my name is bonnie bassler
i'm a scientist i work at princeton
university and also at howard hughes
medical institute
my group works on a on bacteria on a
process called quorum sensing
so what we always wonder about is how
bacteria get any bang for their buck
right they're itty bitty
ancient yet they do all these horrible
things and also all these miraculous
things and so we try to understand how
do they do these powerful tasks
and so what we showed is that in a
process called quorum sensing bacteria
communicate with chemical words and they
orchestrate group behaviors so they know
when they're alone they know when
they're in groups and they do different
things under each of those two scenarios
so the way quorum sensing works is that
bacteria
when bacteria grow and divide they just
cut themselves down in the middle and
one becomes two two becomes four four
becomes eight and as they're growing
they make and release small molecules
that we call autoinducers but you can
just think of them like hormones so the
more bacteria there are the more of
these molecules there are around them
and when the molecules hit a particular
amount the bacteria detect them and they
infer from that detection event that
they must have neighbors around so in
unison all of the bacteria change their
behaviors together and they begin to
carry out collective or group behaviors
and those are tasks that it takes lots
of bacteria acting together to make the
task successful because individually the
bacteria are too small
to carry the task out so they're sort of
like acting like armies right they know
when they have the right number of cells
around and then they all
launch
together and that we now call quorum
sensing they know when they have the
quorum the group that is enough
to make something
happen productively
i think we need to understand quorum
sensing because it changes
the our understanding of the profound
importance of bacteria in nature and
medicine so bacteria have been known for
500 years
and they've always been thought to act
as these asocial individual sort of
recluses and what i mean by that is when
one bacterium divides into two it has no
knowledge if you will or interaction
with its sister cell right so they've
always been thought to act as
individuals
now we know about quorum sensing the
bacteria act in groups that they use
chemicals to talk to each other right
and to understand how many are around
and also who their neighbors are there's
multiple molecules some say self some
say other right and because we now know
that it gives us totally first of all it
gives us a completely new way to think
about evolution right you know that the
most ancient organisms on earth
evolved social behaviors evolved
language if you will evolved group
behaviors right so so you can study
study these
traits that are
fundamental to life in these simple
organisms that's one thing which i like
because i like to make discoveries but
the second thing is it's an achilles
heel right so if you can make bacteria
so they can't talk or they can't hear
right so that they don't understand that
they're in groups
they don't launch these
pathogenic behaviors so there's a whole
new way to think about how we might come
back combat global pathogens by
disrupting quorum sensing mediated
communication
and stopping harmful bacteria i got into
this field this quorum sensing field
kind of by accident i wish it was a
really sophisticated decision but it
wasn't and maybe that's good for younger
scientists or anybody who's thinking
about whatever their career is to think
about so i'll tell you my um checkered
past
so i was a finishing graduate student
i worked on bacteria i worked on vibrios
and um i went to my i got the good
fortune to go to my very first science
meeting so i was sitting in the audience
with hundreds of people
dutifully listening to these talks and
mostly i couldn't understand them they
were completely impenetrable you know i
just blown out of the water as soon as
the person started talking and then when
i could understand them i didn't think
they were very exciting and so i
remember i was kind of daydreaming like
do i even like science you know is this
for me
and then this man got up whose name is
mike silverman and he will become my
postdoc boss in a little bit so he it
was his turn to talk
and he got up and he told about what was
then i mean i remember this a long time
ago now you know the original finding
and so what had been discovered was that
there was a bioluminescent bacteria
completely harmless this beautiful
marine obscure marine organism that had
the special trait that made light blue
light and so what he had shown is that
when the bacteria were alone they made
no light but when they grew to a certain
cell number they all turned on light
together and so that
trait made the invisible world of the
bacteria visible to him
the scientists
and then what he did was he made mutants
that were goofy in making light you know
he they didn't make light when they
should or they did make like when they
shouldn't and by doing that
he got the first genes in quorum sensing
that there was a molecule
there was a receptor you know and then
like i told you the molecule accumulated
the receptor bounded and it turned on
the light producing genes it was so
simple all he did was turn the lights
off in the room go in the dark room and
look for a mutant for colonies on petri
plates that were were weren't making
