

































 Paenibacillus lautus has a wide variety of environmental and clinical sources and contains many survival mechanisms 
that may contribute to pathogenicity. P. lautus demonstrates pro!ciency in the degradation of cellulose and diesel, 
resistance to high temperatures and heavy metal exposure, bio!lm and endospore formation, and persistence in 
various digestive systems. It has also been shown to utilize swarming motility and reversible phenotypic switching, 
both of which may be factors in increasing pathogenicity and human infection prevalence due to the extensive 
bacterial communication necessary to carry out these processes. It is important to be aware of these factors as 
they relate to the broader"Paenibacillus"species, particularly by comparing the phenotypic switching and complex 
swarming motility patterns of"P. lautus to those of P. dendritiformis and P. vortex. Targeting this communication may 
be the key to developing e#ective antibiotics in the case of a multi-drug resistant strain of"P. lautus."By knowing the 
pathogenic implications of the survival strategies utilized by this species and weighing the bene!ts of its cellulolytic 
and pollutant-degrading potential against its ability to cause opportunistic infection through tick vectors, we may be 
more equipped to handle an increase of human infections caused by this bacterium.

Aisthesis      Volume 15,  202418

Environmental Uses and Pathogenic Potential of 
Paenibacillus lautus

by Kathryn O'Donnell

Introduction
 Paenibacillus lautus is a gram-positive, spore 
forming species of bacteria cultured from a wide 
variety of environmental and human sources (Saez-
Nieto et al. 2017). Originally labeled Bacillus lautus, 
it was reclassi!ed as part of the Paenibacillus genus 
in 1996 due to the extensive genetic similarities it 
shares with other Paenibacillus species (Heyndrickx 
et al. 1996). P. lautus is typically rod shaped; however 
there is evidence of phenotypic switching that 
may contribute to motility and population control 
(Mangwani et al. 2014). $is phenotypic switching is 
reversible and involves the bacteria changing shape 
from rods to cocci in response to environmental 
stress. 
 Paenibacillus species have been found in varied 
environments, including human digestive tracts, 
cow feces, land!lls, hot springs, ticks, human saliva, 
and soil (Yadav and Dubey 2018; Mead et al. 2012; 
Loong et al. 2018; Tetz et al. 2016; Saez-Nieto et al. 
2017). $e diversity in natural habitats may relate to 
the ability to form a bio!lm on objects, the ability 
to form endospores, and the ability to participate 
in phenotypic switching, which gives P. lautus a 
variety of tools to persist and replicate in stressful 
environments (Celandroni et al. 2016). 

 P. lautus can break down cellulose and diesel, 
which may make it an important biological source of 
environmental cleanup in land!lls or diesel polluted 
land (Yadav and Dubey 2018; Mauricio-Gutierrex 
et al. 2020). However, we also must be prepared for 
an increase in opportunistic, or possibly pathogenic, 
human infections caused by P. lautus. $ese infections 
seem to be connected to an over%ow of waste, which 
attracts rodents and therefore ticks, which have been 
shown to harbor the bacterium and may spread it to 
humans (Loong et al. 2018; Canpolat and Biterge-Sut 
2019).

Environmental Sources and Uses
 An important aspect of bacterial studies is 
determining which bacteria contain enzymes 
that can assist humanity in breaking down waste 
products in land!lls and similar environments. 
$ese enzymes are called cellulases and are used 
o&en in the food and paper industries. P. lautus has 
been shown to have cellulolytic properties, which 
could make it a candidate in studies regarding the 
breakdown of cellulose as well as diesel pollutants 
in soil-rich environments (Yadav and Dubey 2018; 
Mauricio-Gutierrez et al. 2020). 



