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Isolation and identification of bacteria having pathogenic interactions with termites (Isoptera)

KrishiKosh

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Title Isolation and identification of bacteria having pathogenic interactions with termites (Isoptera)
 
Creator Yuvraj singh
 
Contributor Sindhu, S.S.
 
Subject Bacteria, Termites, Pathogenic interactions, Biological control, Enzyme activities
 
Description In the present study, the population of bacteria in termite nest soil varied from 1.2 x 106
to 90.0 x 106 colony forming units/g soil on nutrient agar medium. On soil extract agar
medium, the bacterial population varied from 28.3 x 106 to 103.2 x 106 cfu/g soil and it varied
between 2.6 x 106 to 256.0 x 106 cfu/g soil on King’s B medium. Based on colony
morphology, gum production, colony characteristics and pigment production, bacterial isolates
NNY 1-NNY 84 were selected from nutrient agar medium, isolates NSY 1-NSY 40 from soil
extract agar medium and isolates NKY 1-NKY 96 were selected from King’s B medium. From
the gut of termites, bacterial isolates GNY 1-GNY 20 were selected from nutrient agar medium
plates. Isolates GSY 1-GSY 10 were obtained from soil extract agar medium and isolates GKY
1-GKY 20 were obtained from King’s B medium.
A total of 270 bacterial isolates, i.e. 220 isolates from termite nest soil and 50 isolates
from termite gut, were screened for the potential to produce different enzymes, i.e. lipase,
protease and chitinase on specific media. In the preliminary screening, only 83 isolates were
found to express one or more of the enzyme activities. Seven bacterial isolates without any enzyme activity were also selected. For lipolytic activity, the clearance zone to colony growth
ratio varied from 1.24 to 4.20 in different bacterial isolates. Bacterial isolates NNY 73 and NSY
19 showed very little lipase activity and eight isolates did not show any lipase activity. Three
isolates NNY 19, NNY 39 and NSY 20 showed 3.50, 4.20 and 4.00 enzyme production
efficiency, respectively.
Proteolytic enzyme production in different cultures varied from 1.24 to 2.29. The bacterial
isolates NNY 24, NNY 50 and NNY 62 showed highest ratio of clearance zone to colony size
i.e. 2.17, 2.14 and 2.29, respectively. Fourteen bacterial isolates did not show any proteolytic
activity. Chitinolytic activity varied from 1.24 to 2.67 in different bacterial isolates. Isolates
NNY 18, NNY 52, NNY 73 and GKY 10 showed very little chitinolytic activity. Four isolates,
NNY 23, NNY 43, NNY 34 and NKY 91 showed 2.67, 2.50, 2.40 and 2.50 enzyme production
efficiency, respectively. The bacterial isolates NNY 58, NKY 48 and NKY 69 expressed only
chitinolytic activity. Isolate NKY 66 expressed only proteolytic activity whereas isolates NKY
17, NKY 62 and NKY 79 expressed only lipolytic activity. Twelve bacterial isolates were
found to express all three enzyme activities.
During studies of pathogenic interactions, only 47 bacterial isolates were found to kill the
termites at 5 day of observation. The killing frequency of different bacterial isolates varied from
5.7 to 100 per cent at 5 day. Bacterial isolates NNY 23, NSY 19 and NKY 83 caused 100 per
cent killing of the termites whereas 14 other isolates caused more than 82 per cent killing at 5
day. At 7 days of observation, 100 per cent killing of the termites was observed with four more
bacterial isolates NNY 19, NNY 43, NSY 3 and NKY 91. Bacterial isolate NNY 23 possessed
all the three enzyme activities and caused 100 per cent killing of the termites at 5 day of
observation. Another bacterial isolate NKY 64 which did not show any of the enzyme activity
but it caused 57.8 per cent killing of termites at 5 day. These results indicated that besides the
production of three enzymes, some other metabolites (toxin or siderophore) could also be
contributing to the killing of termites.
Reisolation of bacteria from dead termites showed that seven bacterial isolates viz. NNY
52, NNY 62, NSY 3, NSY 10, NKY 25, NKY 27 and NKY 31 killed even the gut bacteria of
the termites and only colonies of inoculated pathogenic bacteria appeared on nutrient agar, soil
extract agar and KB medium plates. In the study of other termites inoculated with other 16
bacterial isolates, more than two types of colonies were observed on medium plates indicating
that gut bacteria were not killed after ingestion/infection of antagonistic bacteria.
Twenty-one bacterial isolates having more than 80 per cent killing of termites at 7 day of
observation were identified by standard procedures up to genus level as described in Bergey’s
Manual of Determinative Bacteriology. Gram-positive staining was observed only in bacterial
isolates NNY 10, NNY 34, NNY 50, NNY 52, NSY 2, NSY 3, NSY 19, NKY 83, NKY 91 and
GNY 17. Based on the comparative analysis of various morphological (colony morphology,
pigment production and sporulation) and biochemical characteristics (such as indole
production, methyl red test, Voges-Proskauer reaction, citrate utilization, oxidase, catalase and
hydrolysis of starch and cellulose), the antagonistic bacteria were found to belong to the genera
of Arthrobacter, Bacillus, Chromobacterium, Enterobacter, Micrococcus, Neisseria,
Pseudomonas and Serratia.
 
Date 2016-11-23T09:23:15Z
2016-11-23T09:23:15Z
2007
 
Type Thesis
 
Identifier http://krishikosh.egranth.ac.in/handle/1/87156
 
Language en
 
Format application/pdf
 
Publisher CCSHAU