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4 Bioremediation of Toxic Dyes for Zero Waste

Table 4.3

Competitive advantages of bacteria for the degradation of azo dyes.

Sl. no.

Identified bacteria

Advantages

1.

Aerococcus sp., Carnobacterium sp.,

Enterococcus sp., Lactobacillus sp.,

Lactococcus sp., Pediococcus sp.,

Streptococcus sp., and Weissella sp.

To carry out their metabolic

activities, they use complex organic

compounds

2.

Proteus vulgaris

They have short life cycles, creating

faster processes of discoloration

3.

Staphylococcus equorum and

Psychrobacter alimentarius

When used in consortiums, their

degradation ability is enhanced

4.

Escherichia coli, Klebsiella aerogenes,

firmicutes sp., Staphylococcus aureus,

Pseudomonas putida, Bacillus sp.,

Streptomyces sp., and Arthrobacter

viscosus

Heavy metal resistance is identical to

the mechanisms of antimicrobial

resistance

5.

Bacillus sp., Proteus mirabilis, Aeromonas

hydrophila, Pseudomonas sp., Escherichia

coli, and Klebsiella sp.

They have a higher rate of growth

and adaptability

6.

Bacillus sp., Aeromonas hydrophila,

Proteus mirabilis, and Pseudomonas sp.

Their use is more natural,

cost-effective, and ecological

7.

Aeromonas hydrophila

They degrade anaerobic

degradation-generated aromatic

amines

8.

Micrococcus glutamicus, Pseudomonas sp.,

Enterococcus gallinarum, Klebsiella sp.,

Lysinibacillus sp., and Micrococcus sp.

The efficacy of the degradation of

dyes has to do with the existence of

enzymatic genes that, in the

presence of toxic substances, can be

expressed or over-expressed in an

innate way

Source: Paba et al. [12]. Licensed under CC BY 4.0.

activity. By giving the bacterial culture an optimum temperature that is typically

stated as 30–40 ^∘C for most bacteria, a faster rate of dye degradation can be achieved.

There are, however, few thermophilic bacteria recorded for high-temperature azo

dye degradation. It has been reported that the thermophilic bacteria Anoxybacillus

rupiensis could degrade 75% effluent at 60 ^∘C [17].

Structure of Dyes The decolorization potential of bacteria is greatly affected by varia-

tions in the chemical structures of the azo dyes. Studies have shown that it is easy to

decolorize the low molecular weight and basic structure containing dyes. Whereas

there is a low decolorization rate of high molecular weight and complex structure

containing dyes. Azo compounds containing hydroxyl or amino groups are more

vulnerable to degradation than those containing other functional groups. Likewise,

as compared to diazo and triazo dyes with high molecular weight, bacteria decol-

orize monoazo dyes quicker. Owing to their inability to travel through the bacterial

cell membrane quickly, sulfonated azo dyes are thought to be more recalcitrant than