Environmental Uses and Pathogenic Potential of Paenibacillus lautus

Aisthesis      Volume 15,  202419

Cellulose and Diesel Degradation
 P. lautus was isolated from Indian soil, evaluated 
for its cellulolytic ability using a cellulase enzyme 
assay, and was found to be e'cient at biodegradation. 
$e P. lautus strain BHU( has the ability to e'ciently 
produce cellulases at a rate similar to fungi, which 
can be utilized at a large scale to break down cellulose 
(Yadav and Dubey 2018). P. lautus contains 28 genes 
that contribute to fermentation, which makes it a 
valuable tool in breaking down food products, as 
well as over 1,000 genes that code for the ability to 
transport and metabolize carbohydrates (Mead et al. 
2012; Yadav and Dubey 2018). $e ability to utilize 
carbohydrates as an energy source is useful for a 
potential biodegrading organism, as they o&en come 
across a wide variety of food sources. 
 P. lautus and other gram-positive organisms 
seem to have the ability to break down organic 
pollutants. One frequently problematic soil pollutant 
is diesel spills, which can occasionally be relieved 
using the addition of biodegrading bacterial species. 
Instead of degrading cellulose, P. lautus would be 
given the task of breaking down diesel into digestible 
forms. Luckily, P. lautus has protective mechanisms 
that allow membrane-bound oxygenases to utilize 
hydrocarbons to alter the hydrophobicity of its 
plasma membrane, thus protecting the organism 
from being broken down by toxic pollutants like 
diesel (Mauricio-Gutierrez et al. 2020). Many 
indigenous bacterial species in diesel-polluted 
soil have hindered growth when exposed to high 
levels of pollutant, but there is evidence suggesting 
that some P. lautus strains are able to resist this 
decrease in growth, possibly due to adjusting their 
hydrophobicity with hydrocarbons (Mauricio-
Gutierrez et al. 2020).
 $e ability of P. lautus to degrade diesel varies 
greatly depending on the speci!c strain used. 
Paenibacillus lautus M1CH27 was able to break down 
a signi!cant amount of diesel compared to other 
bacterial species but was not able to continue growth 
as well as Paenibacillus lautus M1CH19, which could 
proliferate when exposed to high levels of diesel in 
soil but could not break down the diesel e'ciently 
(Mauricio-Gutierrez et al. 2020). $is may suggest 
that there is also strain-dependent variation in 
cellulase production, which could be a topic of future 
study (Mead et al. 2012; Yadav and Dubey 2018). 
$ere is great variety in environmental capabilities 

within organisms classi!ed as P. lautus, which could 
make this species an important contributor in the 
search for biological solutions to polluted soil.

Temperature Resistance
 P. lautus has been found in extreme 
environments, including Obsidian Hot Spring in 
Yellowstone National Park. $is indicates that P. 
lautus has adaptations that allow it to persist despite 
harsh environmental pressures, including high 
temperatures (42-90°F) and acidic pH (6.37). $e 
optimum temperature for P. lautus is about 37°F 
(Mead et al. 2012). An important factor that could 
explain this ability is that P. lautus is a known spore 
former, and endospores are extremely resistant to 
threatening environments due to their ability to 
create a tough, outer cortex around the cytoplasm of 
the original bacterial cell. Another explanation may 
be the bio!lm formation of P. lautus (Celandroni et 
al. 2016; Mangwani et al. 2014). Bio!lm formation 
allows bacteria to survive in hostile environments 
by decreasing susceptibility to antimicrobials 
and macrophages. It is unknown whether bio!lm 
formation would be a factor in surviving high 
temperature environments like a hot spring. 

P. lautus Prevalence in Ticks
 Another environmental source of P. lautus is 
within ticks (Loong et al. 2018; Canpolat and Biterge-
Sut 2019). P. lautus was found in the intestines of 
Ioxides granulatus Supino, a tick typically found in 
Asia (Loong et al. 2018). $ese ticks were collected 
from rodents and sanitized with ethanol before 
being homogenized and spread onto a sheep’s blood 
agar plate to harvest cultivable bacteria. $e strain 
of P. lautus identi!ed from these plates had identical 
antibacterial susceptibility to clinical P. lautus 
strains, which creates a concern that these ticks 
could spread these bacteria to humans or animals 
through the process of blood feeding. However, 
there are virulence genes typically present in clinical 
strains that were not present in the strain isolated 
from ticks, which could indicate a di#erence in 
pathogenicity (Loong et al. 2018).
 Ecologists and microbiologists have also studied 
the e#ects of heavy metals on P. lautus, and it seems to 
have a high tolerance for heavy metal contamination 
compared to other related species. $is !nding makes 
the possibility of P. lautus being spread by ticks more 



