Bacteria is something we are all reminded of on a daily basis by merely switching on our televisions where we are bombarded with advertisements for both ‘good’ and ‘bad’ bacteria contrary to the view of the past when only so-called ‘bad’ bacteria was ever talked about, so what has changed? This essay will address the facts about bacteria including their ideal conditions for growth as well as looking at specific examples of how they can be both helpful and harmful to humans.
So what are bacteria? In simple terms bacteria are microscopic, single-celled organisms lacking a nucleus and other organelles such as mitochondria and chloroplasts which are common place in eukaryotes. Bacteria are classified as prokaryotes and have been around for billions of years pre-dating dinosaurs never mind humans (1).
Their minute size prevented them from being seen until 1683 when Antony van Leeuwenhoek invented a simple single-lens microscope though it wasn’t until much later, 1828 in fact that the word bacterium was introduced by a man named Ehrenberg having been derived from a Greek word meaning ‘small stick’ (2). One thing that is clear is that bacteria are more often than not referred to as ‘germs’ which are best eliminated but how many people live happily and healthily without realising that they are carrying at least10,000 more bacteria than there are people on earth (3)?
So if the majority of us can carry so many bacteria and are virtually unaffected do bacteria deserve the bad press they tend to receive? There is no doubt that some bacteria are harmful and have been responsible for causing diseases such as Tuberculosis which, during the 1990’s was the single biggest killer of humans by a bacterium (4), however it has been found that some bacteria are harmless to certain hosts yet fatal to others.
Even though some bacteria have the capacity to be deadly should they still be classed as harmful even if they do not exercise this characteristic? In a broader context could we not compare this type of bacteria with a car for example, in the wrong hands a car can be a deadly weapon but for most of us it is something we use in our everyday lives without ever coming to any harm. Can the same not be said for most bacteria in that they only cause problems under specific conditions?
Take Pseudomonas aeruginosa for example, most of the time it is found living in soil and is viewed as harmless however, to a sufferer of Cystic Fibrosis it is potentially lethal as it has the ability to colonize their lungs causing serious infection if inhaled (5). This begs the question, who is really at fault, the bacteria or the host? Having evolved in their presence humans have serious difficulty with a relatively small number of bacteria so why do we persist in filling our homes with bacteria killing products?
Are we doing ourselves more harm than good? Since the introduction of better standards of hygiene in the home, particularly after the war, many childhood infections have all but disappeared but has a rise in allergies, especially amongst children taken their place? With fewer bacteria around for our immune system to combat many researchers believe our organs are turning on themselves resulting in increased sensitivity to the likes of pollen and dust.
Parts of the world such as Africa are overrun with infection yet allergies are virtually unheard of and it is because of this that scientists have begun trials of vaccines made from African dirt in an attempt to help sufferers of illnesses like asthma, skin cancer and multiple sclerosis (1). Until some definitive answers are found the question of whether ridding our households of as much bacteria as possible and protecting our children from playing outside in a little mud is really helping us in the long run will remain.
No one is suggesting we return to a state similar to that witnessed in the African nations although a happy medium may need to be found if the developed world is to reduce its new found problem of allergies. Bacteria have many talents which have enabled them to inhabit our sometimes inhospitable planet for much longer than any other organism not least of which is the almost unbelievable rate at which they can reproduce.
Like every other living organism there are ideal conditions under which they perform best and as far as multiplication is concerned they require a nutrient supply, an energy source, water, a suitable temperature and pH level which is individual to each species, as well as oxygen, though some do grow better without it and are known as anaerobic as opposed to aerobic bacteria. Pneumonia caused by Streptococcus pneumoniae is an example of an illness caused by anaerobic bacteria where the bacteria inflame and infect the lungs and the bronchial tubes (6).
Although aerobic bacteria are most commonly know for their ability to break down waste they too can cause infections, for example of the soft tissues by the bacteria Staphylococcus aureus. Where conditions are favourable a single bacterium is capable of splitting into two every twenty minutes resulting in between 500 million and 1000 million bacteria being produced after only twelve minutes (7). This is surely a frightening statistic in the context of disease but from another view point, that of scientists culturing ‘friendly’ bacteria it is of major use especially in the field of probiotic drinks.
With the health drink Actimel having been the fastest growing food product of 2004 (8), it would suggest that it is no longer only scientists who are interested in bacteria. It is the kilo of bacteria living in our gut helping to digest food that Lactobacillus acidophilus, found in some probiotic drinks, is believed to help (9). Some scientists believe that probiotics are able to withstand stomach acid therefore enabling their health-giving properties to help treat conditions such as allergies and inflammatory bowel disease (9).
In countries such as Japan and Scandinavia the properties of probiotics that are said to aid our bodies natural defences are believed in so strongly that they are licensed as medicines and can therefore be prescribed (9). In addition to assisting with digestion probiotics are also believed to stop food-poisoning causing bacteria from taking hold with studies carried out at Reading University going as far as to suggest that consumption of this ‘good’ bacteria five days before and during a trip abroad reduces your chances of contracting a stomach ‘bug’ by an incredible 30% (9).
Some scientists however, although in agreement with the health-giving properties of probiotics are rather sceptical about how long their positive effects last for and suggest they are not as hardy as some would have us believe with some not even making it to the colon and those that do stopping working once the drink is finished (10).
Prebiotics have been put forward as a natural alternative, found in fruit, vegetables and grain they travel straight to the colon and are actually able to stimulate the production of probiotics leaving many wondering whether there is really any need for probiotic dietary supplements or whether a well balanced diet which has become somewhat lost under the shadow of convenience foods would do the same job. The most poisonous substance known to man is a toxin produced by a bacteria called Clostridium botulinum.
Botulism claimed the lives of 70% of all those who contracted the illness between 1910 and 1919 before the introduction of mechanical respirators. By the 1980’s this figure had fallen to 9 per cent and in 1993 it was less than 2 per cent (11). This bacterial toxin has the ability to paralyse and kill yet it is now used safely in a purified form marketed under the widely known name, ‘Botox’. It has been found to help people suffering from illnesses where their muscles involuntarily contract by disrupting the vesicles ability to attach to the cell membrane (12) and has been used by those suffering from conditions such as blepharospasm.
Even the most toxic bacteria known to man seems to have its uses and with the massive reduction in deaths caused when in its toxic state its benefits once purified must surely outweigh its negative effects. With advertisements on the television stating that more bacteria can be found on the tray of a child’s highchair than on a toilet seat (13) it is hardly surprising that the average household is filled with bleaches and antibacterial agents as parents try to keep their children safe from illness.
As we have seen bacteria can cause body odour, caries, strep throat and bubonic plague to name just a few from both ends of the spectrum however, they also have a lot of good characteristics which makes them more of a friend than a foe as far as humans are concerned. In short without bacteria we could not survive as we would have no way of digesting our food or producing vitamins nor would we be able to break down the worlds waste so we would in effect being living in the midst of a rubbish dump.
Many of our foods such a yogurts, cheese and wine are all made from bacteria so without them our recipes would all be rather dull. The medical profession would be without antibiotics and the health conscience among us without probiotics. Their ability to live almost anywhere in the world is unrivalled and despite the best efforts of some to wipe them out they are here to stay. More diverse than mammals or insects they will continue to make a substantial amount of the world’s biomass without which humans would not exist.