ICE ICE, BABY

 (View from Gulmarg: Photo taken on 13 May 2012 by PRC

It was not so long ago that we received a severe jolt  from the Intergovernmental Panel on Climatic Change (IPCC) that  the Himalayan glaciers  will be disappearing into thin year by roughly 2035.  This meant  serious  repercussions. Possibility of   rivers of Indian Peninsula and China, which originate from these glaciers, drying up, loomed large.  What an  unimaginable socio cultural, economic  and geopolitical  crises this would lead to ?  2035 is too close  a time frame  for comfort    and there  was frenzy all around.  I am sure there might have an unprecedented rush to visit the holy shrines and scenic places in the Himalayas before it was too late.    Fortunately for everybody , the preposterous hypothetical prediction was soon withdrawn,  with the  explanation that all parameters  that   govern the waxing and waning of glaciers  were not taken into account.   

Though almost akin to bank balance it is indeed it is very difficult to monitor the  credit and debit pattern in ( or of) glaciers.  Credit  accrual  is when snow fall and avalanche get deposited and  debit is through melting  and caving.   But  these don’t appear as neat line items on adjacent columns as in a bank passbook,  so that we can check out the balance easily.   (In a way it is as unpredictable as  foretelling the occurrence of  puddles  that  rains leave behind  along the length and breadth of  Bangalore roads. ).   Sure  there are so many unknown debits and credits, but then there  is so much of balance  as of now that we needn’t worry for the time being.  Still there are causes for concern.  Because  aren’t there  instances,  when family  wealth,  accumulated over generations, is often splashed away  by spendthrift  great grand children in a jiffy?

Hence it cannot be denied that global warming will  adversely affect the glaciers, however imperceptibly it might be.   Attempts  are being made by several scientific groups globally  to study this . Bolch et al (1) in the April 20^th issue of Science ask the pertinent question: How can we  make periodic,  three dimensional (length, depth and area) inventory of the  glaciers?.  In their opinion, location observatories, coupled with   remote sensing  techniques  and accurate modeling  would be one step forward.  Just as  the high and mighty Himalayas, Antarctic ice sheets   too  are  sending faint yet  sure signals of melting.  Pritchard et al ( 2) draw our attention to the fact that  the  repercussions may be felt   in a time frame of decades,  as an  infintesimal yet definite  increase in sea level.

Warm climates have ushered in  other unexpected ecological changes, so Pauli et al (3)would like us to believe.  Over a seven year period the team  monitored the  biodiversity (floral) across major mountain ranges in Europe.  The results seem to justify their  hypothesis that global warming might  drive plant species up the  mountain slopes. It would indeed be interesting to conduct a similar study along the Himalayan slopes.  First in the series should be " Is the Valley of Flowers receding ?"  Would be exciting to be part of such a scientific expedition.  

Europe has been closely monitoring  Mother Earth , through its eyes in the sky the  ENVISAT.   Since  2002 this satellite has been  providing European Space Agency (ESA)  with the vital statistics of Earth through a variety of multiply enabled instruments.  ESA received signals from ENVISAT till 8th of April 2012.  Since then there has been no contacts.  The implications are that the satellite's main computer or the power up system  might have failed. This has crippled a lot of agencies who are dependent on data from ENVISAT (4) 

Tailpiece :

Read about an interesting experiment to protect the glaciers of Alps.  Those concerned decided to  insulate them by wrapping them in  blankets ! 

 .http://environment.nationalgeographic.com/environment/global-warming/alps-meltdown/

References :

1.The state and fate of Himalayan Glaciers : Bolch et al  Science 20^th April 2012, Vol. 336, pages 310-314
2.. Antarctic ice-sheet loss driven by basam melting of ice shelves : Pritchard et al  Nature 26^th April 2012, Vol. 484 pages 502-505

3. Recent plant diversity changes on Europe’s mountain summits: Pauli et al  Science 20 April 2012, Vol. 336, pages 353- 355.

