A comparison of ammonia-oxidiser populations in eutrophic and oligotrophic basins of a large freshwater lake

A combination of PCR amplification and oligonucleotide probing was used to investigate the populations of ammonia-oxidisers of the -Proteobacteria in the eutrophic and oligotrophic basins of Lake Windermere, a large temperate lake in the English Lake District. Numbers of ammonia-oxidisers (MPN) in the Windermere lakewater were low (< 100 cells ml^–1) throughout the year with the exception of peaks in August, which coincided with stratification, and November in the South Basin where overturn may have introduced ammonia-oxidising bacteria into the water column. Sediment samples contained larger populations of ammonia oxidisers, usually ca. 10⁴ per g. dry weight, which remained relatively constant throughout the seasonal cycle in both Basins. DNA was recovered from lakewater and sediment samples and Nitrosospiraand N. europaea-eutrophalineage16S rRNA genes amplified in a nested PCR reaction, with confirmation of identity by oligonucleotide hybridisation. Nitrosospira 16S rDNA was readily detected in all samples and therefore found to be ubiquitous. In contrast, nitrosomonad DNA of the N. europaea-eutropha lineage could only be detected in the oligotrophic North Basin. Enrichment cultures of lakewater samples only exhibited nitrification at low (0.67 mM) and medium (5 mM) ammonium concentrations, whilst sediment enrichments nitrified at all concentrations tested including high (12.5 mM) ammonium medium. These data suggest that ammonia-oxidiser populations may be physiologically distinguished between lakewater and sediment, and that species distribution in a single lake is non-uniform.     

Insertion sequence (IS) hybridization supports classification of Rhizobium meliloti by phage typing

Sixty-one isolates of Rhizobium meliloti from two field sites which had been previously classified into 15 phage types on the basis of sensitivity to 16 typing phages, were subjected to insertion sequence (IS) hybridization using DNA probes for ISR m 3 and ISR m 5. Isolates from all but one phage type contained ISR m 3 (apparent copy no. 1–11) and all isolates contained ISR m 5 (apparent copy no. 3–11). The isolates were placed into 24 IS classes based on differences in their respective ISR m 3 and ISR m 5 hybridization profiles. At either field site, isolates representing different phage types possessed IS hybridization profiles that differed from each other, while those comprising a specific type had identical or closely related profiles. Isolates from one phage type were unusual since they did not react with any of the typing phages and were shown by IS hybridization to constitute a heterogeneous group. Evidence for spatial effects were provided by isolates from two of six types present at both sites which fell into separate IS classes on the basis of their site of origin. These data have ecological implications and suggest that for a particular site, phage typing may be employed for the rapid assessment of the genetic diversity among field isolates.     

Diversity of sulfate-reducing bacteria from an extreme hypersaline sediment, Great Salt Lake (Utah)

The diversity of sulfate-reducing bacteria (SRB) inhabiting the extreme hypersaline sediment (270 g L(-1) NaCl) of the northern arm of Great Salt Lake was studied by integrating cultivation and genotypic identification approaches involving PCR-based retrieval of 16S rRNA and dsrAB genes, the latter encoding major subunits of dissimilatory (bi) sulfite reductase. The majority (85%) of dsrAB sequences retrieved directly from the sediment formed a lineage of high (micro) diversity affiliated with the genus Desulfohalobium, while others represented novel lineages within the families Desulfohalobiaceae and Desulfobacteraceae or among Gram-positive SRB. Using the same sediment, SRB enrichment cultures were established in parallel at 100 and at 190 g L(-1) NaCl using different electron donors. After 5-6 transfers, dsrAB and 16S rRNA gene-based profiling of these enrichment cultures recovered a SRB community composition congruent with the cultivation-independent profiling of the sediment. Pure culture representatives of the predominant Desulfohalobium-related lineage and of one of the Desulfobacteraceae-affilated lineages were successfully obtained. The growth performance of these isolates and of the enrichment cultures suggests that the sediment SRB community of the northern arm of Great Salt Lake consists of moderate halophiles, which are salt-stressed at the in situ salinity of 27%.     