Environmental Uses and Pathogenic Potential of Paenibacillus lautus

Aisthesis      Volume 15,  202420

concerning, as antibiotic resistant bacteria are o&en 
also resistant to heavy metals in their environment 
(Canpolat and Biterge-Sut 2019). 

Clinical Sources and Uses
 While the environmental uses and sources of P. 
lautus are many, there are also clinical sources of P. 
lautus found in hospital environments and biological 
%uids. $e risk of pathogenicity rises as more patients 
are infected, and the fear in these environments 
is o&en the development of antibiotic resistance. 
To know how antibiotic resistance develops, it is 
important to know which antibiotics P. lautus is 
susceptible and resistant to.

Human Samples
 P. lautus is increasingly being found in clinical 
environments, including biological %uids such as 
blood, abscesses, and wounds, as well as hospital 
environment sources like gloves (Saez-Nieto et 
al. 2017; Tetz et al. 2016). P. lautus has also been 
isolated from sterile body sites, meaning that it is 
most likely not a contaminant. $ese human samples 
are indicative of an increasing prevalence of human 
infections, which may support the idea that di#erent 
strains of P. lautus are adopting human habitats.
 Virulence markers have been found in P. lautus 
in recent studies, lending an explanation to this 
trend (Saez-Nieto et al. 2017; Celandroni et al. 2016). 
$ere are also many virulence markers that have 
been unveiled in a related species of Paenibacillus, 
speci!cally Paenibacillus sp. strain VT-400 (Tetz 
et al. 2016). $is species has been discovered in 
saliva samples of pediatric patients who su#er from 
lymphoblastic leukemia. Paenibacillus sp. strain 
VT-400 is related to P. lautus in multiple ways, one 
of which is the fact that they both seem to cause 
mainly opportunistic infections. However, both 
species seem to have the genetic capability to be 
pathogenic instead of an opportunistic contaminate 
(Tetz et al. 2016; Saez-Nieto et al. 2017). One of 
the most concerning aspects of this possibility is 
the fact that both Paenibacillus sp. strain VT-400 
and P. lautus are spore-forming, and spore forming 
bacterial infections are particularly di'cult to treat 
using antibiotics due to the inherent toughness of 
endospores. 

Antibiotic Resistance
 $e susceptibility of P. lautus to antibiotics is well 
documented. P. lautus is susceptible to cipro%oxacin 
(Canpolat and Biterge-Sut 2019; Loong et al. 2018; 
Celandroni et al. 2016), imipenem (Canpolat and 
Biterge-Sut 2019; Loong et al. 2018), and tetracycline 
(Canpolat and Biterge-Sut 2019; Celandroni et al. 
2016). Vancomycin is also typically included in 
this list, though there has been some evidence of 
resistance to this antibiotic in P. lautus (Canpolat and 
Biterge-Sut 2019; Saez-Nieto et al. 2017; Celandroni 
et al. 2016).
 P. lautus seems to be consistently resistant to 
ampicillin (Canpolat and Biterge-Sut 2019; Loong et 
al. 2018; Saez-Nieto et al. 2017), penicillin (Canpolat 
and Biterge-Sut 2019; Loong et al. 2018; Celandroni 
et al. 2016), and rifampicin, although this antibiotic 
also contains some inconsistencies in resistance 
(Loong et al. 2018; Saez-Nieto et al. 2017).  One 
chemical that seems to be ambiguous in terms of 
susceptibility and resistance is chloramphenicol, 
which P. lautus was listed as susceptible to in one 
study and resistant to in another (Canpolat and 
Biterge-Sut 2019; Loong et al. 2018). 
 $e ability to !ght a P. lautus infection with 
antibiotics is especially important to watch as human 
cases continue to rise, and the possibility of a fully 
antibiotic resistant strain is particularly concerning. 
In general, if a person were infected with P. lautus, 
according to current studies, they could !ght that 
infection with doses of cipro%oxacin, imipenem, or 
tetracycline, while doses of ampicillin or penicillin 
would be ine#ective.