4. Europe loses sight of Earth : Brumfiel, Nature 26th April 2012, Vol. 484, page 423

4. Europe loses sight of Earth : Brumfiel, Nature 26th April 2012, Vol. 484, page 423

Evolution : FACTS and FUN

Evolution is a  serious  game in progress, of course at an impercetably slow pace. For us mortals, with short  life spans,   nothing really changes.   Mother Nature,  with her assistant  Natural selection, has been   playing the same game of speciation and divergence for close to 4 billion years. 

            One of the best fossils to study  various aspects of evolution   is the  simple tooth. (1).    In fact many extinct animals have left  behind only their fossilized teeth for us to know and  weave tales about them; how big  they might have been and what they would have eaten.  There are indications that though  jaws and teeth evolved independently, somewhere along the  evolutionary time lines, their pathways merged with the result that several things were firmly established once and for all.  The location of the teeth  on the jaws,  their function and  enabling dental features.  The frontal incisors and canines  help in  grasping and tearing, premolars and molars are  predominantly grinders, though they can also cut.   Cusps, the conical projections    on the surface of the molars  are   the enabling features to aid grinding and cutting process.    From the single cuspid reptilian to multi cuspid mammalian, there  are large variations in the dental features between species, but  relatively less within a  given species.   

            Harjunma et al(2) were fascinated by the developmental biology of  molars in laboratory mice.  Mice teeth are limited to   incisors and molars. In laboratory bred  mutant and transgenic mice very often cusps  are totally absent.  Except aesthetics,  these flat teeth may not have much functional use. Poor mice, flat teeth would have  robbed them off the whole  enjoyment of eating.  But why flat teeth, what leads to such a strange situation?.  Scientists have identified at least 29 gene mutations which can affect teeth formation in multiple ways, absence of cusps included. Mutation (altered  message) is one thing and signalling, (sending the message across to  intended recipients) is another thing.  Signals are clues to  turn on or turn off  or slow down  specific biochemical processes.   Tinkering with three such signalling pathways simultaneously   the team could ultimately increase the number of cusps even beyond the normal.   Harjunma team suggest that  there could be  multiple genes  at work in imparting cusp pattern to molars.  Adjusting  three genes they could make the cusps reappear, but then, in all possibility,  something else might have  gotten  impaired ?  No wonder evolution is a slow process, it is so intricate, so many messages need to be so finely balanced.......
 A friend of mine, who is working in the area of drug research,  spoke to me recently about   the  long years of study needed to zero in on a drug molecule.  A very promising  drug molecule  may prove to be causing some other ailment as a side effect. For example it might cure cancer but might lead to blindness. That is not acceptable.  Biological signals are never dedicated " For your eyes only"  type. One single signal  might be meant for several recipients and each  recipient  might interpret it in a different way. Hence the need for fine coordination. And that takes enormous amount of time.  

“Tailpiece”

Playing the same game for close to 4 billion years  is not  a joke. Boredom is sure to  creep in at times and  that  is when Mother resorts to a few naughty tricks and treats. Her lazy assistant Natural Selection lets the players fight it out for survival, to decide   who wins and who gets wiped out.  Evolutionary biologists of course would  interpret these  as are necessary and well orchestrated  examples of  adaptive evolution, or survival tactics.   But just imagine wouldn’t it  be more fun to accept these as simple acts of pranks?  Take for example.  the rampant  practice of mimicry(3,4): the   Australian insect which resembles a twig,  the harmless hoverfly  which imitates the looks of the  sting bee,    the  venomous Texas coral snake and its innocuous twin, the  Mexican milk snake. 
More about mimicry  later 

1.Evolution and development of teeth McCollum et al   J. Anatomy. 2001 199, pp. 153-159

2. On the difficulty of increasing dental complexity: Harjunmaa et al Nature 2012, March 15, 483, 324-326.

3. Comparative analysis of the evolution of imperfect mimicry  Penney, H D et al, Nature 2012 March 22,   483, 461-464

4. A taste for mimicry ; Ruxton et al  Nature 2005 , January 20 ,  433 205-206

Social Networking: From Paleolithic to Facebook Era ........

