.5	5.5<pH≤6.5	6.5<pH≤7.5	pH>7.5
1	镉Cadmium	水田Paddy field	0.3	0.4	0.6	0.8
1	镉Cadmium	其他Others	0.3	0.3	0.3	0.6
2	汞Mercury	水田Paddy field	0.5	0.5	0.6	1.0
2	汞Mercury	其他Others	1.3	1.8	2.4	3.4
3	砷Arsenic	水田Paddy field	30	30	25	20
3	砷Arsenic	其他Others	40	40	30	25
4	铅Lead	水田Paddy field	80	100	140	240
4	铅Lead	其他Others	70	90	120	170
5	铬Chromium	水田Paddy field	250	250	300	350
5	铬Chromium	其他Others	150	150	200	250
6	铜Copper	果园Orchard	150	150	200	200
6	铜Copper	其他Others	50	50	100	100
7	镍Nickel		60	70	100	190
8	锌 Zinc		200	200	250	300