Test 4 -Time Course Analysis

To study the inhibitory effect of bamboo, rayon and cotton & 50/50% bam/cot samples towards microorganism

The inhibitory effect of bamboo, cotton, rayon and 50/50% bam/cot samples towards bacteria (E. coli and S. aureus) and fungi (T. viridae and A. niger) were compared based on a time course analysis and it was observed that E. coli was able to survive, only up to 24 hours on bamboo and 50/50% bam/cot whereas on rayon it was able to survive for up to 120 hours. It was also observed that E.coli was able to survive for up to 72 hours on 100% cotton. It was also observed that S. aureus was able to survive on bamboo up to 48 hours and 50/50% bam/cot whereas on 100% cotton it was able to survive for up to 72 hours. It was also observed that S. aureus was able to survive on rayon up to 120 hours.

Test 5 - Other Normal Validation Tests

AATCC standard tests such as AATCC 100, AATCC 147, AATCC 30 and soil burial test, were carried out. All the above tests confirmed that the antimicrobial effect was highest in the case of bamboo followed by 50/50% bam/cot, rayon and cotton. Odour evaluation test was also carried out.

Soil Burial Test

The samples were buried in the microbial active soil at 1-3cm depth. After incubation at room temperature, the samples were removed and washed thoroughly of soil particles and examined for degradation.

Table 8 Soil burial test of different samples

Odour Inhibition Test

Tests for odour inhibition are done with a bottle incubation method using an artificial perspiration consisting of sodium chloride (2.5%), urea (1.2%) and lactic acid 85% (3.4%), potassium hydroxide (1.4%) and pH adjusted to 7.0 with ammonium hydroxide. This solution is incubated with soil suspension (1gm garden soil to 10ml water, 1 ml suspension to 100ml artificial perspiration). The sample is incubated in 500ml stoppered jar at 30^oC. The odour is judged subjectively by assessers after 1, 4, 8 and 11 days.

Table -9 Assessment of odour property

Conclusion

Based on the above in-depth analysis, it was observed that bamboo has GOOD antimicrobial properties followed by 50/50% bam/cot, cotton and rayon. The various tests carried out namely, rate of growth, survivability of bacteria and fungi, time course analysis of the inhibitory effect against microbes, normal AATCC procedures like AATCC 30, AATCC 100, AATCC 147 and Soil burial test confirm that the antimicrobial effect of bamboo samples is comparatively of an higher order than 50/50% bam/cot, cotton and rayon. Results also show that there is no appreciable level of antimicrobial activity for cotton samples and it supports the growth of micro-organisms on it. In the highlight of above in-depth study and its findings, it is evident that bamboo samples have got indigenous antimicrobial effect. This indigenous anti microbial property of bamboo makes it more suitable for clothings such as inner wears & foot wears such as socks as compared to cotton.