Hadza(1) is a fast disappearing aboriginal tribe in Eastern Africa; Tanzania to be precise.   Hunters and gatherers for several thousands of years,(naturally, women are the gatherers and men the hunters) they communicate through clicks(2). They live  usually in small  groups of about 25.  The groups are loosely knit; members could come and go as they please, no questions asked nor answers sought.  Personal freedom is at the zenith.   Married couple can opt out of matrimony by living separately  for a fortnight, or by  adopting  the dress code of the  unmarried.   To  our civilized myopic eyes their  social norms or traditions are just a blur or altogether nonexistent.   

In forager societies there is no concept of personal wealth.  They live for the present, no hoarding  or saving.  Hunting is not an individual, but a team  effort, so also consuming the  prey.  Gathering may be a n individual effort, but the amount gathered is  so much that it is   shared.    How does such a group come together? Or rather  what holds such a heterogeneous  group (of  young and old, men and women,  active and lazy) together?   There indeed has to be a high degree of give and take or in modern terminology  Cooperativity.  Do like minded members seek out  each other ?  Are conflicts always settled by those with divergent views moving out?     Apicella and team  (3) reasoned that this is a  ideal system to study the intricacies of human interactions   since  prehistoric times. Because the Hadza haven't changed their ways in the least bit except perhaps  discarding the animal skin loin cloth for the manmade fabric. 

The  research paper published in January issue of   Nature (3)  reports   the social   networking pattern among Hadza tribe. 205 adults (men and women)  spread over 17 groups  were studied.  The sample size may not appear statistically significant;  yet considering the dwindling population, there  indeed is no other option but to accept. The affinity between individuals within the group and  outside group  and their voluntary contributions  for  a common cause came under scrutiny.  The methods used might sound a bit trivial. For example person to person affinity was  measured in terms of  sharing /gifting honey sticks ( high prized item among Hadza) and  choosing a preferred  group mate from a set of photographs.  The team concluded that  cooperativity is the glue that holds a group together. This could spring from  genetic,(parents, siblings, cousins) affinal (marriage)  ties or simple friendship.  They found cooperators  tend to flock together,  and often influence the  non-cooperators to fall in line, or else, get left out.   There is always an undeniable  element of  emotional quotient  when humans are involved. Somehow that seems to be absent in this study.   

  

If cooperativity  is at the core of social networking during prehistoric times, is it relevant today too? What better social networking site than the Facebook, a  vast network of friends and friends’ friends.?  Lewis et al (2) mapped  more than 1500 jottings by college students over a 4 year period, from the time they first entered the college till  they graduated out.  In principle could as well  be  a ‘Developmental Sociology”  project.  Lewis and team are cautious in the anlysis and interpretation of their data.   They did observe  is a tendency to seek out those who have similar tastes in music and films  however no trend to influence others. 

(1) Hadza_people

(2) Click_consonant

(3)Social networks and cooperation in hunter-gatherers: Coren Apicella, Frank W. Marlowe,James H. Fowler and Nicholas A. Christakis,  Nature 2012 481,497-501

(4)Social selection and peer influence in an online social network :

Kevin Lewis, 

Marco Gonzalez, 

and Jason Kaufman,   

Proceedings of the National Academy of Sciences 2012 109 (1) 68-72;

In step with elephants

Switching between walking and running seem natural to us  but  technically  these are   two different activities. Locomotion, which includes walking, jumping and running is an important topic in biomechanics.  Intense  research in the field  of gait analysis   has helped   orthopaedic medicine a great deal  to not only to  treat and  cure but also to  improve  the designs of orthopaedic aids for  the injured and the handicapped.   Also assumes great significance in sports medicine.

