Bugs in the Closet

Source: The Hitavada      Date: 14 Nov 2017 13:14:24

CLOTHES are one of the basic requirements of humans. With clothes comes dirt, sweat and odour. Everyone of us have been scolded for smelly clothes, some or the other day in our life. We are always lectured and bombarded about personal hygiene, managing body odour and keeping our clothes odourless and clean. But have you ever wondered why odour is generated and what actually is it? Let’s try to find out.

Odour is an unpleasant smell emitted from our body and clothes. Odour is caused due to the conversion of particular substances present in our sweat to volatile substances by the bacteria present on our skin. Chemically odours are steroids, volatile fatty acids (VFAs) or Thioalcohols. The micro-organisms responsible for the formation of these odours are Micrococcaceae spp, Corynebacterium spp, Propionibacterium spp, Staphylococci spp and many other organisms. Corynebacterium spp and Micrococcus spp are the most important odour causing organisms. But this happens only when there is over growth of these organisms under certain conditions. From the above information it is clear that bacteria present on our skin are responsible for the formation of odours . But does formation of odour has some relation with the type of fabric/textiles also ?Yes, it does.

Vast variety of organisms are present on our skin also clothes are in continuous contact with our skin. Due to which the bacteria present on our skin gets transferred on the clothes. Sweat is also responsible for this transfer of bacteria form skin to clothes. This transfer also depends on other factors like temperature, humidity, gender, immunity and use of cosmetics by the individual .

Clothes absorb moisture from skin, this gives rise to high humid conditions. High humid conditions provide favourable environment for the growth of bacteria, also sweat adds to the favourable conditions by providing nutrition to these bacteria. Odours are created when bacteria digest the nutrients present in our sweat and releases volatile and pungent waste products. But this growth of bacteria and odour production largely depends on the nature of the clothing material. Fabrics are of two types, natural and synthetic. Natural fabrics include cotton and other cellulose based materials, e.g. Jute. Polyester, Polypropylene, Polyamide, Nylon are the most commonly used synthetic fabrics.

Bacteria like Micrococcus leuteus, Staphylococcus spp, Propionibacterium, Enhydrobacter spp specifically grew on synthetic fabrics. But Micrococcus was found in the highest number on synthetic fabrics. Nylon fabrics provided a very good environment for the growth of Propionibacterium spp, Staphylococcus and Enhydrobacter spp. But nylon fabrics inhibited the growth of bacteria Micrococcus spp and Corynebacterium spp.

Staphylococcus hominis is predominantly found on cotton fabrics. Other organisms like Propionibacterium and Enhydrobbacter spp was also found cotton fabrics. In a recent research it was found that, growth of bacteria on natural fabrics was less as compared to synthetic fabrics. This was due to lower absorption of sweat by synthetic fabrics due to which sweat remains on the fabric surface and creates high humid conditions. This high humidity promotes growth of bacteria. It was found that Synthetic fabrics create high malodour compared to cotton fabrics.

This is because cotton absorbs sweat and moisture more effectively, this also results in odorous compounds being absorbed and not getting emitted. Also growth of bacteria on Synthetic and cotton fabrics is different.Corynebacterium spp and Micrococcus spp are the most important odour causing organisms.Synthetic fabrics showed specific and high growth of Micrococcus spp, this causes the fabrics to smell bad also less absorption of sweat and moisture adds to the malodour.

On the other hand cotton fabrics stop or inhibit the growth of bacteria like Corynebacterium spp and Micrococcus spp. Cotton fabrics are good at absorbing sweat, moisture and malodour.This is the reason why synthetic fabrics emit more odour as compared to cotton fabrics. But synthetic fabrics like viscose shows very less growth of odour producing bacteria . Nylon fabrics can inhibit the growth of Micrococcus spp and Corynebacterium spp upto some extent and Polyester fabrics can inhibit the growth of Corynebacterium spp and Staphylococcus spp.

All type of bacteria can grow on wool, but due to high absorption of sweat and malodour, very less odour is emitted . Bacteria like Enhydrobacter aerosaccus and Propionibacterium can grow on almost every type of fabric. But unable to grow on Fleece and Viscose fabrics.So now we know the difference in odour generation and variation in bacterial growth according to the type of fabric.

But what is the solution to this malodour? To address this problem, Scientists are trying to use bioactive substances like triclosan, silver ions , chitosan etc which can kill or inhibit the growth of these odour producing bacteria. They also tried to used antimicrobials , but it can prove to be dangerous when used in an uncontrolled manner and can add to the problem of antimicrobial resistance. But maintaining personal hygiene, washing clothes on regular basis with appropriate detergents and limiting the use of fabrics susceptible to malodours is still the best option.
So friends never get embarrassed by smelly clothes , its not you but these microscopic vagabonds who are responsible for this!

Kartik Jayant Deopujari

TyBsc Microbiology