5.4 Endophytic Bacterial Communities Producing
Extracellular Enzymes
Endophytic bacterial communities are also considered an important source of
extracellular enzymes. Endophytic bacterial strains have been isolated and identi-
fied from various plants such as pea (P. sativum), tomato (Lycopersicum esculen-
tum), corn (Zea mays), wheat (Triticum aesitivum), oat (Avena sativa), canola
(Brassica napus), barley (Hordeum vulgare), radish (Raphanus sativus) soybean
(Glycine max), potato (Solanum tuberosum), lettuce (Lactuca serriola), and
cucumber (Cucumis sativa). In addition, various bacterial strains have also been
isolated from the economically important medicinal plants species. Some of the
novel strains identified and characterized belong to theArthrobacter, Actinobacter,
Aeromonas, Agrobacterium, Alcaligenes, Bacillus, Azospirillium, Enterobacter,
Flavobacterium Pseudomonas, Acinetobacter, Azotobacter, Beijerinckia,
Burkholderia, Enterobacter, Erwinia, Flavobacterium, Rhizobium,andSerratia
genuses (Gray and Smith 2005 ).
In addition, the bacterial endophytes have been reported for the production of
ACC deaminase, cellulases, protease, amylase, pectinase, esterase, lipase, protease,
asparaginase, phytase, etc. (Sturz et al. 2000 ; Carrim et al. 2006 ). There are a wide
array of resource studies showing that production of these enzymes by endophytic
bacteria is isolated from different parts of the plant (Table5.2). In such exploratory
studies based on agar plate detection methods, Pereira et al. ( 2016 ) examined that
Lavandula dentateharbored more than 30 endophytic bacterial strains. These
endophytic microbes produced cellulases, lipases, pectinases, and proteases besides
improving the growth of the host plant. In phyllosphereic part of theLavandula
dentate, the endophytic microbes produced higher quantities of plant cell
wall-degrading enzymes, as also evidenced by Verma et al. ( 2001 ) who have
reported higher number of endophytic bacteria from diazotrophs plant and their
growth regulation by producing cellulase and pectinase.
In species-specific bacterial strains,Nocardiopsissp. (39.2 U mlâ^1 ) identified to
secrete higher quantities of thea-amylase as an extracellular enzyme during dif-
ferent growth stages (Stamford et al. 2001 ). Davis et al. ( 1980 ) showed similar
prospects forBacillus stearothermophilus,whereas Castro et al. ( 1993 ) forB.
amyloliquefaciens. The authors revealed a strong association of enzymes produc-
tion by bacteria during different growth stages. Whena-amylase was produced by
Lactobacillus plantarum, maximum enzyme synthesis occurred during stationary
phase (Giraud et al. 1993 ). Vijayalakshmi et al. ( 2016 ) isolated endophytic bacteria
from medicinally important plants, producinga-amylase, protease, and cellulase. In
one of the recent reports, Leo et al. ( 2016 ) observed the recovery of endophytic
bacteria (Alcaligenes faecalis, Burkholderia cepacia, and Enterobacter hor-
maechei) from perennial grasses that showed the hyper-enzymatic activity of
a-amylase, protease, and cellulase.
Bacterial endophyte,Pantoeasp. Sd-1, isolated from paddy shows a higher
ligninolytic activity (Xiong et al. 2013 ). Castro et al. ( 2014 ) suggested that
5 Endophytic Microbes: A Resource... 103