The movement of the centre of mass (COM) of the body, the contribution from potential and kinetic energies and  absence or presence of an airborne status  these are the features  that  distinguish a Walk from a Run.  During  walking  the COG moves in a curvaceous manner from side to side akin to an inverted pendulum, as feet take turns to be grounded and airlifted,  there will be fleeting yet recurring moments when both feet are on the ground, and potential and kinetic energy contributions are out of phase.   During  running the COM is bobbing up and down like a bouncing ball,  there are moments when the entire body is suspended in air,  the potential and kinetic energy contributions are in phase and the kinetic energy demands soar.  The same criteria hold good for quadrupeds too. 

While the fleeting airborne status during running is indeed a reality for  humans or agile quadrupeds such as deer or tiger,  could this be true for   elephants too?   Two teams one headed by Professor  Norman Heglund from the Université catholique de Louvain, Belgium  and the other by  Professor John Hutchinson  (  Department of Veterinary Sciences  and  Structure and Motion Laboratory  Royal Veterinary College, London,)  set out to study the way  elephants negotiated distances at slow and faster paces.  The question to be settled was “ do they walk,  or run?”  

A complex proposition indeed. To understand the complexity in its entirety, just  have a look at the  animal   itself.  A mature bull elephant could weigh as much as 5000kg and stand tall at a  3 meters. Give and take a 1000kg or a meter  depending on the generic  and gender variations.   Elephant  legs are  cylindrical columns, in more  precise terms   load bearing pillars; tall, fat and  straight. The feet circumference could range of 120-140 cm.  The front  foot  is quite circular in shape, and the rear  a bit  oval.  Composed mostly of elastic fibrous tissue these are very efficient shock absorbers too. Anyway,  with such proportions it is not easy to have a graceful gait, yet elephants walk majestically. But can they really run?

.

To monitor the gait features of the heaviest animal on earth,    Heglund and team decided to construct a test rig at the  Elephant Conservation Centre (ECC) in Lampang, Thailand.  As Heglund  puts it “an 8 m long, elephant-sized force platform from sixteen 1 meter square  force plates.”  Force plates are devices which work on Newton's Law that every action has an equal and opposite reaction. Complete with transducers,  cameras and computers it measures the ground reaction forces exerted as one  walks on it .  The entire set up   was custom built in  Belgium and shipped to  ECC,  where they  were assembled over a sturdy reinforced concrete platform in the middle of a long gait track.  

It must not have been easy to get the elephants  walk over the  desired path.   They must have  needed excessive coaxing by their mahouts.  Even then  instigating them   to  charge forward  onto  the test rig must have been no less than  close encounter with danger. A herd of 34 elephants including a baby of  870kg  and an adult of 4000kg finally  participated in the experiment.  Speed profiles and  corresponding energy diagrams over the center of mass were recorded for each one separately. 

Now to the results:  believe it or not the elephant  is indeed a very very energy efficient  animal.  The team found out  that  the energy expenditure on locomotion for an  elephant’s  is 1/3rd that of humans and 1/30th that of mice.  Elephants  take quicker steps; ( high “step frequency”).   At slow pace they have 3 feet grounded and in  "faster mode " have two feet on ground. While this effectively keeps the COM  displacement  and hence energy requirements to a minimum,    doesn't  qualify for running; because the mandatory  airborne phase is absent.      However energy diagrams recorded a slight vertical displacement   of  the center of mass ( bouncing),  characteristic of trotting during the second half of the gait cycle! 
Ha so the elephant walks as it trots!     

1. Biomechanics of locomotion in Asian elephants J Exp Biol 213, 694-706.2010, Genin et al

2. Integration of biomechanical compliance, leverage, and power in elephant     limbs    Proc. Natl. Acad. Sci. USA 2010 107:7078-7082. Ren et al

3. .http://mathaware.org/mam/2010/essays/TongenWunderlichRunWalk.pdf

4. http://www-personal.umich.edu/~ferrisdp/Farley&Ferris,1998.pdf

Hair raising experiments

Who isn’t worried about hair? Age and gender  take a  united stand against this common enemy.   And what challenges!    Either it is too oily or too dull;  too thin or  too bushy;  too curly or too straight to be styled;  greying too fast or too dark to take up any color!  Every third commercial in the TV suggests solutions with desirable outcomes. Pick your choice.

