Get Permission Lazer, Arun K S, Mathew, Chandran, Jomol P J, and Vijayan: The application and assessment of bacterial isolates for textile dye decolorization


Introduction   

The global textile industry is expansive, contributing significantly to environmental pollution due to its heavy reliance on synthetic dyes for coloring.1 Annually, around 30 million tonnes of textiles are produced worldwide, requiring about 700,000 tonnes of various dyes.2 These dyes, containing chromophore groups, bind to materials to impart color. Among them, azo dyes are particularly notable for their durability and resistance to degradation,3 finding applications in textiles, rubber products, color photography, paper printing, pharmaceuticals, cosmetics, and food processing.

Textile industry effluents present significant treatment challenges due to their high chemical oxygen demand (COD), biological oxygen demand (BOD), elevated temperatures, intense coloration, variable pH levels, and the presence of metal ions.4 Approximately 10-15% of dyes are lost during dyeing processes, and traditional textile finishing consumes about 100 liters of water per kilogram of textile material processed.5 Despite being cost-effective and easy to synthesize,6 azo dyes pose considerable health and environmental risks due to their toxicity, carcinogenicity, and mutagenicity.7 Their resistant azo bonds hinder breakdown, leading to persistence and potential accumulation in the environment.8

The increasing need for potable water and its decreasing availability underscore the importance of treating and reusing industrial effluents.9 Colored effluents, especially those from industrial sources, reduce light penetration and gas solubility in water bodies, impairing photosynthesis in phytoplankton and posing aesthetic concerns.10, 11 Azo dyes and their breakdown products, such as aromatic amines, are known carcinogens and mutagens.12, 13, contributing to health risks like bladder cancer and hepatocarcinoma. 14 In soil, high dye concentrations inhibit seed germination, stunt plant growth, and suppress the elongation of shoots and roots.

Physicochemical methods for treating colored textile effluents are often expensive and generate substantial sludge, leading to further pollution.15 As a result, the economical and safe disposal of pollutant dyes remains a critical issue.16, 17 Microorganisms, including bacteria, fungi, and yeast, have shown diverse capabilities in decolorizing various dyes, although the degradation of dye molecules can be slow, allowing for persistence and accumulation. Bioremediation, using microorganisms,18, 19 offers a financially viable and environmentally friendly alternative for managing textile effluents by biologically breaking down or converting hazardous chemicals into less harmful forms.20, 21 Compared to physicochemical methods, biological processes are favored for their cost-effectiveness, minimal sludge formation, and environmental compatibility.22, 23

Materials and Methods

The wastewater sample containing textile dyes was obtained from a dyeing industry in Nemam, Thiruvananthapuram, Kerala. Three types of dyes—direct black, blue, and orange—were selected for this study.

Physical analysis of samples

The samples were assessed for color and odor characteristics upon collection. Dilutions were prepared and spread onto nutrient agar plates, then incubated at 37°C for 24 hours to enumerate bacterial counts.

Characterization of bacterial strains

Characterization involved macroscopic and microscopic observations, biochemical tests, and molecular methods.

Decolorization activity assay

Commercial dyes (direct orange, direct blue, and direct black) were used in the decolorization study. Nutrient broth containing 0.1 g of dye per 100 ml was inoculated with 1 ml of each isolated test organism and incubated at 37°C for 1-3 days. Decolorization percentages were determined using a colorimeter before and after incubation, referencing control samples.

Impact of dye strength on decolorization

Dyes were tested at concentrations of 100 mg/L, 200 mg/L, 300 mg/L, and 400 mg/L in separate test tubes. Each tube was inoculated with 1 ml of isolated test organisms, and decolorization rates were measured colorimetrically.

Influence of pH on dye decolorization

Dyes were adjusted to pH levels of 5, 6, 7, 8, and 9, and inoculated with 1 ml of each isolated test organism. Decolorization efficiencies were assessed after incubation, with absorbance readings taken using a colorimeter.

Impact of temperature on dye decolorization

Dyes were exposed to temperatures of 28°C, 37°C, and 40°C in test tubes inoculated with 1 ml of each isolated test organism. Decolorization rates were determined using absorbance measurements.