light at the right or wrong time
and then so okay so i'm sitting in the
audience i guess i was like a 25 year
old woman at that time
i've been working on bacteria since i
was an undergraduate and i was thinking
they're doing this thing together you
know like like it was unheard of
and i was like how can i not know this
you know i'm supposed to be a bacteria
person right how and and i just thought
that was so it i think was my only
epiphany in my life i was like that is
so amazing that these bacteria can do
this thing together and surely i'm smart
enough to turn the lights off in the
room and figure out which ones are dark
and which ones are bright i mean how
hard could that be
and then i and i also thought that
you know this guy was either crazy or
that was like an amazing thing
right and so i literally you know ran up
to the podium after his talk was hanging
off the podium desperate like you have
to take me as your postdoc you know he
doesn't know me right and then
eventually with enough persistence he
did
right and and i think what was you know
was so you know it was just luck that i
was sitting there it was luck that he
was a speaker
it was luck that i was listening
actually but then also like when i think
back about that you know how'd this get
missed for 500 years right
you know until silverman mike silverman
you know made that incredible discovery
um
you know bacteria are invisible right if
they're doing something together or
something alone you can't see them you
know so how would you know right and
also this is all before we had
sequencing and all these fantastic
techniques and fluorescent reporters
that we have now and so this crazy
beautiful trait of bioluminescence that
was built in
right you know that that made them
visible and you could track it and you
could measure it right it was just just
an incredible gift from nature and i
truly don't know why you know okay so
now i've never worked on anything since
then right and um
i don't understand why that
sparked my interest so much because it
was harmless it wasn't you know a
pathogen and you know but he was it was
just a captivating talk
and
you know later
not then i don't want to pretend like i
was smarter than i was later you know
this idea of group behaviors i mean
that's central to life you know
right we know
cells and tissue active group organisms
act as groups you know so so now it
makes sense but then it was just this
amazing
talk
about something that to me was
completely otherworldly you know and i
also would just say maybe this will be
for the younger people
i don't know how
that then young woman got the courage to
go up to the podium because i would
never ask a question in a seminar i
would never i was so intimidated and
scared and somehow i did
get the courage to ask and like when i
think back on that you know if if he
just said no
you know i'd be where i was i wouldn't
have died from that you know might have
felt like it but you know like what was
you know and so somehow that young woman
crazy scared you know got up and
actually did something good for herself
right and i literally have never worked
on anything since greatest moment of my
life
i'd say something for um
younger scientists that are getting into
it and i think lots of times um
younger scientists get frustrated or
think that they're not cut out for
science you know because experiments
don't work or they find you know the
classes or lab work really hard and so i
think that younger scientists confuse
challenging with not any good at it and
they're not the same thing
right like
i don't think we really want to watch
reality tv at starting at five o'clock
at night you know for the rest of your
life what you want
is a career you know in a vocation that
challenges you and keeps you engaged and
keeps you passionate and keeps you
wanting to come in you know like i've
come into this freaking building every
day for almost 30 years and i still come
running in because i think there's going
to be a surprise in the incubator right
um you know and and but but
but it has been difficult in the sense
of not easy to figure out and of course
not if you're really working on big
fundamental questions in this case that
these bacteria have a 4 billion year
head start on this figuring this stuff
out we've only been doing it for 30
years right you know they're really hard
to figure out or so either somebody
would have figured it out already you
know or maybe it wouldn't be important
and i would really just say to young
people don't confuse
challenging with not having a talent for
something they're not the same thing and
i think those things get conflated all
the time and young people think i'm not
good at science you know and i you know
because i gotta be on my test or because
my spirit you know that's what you want
because it means you're picking a
vocation
that is challenging right and that i
think the best life in the world is one
where you get challenged to be your best
you know your smartest or you know on
top of your game
every single day or almost every day
right yeah so that's just sort of a
message that i did i find
you know i don't know why i didn't
i already told you why why didn't i quit
earlier was you know because i never
had done anything else i was too scared
to do something else but i'm so glad i
stuck with it because i realized now the
fact that it's challenging that's the
best part of it
right so