Besides being the crowing glory, body hair as an integral part of skin plays  an important  role in maintaining homeostasis. The hair that sticks out of the skin is actually a string of dead cells. But can there be death without birth?  Indeed hair  too goes through a birth and  growth period before embracing death.

Life cycle of the hair is actually   the  life cycle of  the hair follicle.  No new hair follicles are made postnatally, the lower portion of the follicle goes through cycles of regeneration  to produce new hair to replace the old.  For this  we are born with a storehouse of stem cells  Anatomically this storehouse is  called the “bulge” ( a rather unscientific term, I agree) at the base of the hair follicle.  These stem cells  are pluripotent, means they can   differentiate into adult hair follicles, epidermis or  sebaceous glands.  Because of the pluripotency  and also because they can be easily cultured in the lab,  skin stem cells  have attracted considerable scientific curiosity.  Several laboratories  around the world are  actively involved in  unravelling the mysteries of the skin and hair.   

Anagen and Telogen are the active and resting phases of the hair follicle  cycle.  The dynamic transition from growth state to rest state is the catagen phase.  During the anagen phase the hair follicle sports  vigorous growth and hair forms.  How long the anagen phase prolongs decides how long the hair will be. But this is genetically predetermined. At the end of the growth phase,  the blood and nutrient supply to the follicle is cut off and it  shrinks and shrivels.  The nascent   hair is pushed up to replace the old one. The shrivelled follicle rests before getting rejuvenated for the next cycle.  Every single hair follicle goes through these three stages albeit  not at the same time.  The  green, amber and red signals  during the hair  life cycle is definitely not synchronised. Imagine  shedding all our sclap hair in one go! What a disaster. Likewise hair on the scalp  has a different  cycle time than the one on the eyebrow or for that matter hair on the hands.  There are instances of synchronized seasonal  cycles.  For example it has been reported that in several breeds of  sheep  the hair is in the telogen phase during winter months. When the ambience warms up in spring the follicles move into anagen phase and  get  ready to shed the old hair.  

Sure enough there is a circadian rhythm at work and scientists  had recognized this very early. The biological  Master clock is in the hypothalamus, (suprachiasmatic nuclei to be precise) but then there are a few autonomous ones scattered elsewhere in other tissues, skin being one among them.  The circadian rhythm is implemented through  a very intriguing interplay among   sets of proteins called, CLOCK, BML1, CRYs and PERs.  The dancers frequently change partners,  take quick  forward and backward steps, ( positive and negative feedbacks)   to  regulate the anagen, catagen, telogen phases.      

Janich et al (3)  conducted in vivo and in vitro studies on special breed of rats. They focussed on the  “bulge” stem cells.  The stem cells have two classes of population: one group  in an “Ever Ready to Go” state, while the remaining   lazily dozing off.    What causes this class divide.  isn’t yet clear. But      Janich et al observed that by disrupting circadian rhythm  they could either increase or decrease the population ratio.    However   upsetting the circadian rhythm  proved  detrimental because it  led to premature aging.

1. Epidermal stem cells: Properties, markers, and location

Robert M. Lavker  and Tung-Tien Sun

PNAS December 5, 2000 vol. 97 no. 25 13473-13475

2. Epidermal stem cells of the skin.Blanpain C, Fuchs E.  Ann. Rev. Cell Dev Biol  2006;22:339-73.

 

3. The circadian molecular clock creates epidermal stem cell heterogeneity.

Jannich et al Nature Vol. 480, 209-214, 2011.