Seed germination test

The impact of dyes on soil was evaluated by germinating Setaria italica seeds in sterile plastic dishes filled with fertilized soil. Three dishes were prepared: one with textile dye (10000 ppm), one with test organism AZ2 (10000 ppm), and a control dish with only soil. After six days at room temperature (28±2°C), shoot and root lengths of the seedlings were measured.

16S rRNA sequences analysis

DNA from the bacterial isolate AZ2 was prepared and amplified via PCR using specific primers. Sequencing was performed and analyzed for identification and characterization purposes.

Results

The wastewater sample from the textile industry exhibited a dark black color and strong odor, with a pH of 8, indicating alkalinity (Table 1, Table 2). A diverse array of microbes was cultured on nutrient agar plates, characterized by distinct colony traits such as shape, size, color, elevation, and transparency(Table 3 &4). Three bacterial isolates—designated AZ1, AZ2, and AZ3—were selected for further analysis.

Bacillus sp., Micrococcus luteus, and Pseudomonas sp. were identified among the bacterial isolates. The efficiency of these isolates in decolorizing direct blue, black, and orange dyes at concentrations around 1000 ppm was assessed (Table 5). The isolates were incubated under agitation, and color changes were noted after 24 hours. Bacillus sp. exhibited the highest average decolorization at 200 mg/L, Micrococcus luteus at 400 mg/L, and Pseudomonas sp. at 100 mg/L.

The influence of pH on decolorization was tested across pH levels 5, 6, 7, 8, and 9. Bacillus sp. showed optimal decolorization at pH 8, while Micrococcus luteus and Pseudomonas sp. showed highest efficiencies at pH 7. The impact of temperature on decolorization was studied at 28°C, 37°C, and 40°C, revealing that Bacillus sp. achieved peak decolorization at 37°C, while Micrococcus luteus and Pseudomonas sp. exhibited maximum efficiencies at 40°C.

The toxicity of the dyes was assessed by studying their impact on seed germination, plant shoot growth, and root elongation (Table 6). Results indicated that higher dye concentrations were more detrimental to seed germination. The interaction of these dyes with selected bacterial strains correlated with observable changes in plant growth, using Setaria italica seeds as the test plant.

Identification of Species

The identified organism AZ2 was “Micrococcus luteus strain JW-22” (Figure 1). The PCR primers designed for analyzing the 16S rRNA sequence were:

Forward primer: 5’-TGTACACACCGCCCGTC-3’

Reverse primer: 3’-CTCTGTGTGCCTAGGTATCC-5’

Table 1

Showing physical analysis of textile waste water

S.No.

Parameter

Results

I.

pH

8

II.

Colour

Dark black

III.

Colour intensity

0.600

IV.

Odour

Pungent smell

Table 2

Showing microbial volume of textile wastewate

Sample

Dilution

Bacterial count (CFU/ml)

Textile waste water sample

10-2

TLTC

10-3

TLTC

10-4

TLTC

10-5

TLTC

10-6

TLTC

10-7

TLTC

Table 3

Showing the structural features of the bacterial isolates

S. No

Bacterial isolates

Growth on plates

Colour

Elevation

Transparency

Shape

Size

1.

AZ1

White

Flat

Opaque

Irregular

Large

2.

AZ2

Cream

Convex

transparent

Circular

Small

3.

AZ3

Dissusible green

Umbonate

Transparent

Oval

medium

Table 4

Showing microscopic characterization of bacterial isolates

S. No.

Biochemical, physiological and selective plating

Bacterial isolates

AZ1

AZ2

AZ3

1.

Gram’s staining

G positive rod

G negative, cocci

G negative rod

2.

Motility

Positive

Negative

Positive

3.

Spore staining

Positive

Negative

Negative

4.

Indole

Positive

Negative

Negative

5.

Methyl red

Negative

Negative

Negative

6.

Voges proskaur

Negative

Negative

Negative

7.

Citrate utilization

Positive

Positive

Positive

8.

TSI test

A/AL

A/AL, gas

A/AL

9.

Catalase test

Positive

Positive

Positive

10.

Oxidase test

Positive

Positive

Positive

11.

Urease

Positive

Positive

Positive

12.

Nitrate

Positive

Negative

Positive

13.

Casein

Positive

Positive

Positive

14.

Gelatine

Positive

Negative

Positive

15.

starch

Positive

Negative

Negative

16.

Lipid

Positive

Negative

Positive

17.

Carbohydrate

Positive

Positive

Positive

18.

