Feather keratin hydrolysates obtained from microbial keratinases: effect on hair fiber

Abstract

Background: Hair is composed mainly of keratin protein and a small amount of lipid. Protein hydrolysates, in particular those with low molecular weight distribution have been known to protect hair against chemical and environmental damage. Many types of protein hydrolysates from plants and animals have been used in hair and personal care such as keratin hydrolysates obtained from nails, horns and wool. Most of these hydrolysates are obtained by chemical hydrolysis and hydrothermal methods, but recently hydrolyzed hair keratin, feather keratin peptides, and feather meal peptides have been obtained by enzymatic hydrolysis using Bacillus spp in submerged fermentation.

Results: Keratin peptides were obtained by enzymatic hydrolysis of keratinases using Bacillus subtilis AMR. The microorganism was grown on a feather medium, pH 8.0 (1% feathers) and supplemented with 0.01% of yeast extract, for 5 days, at 28°C with agitation. The supernatant containing the hydrolysates was colleted by centrifugation and ultra filtered in an AMICON system using nano-membranes (Millipore - YC05). The Proteins and peptides were analyzed using HPTLC and MALDI-TOF-MS. Commercial preparations of keratin hydrolysates were used as a comparative standard. After five days the feather had been degraded (90-95%) by the peptidases and keratinases of the microorganism. MALDI-TOF mass spectrometry showed multiple peaks that correspond to peptides in the range of 800 to 1079 Daltons and the commercial hydrolysate was in the range of 900 to 1400 Da. HPTLC showed lower molecular mass peptides and amino acids in the enzymatic hydrolysate when compared with the commercial hydrolysate . A mild shampoo and a rinse off conditioner were formulated with the enzymatic hydrolysate and applied to hair fibers to evaluate the hydration, with and without heat, using a Corneometer® CM 825. The hydration was more efficient with heat, suggesting a more complete incorporation of hydrolysates into the fibers. Scanning Electron Microscopy showed deposits of organic matter in the junction of the cuticles that probably collaborates to the sealing of the cuticles, increasing the brightness and softness.

Conclusions: These results show that the enzymatic method to produce keratin peptides for hair care products is an attractive and eco- friendly method with a great potential in the cosmetic industry.

Figure 1

Hair structure.

Figure 2

Flowchart to apply enzymatic hydrolysates on hair.

Figure 3

A Control: Bacillus subtilis in feather containing medium (time 0) and B After 5 days of growth in feather medium.

Figure 4

MALDI-TOF MS analysis of the enzymatic keratin hydrolysates from feather keratin by Bacillus subitilis (A) and a commercial hydrolysate (KH1) (B). For details see Materials and Methods.

Figure 5

HPTLC analysis of keratin peptides after filtration by ultrafiltration in the Amicon system (Millipore, 1000 Daltons). 1 - Amino acid glycine. 2 - Feather keratin peptides obtained by enzymatic hydrolysis. 3 - Commercial hydrolysate (KH1).

Figure 6

Scanning electron microscopy (SEM) analysis of colored hair A, B –Control; C, D - After the treatment with the enzymatic hydrolysates and straightener at 180°; E, F- After the treatment with the enzymatic hydrolysates without heat. Arrows indicate feather enzymatic hydrolysate deposits.

Figure 7

SEM Micrography analysis of colored and straightened hair after enzymatic hydrolysate treatment. Treated hair A, B - Control; C, D- After treatment with the enzymatic hydrolysates and straightener at 180°; E, F- After treatment with the enzymatic hydrolysates without heat, Note the deposit of the enzymatic hydrolysates on the scales (arrow).

Figure 8

Electronic scanning microscope images obtained from an untreated bleached hair (A, B) and treated with the enzymatic hydrolysates with heat (C,D) or without heat (E,F). Black arrow indicates deposit of peptides from the enzymatic hydrolysates and white arrow shows the broken edges of the cuticle.