4. Clock genes, hair growth and aging

Mikhail Geyfman and Bogi Andersen AGING, Vol 2, No 3 , pp 122-128, 2010

 

Science and Technology for the Developing World

 Earlier  published in  JFWTC Journal, Volume 5, Issue 2, 2009

With the developing countries increasingly poised to dictate the global market trends and growth potential, it is only appropriate that focus shifts to their specific needs. So what exactly are the specific needs of the developing world? Topping the list are obviously clean water, energy and healthcare at affordable costs. The qualifier “at affordable costs” has a universal appeal not just restricted to developing nations. Human mind is tuned to equate low cost with low (read less efficient) technology; a grave misconception indeed. High tech and low cost are not necessarily mutually exclusive as the cell phones technology has proved admirably. So the need of the hour is innovative ideas. Governments in the developing countries are getting sensitized on the power of science and technology as strong enablers for national progress and are open to ideas from all segments of the society.

Govt of India, for example, has floated several platforms for the collaboration of scientists and technologists with entrepreneurs to fast track “an innovative idea to market”. The Techno Entrepreneurial Promotion Program (TEPP) is one such initiative under the Department of Scientific and Industrial Research, Ministry of Science and Technology, Government of India. TEPP recently came forward to partner with the GE Edison Challenge, the annual technical challenge for students organized collectively by GE India Technology Centres and hosted by JFWTC, Bangalore.

This year students were challenged to come up with a technical solution, practical and sustainable for the energy needs of a small Indian rural community. TEPP volunteered to award Rs. 20,000/- as seed money for each of the 18 finalists to build models prototypes to substantiate their ideas. Subsequently each team will get to interact with a business incubator cell to prepare a strong business case. They could then approach the TEPP for the second phase of funding to translate their ideas into reality. As Dr A.S. Rao, former Director of TEPP puts it “Of course this is investing in risk. Perhaps less than 1% of the funded projects will mature into successful products / business. But it is worth the risk .”

Other devloping countries are not lagging behind either.Last year in Mexico and this year in Durban, I got the privilege (Accompanying Person, as the Academy puts it ) of seeing at close quarters the workings of the Academy of Sciences for the Developing World (TWAS). The events th th were the 10 and 11 Annual General Conferences of the Academy respectively.

TWAS is a consortium of distinguished scientists and engineers founded in 1983 with head office in Trieste,

Italy. Late Nobel Laureate Abdus Salam was instrumental in this intiative. One of the focus areas of the organization is sustainable development through science and technology, a common thread linking ~900 members across 100 countries: 85% of them from developing countries. TWAS firmly believes cultivating scientific temper is key to alleviating the miseries of the developing world and works very closely with Science and Technology Ministries to promote scientific research in key areas. Besides, the Academy has in place a host of other programs and activities too. For example (TWOWS) is a platform exclusively for women in science and engineering, while Inter Academy Panel (IAP) focuses on International Issues. The IAMP (InterAcademy Medical Panel) and the Consortium on Science, Technology and Innovation for the South (COSTIS) have broader playing fields.

More often Science and Technology per se cannot provide complete solutions. Efficient management is equally important. A case in study is eThekwini; the Water and Sanitation Services for the city of Durban. To begin with Government of South Africa treats water as a human right and provides 200 litres of water to every household every day free of charge. This is the baseline. Any requirement above this threshold is charged on a well defined slab system. EThekwini has 29 decentralized waste water treatment plants (DEWATS) in which it treats 500 million litres of waste water per day.

Tailpiece

While at Durban, I visited the Phoenix farm, the first ashram Mohandas Karamchand Gandhi founded in 1904. Most of the original buildings were destroyed in ethnic violence in the 80’s but the house and an office have now been rebuilt on the same site. The building which originally accommodated the printing press is currently a school and the house, a simple structure, a sort of museum. It was here that Gandhiji gave definite shape to building an egalitarian society based on the principles of nonviolence; it was here his ideas on satyagraha took root. It was electrifying to touch the printing press which must have churned out copies of Indian Opinion. Photographs and original letters are displayed on the walls of the house; many of them rare and precious. These bring into focus momentarily the man and the workings of his noble mind. For example the one Gandhi wrote to his elder brother regarding a family feud. 