Bacterial growth on selective medium

Bacilluscereus agar

Tripticasesoy agar

Cetrimide agar

19.

Isolates obtained

Bacillus

Microccocus

Pseudomanas

Table 5

Showing impact of dye strength on decolorization

Isolate

Colour of dye

Decolourization Percentage (%)

100 milligrams per liter

200 milligrams per liter

300 milligrams per liter

400 milligrams per liter

500 milligrams per liter

AZ1

Blue

82

86

51

39

36

Black

11

14

21

28

28

Orange

82

84

85

85

87

AZ2

Blue

33

37

57

63

60

Black

96

95

88

85

71

Orange

88

88

89

93

97

AZ3

Blue

16

17

25

16

19

Black

70

80

53

64

58

Orange

66

49

57

22

20

Table 6

Bioassay for dye toxicity (Seed Germination Test)

S. No

Soil type

Length of shoot(cm)

Length of root (cm)

1.

Fertile soil

3.8

1.5

2.

Soil+dye

1

0.3

3.

Soil+dye+organism

3

0.5

Figure 1

Showing Electrophotogram of the sample Micrococcus luteu

https://typeset-prod-media-server.s3.amazonaws.com/article_uploads/401572f9-41bb-46e9-906b-db914088001c/image/a568009a-7fa7-4118-8e44-e5796c4c9207-uimage.png

Discussion

Textile wastewater has significantly contributed to soil pollution. In this study, Micrococcus luteus exhibited the highest decolorization efficiency under optimal conditions of pH 7 and a temperature of 40°C. Previous studiesof Saratale et al., (2009) have demonstrated similar results, with optimal decolorization occurring at pH levels ranging from 6 to 8 and temperatures around 37°C.24 The biological activities of these organisms are influenced by pH, which affects dye molecule movement through cell membranes, a critical step in decolorization kinetics. Temperature is also crucial for microbial growth and enzymatic activity.6

The selected organisms in this study showed rapid decolorization rates, achieving nearly 100% color removal within one day of incubation. No phytotoxic effects were observed at the tested dye concentrations, suggesting the potential of effluent-derived isolates in efficient dye degradation. Textile dye pollution poses significant threats to soil and water quality, necessitating the conversion of toxic dyes into non-toxic forms before discharge into the environment.25, 26 The isolates examined in this study show promise in decolorizing commonly used textile dyes and could serve as effective tools for bioremediation strategies, enabling the safe reuse of effluents within the textile industry.

Conclusion

This study demonstrates the significant potential of bacterial isolates, particularly Micrococcus luteus, in bioremediating textile dye pollution. Micrococcus luteus achieved maximum decolorization within one day at an optimum pH of 7 and temperature of 40°C, aligning with previous research on the efficacy of similar conditions. The study underscores the critical role of pH and temperature in enhancing microbial growth and enzyme activity, essential for effective dye decolorization. The bacterial isolates from textile wastewater showed rapid decolorization, achieving almost 100% color removal without causing phytotoxicity, as evidenced by healthy plant germination and growth in both dye-exposed and control groups. These findings suggest that the tested isolates could be valuable tools for bioremediating textile effluents, converting toxic dyes into non-toxic, colorless products, and facilitating the reuse of treated effluents in the textile industry, thus offering a sustainable solution for managing textile wastewater pollution.

Source of Funding

None

Conflict of Interest

None.

References

1 

MP Prasad P Bhakat S Chatterjee Optimization of textile dye degradation by bacterial species isolated from natural sourcesJ Ecol Environ Sci20134979

2 

M Sudha . A Saranya G Selvakumar N Sivakumar Microbial degradation of Azo Dyes: A reviewInt J Curr Microbiol Appl Sci2014367090

3 

U Aftab R K Muhammad M Muhammad A Musadiq H A Salik A Rehman Decolourization and degradation of textile azo dyes by Corynebacterium sp. isolated from industrial effluentPak J Zool201143118

4 

W Azmi RK Sani UC Banjaerjee Biodegradation of triphenyl Methene dyeEnzyme Microb Technol199822318591

5 

T Marimuthu S Rajendran M Manivannan Decolourisation of reactive textile dye effluent by using Bacterial strainInt J Sci Eng Res20134164656

