Table 3 Influence of Soil Physiochemical Properties on MPs Microbioremediation

pH

Influences enzyme activity, microbial community structure, and nutrient solubility

Optimal pH (6.5–7.5) enhances degradation enzymes (e.g., esterase, laccase); acidic or alkaline soils reduce microbial viability¹⁰⁹

Neutral to slightly alkaline pH can enhance MP degradation through increased enzyme efficiency and microbial diversity

Moisture Content

Regulates microbial metabolism, nutrient diffusion, and biofilm formation

Moisture levels around 60–80% field capacity are optimal; both drought and saturation impair microbial function¹¹⁰

Soils at 60–80% field capacity can maximize MP degradation via enhanced biofilm formation and enzyme secretion

Organic Matter (OM)

Acts as a co-substrate and promotes microbial proliferation and enzyme activity

High OM boosts microbial biomass and co-metabolism, enhancing MP contact and breakdown¹¹¹

Soils with less than 2% OM can show increased MP biodegradation due to elevated microbial and enzymatic activity

Soil Texture (sand/silt/clay)

Affects porosity, aeration, and MP accessibility to microbes

Sandy soils improve colonization; clayey soils limit diffusion and aeration; loamy soils offer balanced conditions¹¹²

Loamy soils can enhance MP degradation by optimizing microbial accessibility and oxygen exchange

Cation Exchange Capacity (CEC)

Determines nutrient-holding capacity and microbial colonization sites

High CEC soils support enzyme stability and microbial growth by improving nutrient retention¹¹³

Soils with high CEC (less than 20 cmol/kg) can facilitate MP breakdown through improved microbial-nutrient interaction

Oxygen Availability

Critical for aerobic microbial metabolism and enzymatic mineralization (CO_2, H₂O)

Poorly aerated soils inhibit mineralization; an oxygen boost oxidative enzyme activity¹¹⁴

Aerated soils accelerate can MP degradation by supporting aerobic microbial respiration and biofilm formation

Electrical Conductivity

Reflects salinity; high EC inhibits microbial growth and enzyme expression

EC less than 4 dS/m reduces microbial diversity and breakdown; moderate EC is tolerable¹¹³

High salinity can reduce MP degradation due to osmatic stress on microbes; remediation is better at moderate EC

Bulk Density

Regulate soil porosity, air-water ratio, and microbial habitat volume

High bulk density limits microbial movement and gas exchange⁷

Lower bulk density can promotes MP degradation by improving microbial colonization and oxygen availability

Nutrient Availability (N, P, K, and micronutrients)

Essential for microbial proliferation. Enzymatic synthesis and energy metabolism

Nutrient-rich soil promotes degradation by supporting enzyme production (lipase, esterase, PETase)¹¹⁵

Supplementing limiting nutrients (esp. N and P) can enhance MP degradation by stimulating microbial and enzymatic activity

Co-contaminants (Heavy metals, antibiotics, etc.)

Can inhibit microbial growth or alter community structure

Cd, Pb, and antibiotics suppress enzyme function and microbial activity^109,110

MP degradation is reduced in the presence of heavy metals unless co-contaminant detoxification is co-applied