Outside the mango trees were heavy with fruits and of course the fruits tasted divine

Of Microbes and Men

 Earlier published in JFWTC inhouse Journal  

A microbial power plant?   Concept is not new, has been bouncing around for almost 100 years.  Bruce Sterling’s science fiction “Distraction” set in the year 2044 does allude to it.  A series of articles in a recent issue of Nature ( 18^th May 2006)  focuses on microbial capabilities and efforts to harness them for serving mankind.  A team of   electrical engineers, microbiologists, biotechnologists and environmental chemists spread across globally, definitely see  a possibility, albeit  not immediate. There are several hurdles to overcome before  the lab  model becomes a commercial reality.

The focus is on the oxidative metabolic pathway of the microbes.  Chemically oxidation is stripping of electrons and reduction is gaining of electrons.  The essential consequence of the oxidative metabolic pathway is an electron transport chain which begins with  the nutrient  and after several steps  ends at oxygen.  Flow of electrons means passage of current.  So in a microbial soup if you can siphon off the electrons onto a suitable anode instead off to oxygen,  while continuously replenishing the nutrient medium then you have a fuel cell.

Yuri Gorby¹ and his team have put to work photosynthetic bacteria Synechosytis in a microbial fuel cell.  Central to this set is Gorby’s observation that the bacterial surface has thin whiskers of nanometer dimensions which together with cytochrome  facilitates conductivity.

At Penn State University Bruce E. Logan² and his colleagues are using these miniature power plants to clean wastewater and also to generate hydrogen.  By blocking the supply of oxygen and a meagre input of 0.25 volt, the team could achieve four fold increase of hydrogen production. 

The current per se might be infinitesimally small, but the potential?  That is what  Prof. Peter Girguis’³ team at  Harvard  is interested in.  But the problem is to make the electrodes “ bacteriophilic” or coax the bacteria to get closer and adhere to the electrode.

A couple of years earlier Schroder etal⁴ from Institute for Chemistry and Biochemistry, University of  Greifswald, Germany used platinum with a coating of poly (tetrafluor aniline) to  improve electrode/bacterial interface.  They reported Clostridium butyricum or Clostridium beijerinckii with   carbohydrates as nutrients could  generate  current densities between 1 and 1.3mA/sqcm. 

Recently Willy Verstraete and his team⁵ (Laboratory of Microbial Ecology and Technology,   Belgium) demonstrated that when microbial fuel cell units are stacked together the power output could be multifold. They reported a  “Maximum hourly averaged power output of 258 W m^-3 using a hexacyanoferrate”. Their observation that in an MFC, the microorganisms colonise  as a biofilm and live in close contact with the electrode  is a crucial piece of information.   Because biofilms  are the toughest architecture of bacterial colonies and might be the surest way to improve the electrode-microbe interface. 

Kolter and Greenberg⁶ report that when bacteria opt  to settle down as a biofilm it secretes a glue which holds the colony together and also helps the film  cling  firmly onto the substrate surface.   Biofilms of microbial colonies  are tough, mutate quickly and become drug resistant.   Naturally    Kolter’s   interest is in rupturing the  film  so as to  break up the colony and subdue the microbes on a one to one basis.    But from the MFC  perspective   important question to ask is can we facilitate the secretion of that glue  selectively so  that the MFC microbes  adhere more firmly to  the electrode surface ?

1.      Batteries not included : News Feature ,  Lane, Nature 441, p274 (2006)

2.      Increased power and Coulombic efficiency of single-chamber microbial fuel cells through an improved cathode structure, Logan etal.  Electrochem. Comm. 8:489 (2006).

3.      Circuits of slime:   News feature,  Schibert,  Nature 441, p276 (2006)

4.      Electrochemistry Communications, Schroder et al   6, p955 (2004)

5.      Continuous electricity generation at high voltages and currents using stacked microbial cells,  Verstraete et al  Env. Sci. Techn 40, 3388   (2006)

6.      Superficial Life of microbes: Kolter and Greenberg,  Nature 441, p 300 (2006)