6 

S Kumar T Muruganandham V Kathiravan R Ravikumar MSM Jabbir Rapid decolourization of Disperse Red F3B by Enterococcus faecalis and its Phytotoxic EvaluationInt J Curr Microbiol Appl Sci201325267

7 

F Elisangela Z Andrea DG Fabio RM Cristianao DL Regina CP Artur Biodegadation of textile azo dyes a faculatative Staphylococcus arlettae starin VN-11 using sequential Microaerophilic and aerobic processInt Biodeterioration Biodegradation2009632808

8 

S Khan N Mathur Biodegradation of Different Dye by Bacterial Strains Isolated from Textile Effluents of Western Rajasthan, IndiInt J Curr Microbiol Appl Sci201549941001

9 

MN Bayoumi RS Al-Wasify SR Hamed Bioremediation of Textile Wastewater Dyes using Local Bacterial IsolatesInt J Curr Microbiol Appl Sci201435765

10 

C Cripps JA Bumpus SD Aust Biodegradation of azoand heterocyclic dyes by Phanerochaete chrysosporiumAppl Environ Microbiol19905611148

11 

MC Thakur Arifkhan H Dosbi Isolation and screening of dye degrading microorganisms from the effluents of dye and textile industries at SuratJ Environ Eng201261529

12 

RG Saratale GD Saratale DC Kalyani JS Chang SP Govindwar Enhanced decolorization and biodegradation of textile azo dye Scarlet R by using developed microbial consortium-GRBioresour Technol200910092493500

13 

IL Ehency S Rajan AR Murugesan R Rajesh B Elayarajah Biodegradation of Textile azo dyes and its bioremediation potential using seed germination efficiencyInt J Curr Microbiol Appl Sci201310496505

14 

S Saranaik P Kanekar Bioremediation of colour of methyl violet and phenol from a dye industry waste effluent using Pseudomonas sp. Isolated from factory soilJ Appl Bacteriol19957945969

15 

S Kannan . K Dhandayuthapani Mazher Sultana Decolourization and degradation of Azo dye - Remazol Black B by newly isolated Pseudomonas putidaInt J Curr Microbiol Appl Sci2013210816

16 

S Jaiswal AV Gomashe S Agrawal Decolourization potential of Bacillus sp. for removal of synthetic textile dyesInt J Curr Microbiol Appl Sci20143838

17 

OD Olukanni AA Osuntoki GO Gbenle Decolourization of Azo Dyes by a Strain of Micrococcus Isolated from a Refuse Dump SoilBiotechnology200984428

18 

AA Durve AR Gupta SR Naphade Decolourisation of Textile Dyes and Biological stains by Bacterial strains isolated from Industrial effluentsAdv Appl Sci Res20123266071

19 

GP Srinivasan A Sikkanthar A Elamaran CR Delma K Subramaniyan S Thirugnanasambandan Biodegradation of carcinogenic textile azo dyes using bacterial isolates of mangrove sedimentJ Coastal Life Med201415462

20 

U Meyer T Leisinger AM Cook R Hutter J Nuesch Microbial degradation of xenobiotic and recalcitrant compoundsFEMS Symposium19811237185

21 

JR Sowparnika V Balakrishnan Ecofriendly approach of textile dye effluent decolorization by using microbial sourceInt J Curr Microbiol Appl Sci201331929

22 

M Gurulakshmi DNP Sudarmani R Venba iodegradation of Leather Acid dye by Bacillus subtilisJ Adv Biotechnol20087128

23 

MM Hassan MZ Alam MN Anwar Biodegradation of Textile Azo Dyes by Bacteria Isolated from Dyeing Industry EffluentInt Res J Biol Sci201322731

24 

A Karthikeyan N Anbusaravanan Isolation, identification and characterisation of dye- Adapted bacteria from textile effluents mixed with sewage released into the river AmaravathyIOSR J Environ Sci, Toxicol Food Technol20137517

25 

H Zollinger Color Chemistry- Synthesis, properties and application of organic dyes and pigmentsVCH PublishersNew York198792100

26 

RJ Pandit B Patel PD Kunjadia A Nagee Isolation, characterization and molecular identification of heavy metal resistant bacteria from industrial effluent, Amla-khadi-Anhleshwar, GujaratInt J Enviorn Sci2013316899



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Received : 14-06-2024

Accepted : 17-08-2024


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https://doi.org/10.18231/j.ijmr.2024.035


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