Phenotypic Switching and Swarming Motility 
Patterns
 $ere are a variety of tactics that bacteria 
such as P. lautus use to remain viable in stressful 
environmental conditions, whether that environment 
is inside a living body or deep in the dirt. Some 
of those tactics, described by Be’er et al. (2011), 
Mangwani et al. (2014), and Celandroni et al. (2016) 
include forming bio!lms with swarming motility 
patterns and developing reversible phenotypic 
switching mechanisms to encourage colony survival. 
Both strategies contribute to the bacteria’s ability to 
act as a pathogen or proliferate in an opportunistic 
infection scenario. P. lautus is now grouped with 
other Paenibacillus species based on the many 



Environmental Uses and Pathogenic Potential of Paenibacillus lautus

Aisthesis      Volume 15,  202421

genetic similarities to species like P. vortex and P. 
dendritiformis (Heyndrickx et al. 1996). It would not 
be a far stretch in logic to expect consistencies in 
motility and defense across these species.

Swarming Motility in P. vortex vs. P. lautus
 Paenibacillus vortex cells can form bio!lms, 
which include vast amounts of bacteria that create 
vortex-like swarming patterns (Ingham and Jacob 
2008). $e P. vortex cells are physically curved with 
multiple peritrichous %agella, meaning the %agella 
are uniformly distributed around the cell body. $ese 
cells swim together in a clockwise pattern in optimal 
agar concentrations, which is hypothesized to be 
instrumental in infection, as it requires a large amount 
of communication between bacteria (Ingham and 
Jacob 2008). $is communication may be similar to 
quorum sensing, which is a process in which many 
bacteria sense the size of the colony around them and 
subsequently make collective decisions regarding 
movement or chemical secretions. P. vortex cells 
must communicate with each other about when 
to start swarming, which direction to swim, and 
when to send out snakelike projections which o&en 
form smaller vortices of their own. $ese o#shoots 
occasionally loop over each other as they travel, but 
they largely avoid pathways where other projections 
have already been (Ingham and Jacob 2008). 
 $ere is not a consensus on whether these 
swarming patterns are replicated in P. lautus. One 
study suggests that swarming behavior is seen in P. 
lautus bio!lms, and that there is a speci!c window 
of time in which P. lautus will begin to form vortex-
like patterns (Celandroni et al. 2016). However, 
another study suggested that there is no complex 
cooperative behavior within the speci!c strain of 
P. lautus (Mead et al. 2012). Future studies should 
focus on determining whether P. lautus directly 
models the swarming capabilities of P. vortex, or if 
it demonstrates novel cooperative behavior between 
cells within a bio!lm.

Phenotypic Switching in P. dendritiformis vs. P. lautus
 Paenibacillus dendritiformis is a species related 
to P. lautus that uses phenotypic switching, in which 
the overall shape of the bacterium changes due to 
environmental pressures. Normally, P. dendritiformis 
is rod shaped and motile. In response to stress, o&en 
due to crowded neighboring sister colonies of the 

