Microbial Biosurfactant Screening: Diversity in Assessment Methods

Simple to use

Gives indication of biosurfactant presence

Low stability of emulsion

Surface activity and emulsification capacity do not always correlate

Precise

Simple

Reliable

Concurrent measurements present difficulties

Variation prone

High precision

Small sample volume

Low quantity of biosurfactant detected

No need for specialized equipment

Rapid

Amount of oil used influences detection

Simple

Rapid

No need for specialized equipment

Small sample volume

Low sensitivity

Used for screening large number of samples

Qualitative

Easy

Rapid

Sensitive

Small sample volume

Suitable for automated high throughput screening

Rough

Only qualitative

Simple

Inexpensive

Indirect

Only qualitative

Simple

Easy

Preliminary

If negligible amount of surfactant is present, false results are given

Direct

Efficient

Cannot be used if microbe does not degrade hydrocarbons

Surface enhanced biosurfactant production is shown

Many strains only produce biosurfactant in liquid media

Preliminary screening method

Also predicts surface activity of producer

Dubious results (lytic enzymes can also cause hemolysis)

Hydrophobic substrates cannot be used as sole carbon source

Diffusion restriction can inhibit zone formation

Semi-quantitative

Allows various culture conditions

Specific for anionic biosurfactants

Inhibits growth of some microbes