same species, P. dendritiformis can switch from rods 
to non-motile cocci. $e coccus form of this species 
can proliferate in the presence of sibling lethal factor 
(Slf), which is secreted by colonies of P. dendritiformis 
when they near a sister colony (Be’er et al. 2011). Rod 
shaped bacteria succumb to Slf, forming a barren 
area between neighboring colonies where all bacteria 
have been killed, decreasing con%ict for resources and 
subsequent cell death in both colonies. However, if P. 
dendritiformis is in a coccus shape, it stops moving 
toward sister colonies, and is immune to Slf (Be’er 
et al. 2011). $ese cocci can continue to proliferate 
in the presence of Slf, and when the danger to the 
colony is no longer high, those cells can switch back 
into a rod shape and continue movement in search 
of resources. $is phenotypic switching allows for 
colony survival security, and therefore extends the 
life of P. dendritiformis colonies. 
 P. lautus also seems to utilize this survival strategy, 
demonstrating reversible phenotypic switching in 
response to environmental stress (Mangwani et al. 
2014). Using phase contrast microscopy, confocal 
scanning laser microscopy, and scanning electron 
microscopy, P. lautus colonies have been seen to react 
to bio!lm crowding by switching the phenotype 
of cells in the colony from rod to coccus and back 
again. $is is important to note as scientists explore 
the extent of communication between P. lautus cells, 
since phenotypic switching and swarming motility 
patterns both require intracellular communication. 

Motility’s Contribution to Pathogenicity
 If, as argued by Mead et al. (2012), P. lautus does 
not participate in swarming, it would be a logical 
conclusion to assume that P. lautus is primarily 
found in intestinal sources and was found near a hot 
spring due to nearby animal feces. Bacteria do not 
need complicated motility patterns when they are 
adapted to life within a biological system, as there is 
less of a need for bacteria to provide their own forms 
of protection and movement, since those functions 
are already provided by their environment. $ere 
are also no antibiotic forming genes, heavy metal 
resistance genes, or nitrogen !xing genes within P. 
lautus which are normally found in microbes that 
thrive in hot spring environments. $is study argues 
that P. lautus was !rst isolated from a human child’s 
intestine, which provides an explanation for the 
source of this species when it is found in extreme 



Environmental Uses and Pathogenic Potential of Paenibacillus lautus

Aisthesis      Volume 15,  202422

environments like a hot spring. P. lautus was not 
found because P. lautus thrives in those conditions 
due to complex motility patterns, but because of 
animal fecal matter nearby (Mead et al. 2012). $is 
explanation would lean towards P. lautus being 
primarily opportunistic.
 However, if Celandroni et al. (2016) has the 
motility patterns of P. lautus correctly pinpointed, 
the %agellum-driven motility of these bacteria 
would be an important factor in their pathogenicity. 
Swarming facilitates the invasion of human and 
non-human host cellular barriers, as it allows 
improved communication between cells in a colony 
(Celandroni et al. 2016). $is may be an important 
idea to study in the future, as developing antibiotics 
that target cellular communication may be integral 
in !ghting P. lautus, P. vortex, or P. dendritiformis 
infections.

Conclusion
 P. lautus is found in environmental sources, 
can break down cellulose and diesel, is particularly 
resistant to high temperatures, and is possibly being 
spread to humans through tick bites. It has been 
identi!ed in various human biological sources, 
and there are currently a handful of antibiotics to 
which it is consistently susceptible to in laboratory 
studies. It may participate in swarming motility and 
phenotypic switching, like its cousins P. vortex and 
P. dendritiformis. Future studies on P. lautus could 
focus on exploring the cellular communication that 
allows complex motility patterns and/or phenotypic 
switching, as those mechanisms may be essential in 
!ghting (tick-borne or otherwise) human P. lautus 
infections.
 Another research opportunity on this topic 
would be to determine if the positive in%uence 
P. lautus could have on land!lls as a cellulose 
degrading organism, or on diesel-polluted grounds 
due to its ability to break diesel into digestible forms, 
outweighs the possibility of subsequent opportunistic 
infections in rodents living near land!lls or polluted 
soil. If P. lautus is used as a biological weapon of sorts 
against these issues, will that usage cause an increase 
in rodent infections, leading to tick infections and 
an ultimate transfer to human bodies? By combining 
the knowledge all the previously cited studies have 
gathered on Paenibacillus lautus, we are aware of the 
need to !ght future infections, animal or otherwise, 

and we cannot claim ignorance of the possible 
consequences that may arise from widely utilizing 
the various degradation tools that this species holds.

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Surviving Bacterial Sibling Rivalry: Inducible 
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