Prevalence of IS(Aba1) in epidemiologically unrelated Acinetobacter baumannii clinical isolates

Seventy-five Acinetobacter baumannii strains belonging to different pulsetypes, plus one ceftazidime-susceptible strain, from a pulsetype in which all strains were resistant, were included in this study. The minimum inhibitory concentration of ceftazidime was determined by the microdilution method. The bla(ADC)-like gene, the IS(Aba1) element and the IS(Aba1) located in the bla(ADC)-like promoter were detected by PCR. The objective of the study was to determine the prevalence of IS(Aba1) in a collection of epidemiologically unrelated A. baumannii clinical isolates. The bla(ADC)-like gene was detected in 74 (97.3%) out of the 76 strains analysed. In these 74 strains, 51 (69%) were positive for the IS element and it was not detected in 23 (31%) strains. Among the A. baumannii strains containing the IS element, 40 (78.4%) had the IS element located in the promoter region of the bla(ADC)-like gene. In a high percentage of A. baumannii clinical isolates carrying the IS(Aba1), this is inserted into the promoter region of the bla(ADC)-like gene. In addition, two clinical isolates belonging to the same pulsetype, one with and one without the IS(Aba1), can be found in the clinical setting, suggesting the potential acquisition or loss of this genetic element in the hospital environment.     

Enumeration and Localization of N(2)-Fixing Bacteria Associated with Roots of Spartina alterniflora Loisel

Numbers and possible locations of N(2)-fixing bacteria were investigated in roots of Spartina alterniflora Loisel, which support nitrogenase activity in the undisturbed native habitat. N(2)-fixing bacteria were recovered in cultures both from S. alterniflora roots and from the surrounding sediment, and they formed a greater proportion of the bacteria recovered from root homogenates than from salt-marsh sediment. N(2)-fixing bacteria were recovered in high numbers from the rhizoplane of S. alterniflora after roots were treated with 1 or 5% chloramine-T for 1 h or with 1% NaOCl for 1 or 2 h. Immersing S. alterniflora roots in 5% NaOCl for 1 h was more effective in distinguishing bacteria inside the roots since this treatment nearly eliminated N(2)-fixing bacteria recoverable from the rhizoplane, although high numbers of N(2)-fixing bacteria were recovered from homogenates of roots treated with 5% NaOCl for 1 h. However, this treatment was less effective with roots of Zea mays L. (Funks G4646) and Sorghum bicolor (L.) Moench (CK-60 A), indicating that techniques to surface sterilize roots should be evaluated for different plants. Bacteria were observed by light and electron microscopy inter- and intracellularly in the cortex and in the aerenchyma of S. alterniflora roots. This study clearly shows that bacteria, including N(2) fixers, colonize the interior of roots of S. alterniflora growing in a Chesapeake Bay, Maryland, salt marsh.     

Isolation of an insertion sequence from Ralstonia solanacearum race 1 and its potential use for strain characterization and detection

A new insertion sequence (IS), IS1405, was isolated and characterized from a Ralstonia solanacearum race 1 strain by the method of insertional inactivation of the sacB gene. Sequence analysis indicated that the IS is closely related to the members of IS5 family, but the extent of nucleotide sequence identity in 5' and 3' noncoding regions between IS1405 and other members of IS5 family is only 23 to 31%. Nucleotide sequences of these regions were used to design specific oligonucleotide primers for detection of race 1 strains by PCR. The PCR amplified a specific DNA fragment for all R. solanacearum race 1 strains tested, and no amplification was observed with some other plant-pathogenic bacteria. Analysis of nucleotide sequences flanking IS1405 and additional five endogenous IS1405s that reside in the chromosome of R. solanacearum race 1 strains indicated that IS1405 prefers a target site of CTAR and has two different insertional orientations with respect to this target site. Restriction fragment length polymorphism (RFLP) pattern analysis using IS1405 as a probe revealed extensive genetic variation among strains of R. solanacearum race 1 isolated from eight different host plants in Taiwan. The RFLP patterns were then used to subdivide the race 1 strains into two groups and several subgroups, which allowed for tracking different subgroup strains of R. solanacearum through a host plant community. Furthermore, specific insertion sites of IS1405 in certain subgroups were used as a genetic marker to develop subgroup-specific primers for detection of R. solanacearum, and thus, the subgroup strains can be easily identified through a rapid PCR assay rather than RFLP analysis.     

Bacterial Interspersed Mosaic Elements (Bimes) Are a Major Source of Sequence Polymorphism in Escherichia Coli Intergenic Regions Including Specific Associations with a New Insertion Sequence

A significant fraction of Escherichia coli intergenic DNA sequences is composed of two families of repeated bacterial interspersed mosaic elements (BIME-1 and BIME-2). In this study, we determined the sequence organization of six intergenic regions in 51 E. coli and Shigella natural isolates. Each region contains a BIME in E. coli K-12. We found that multiple sequence variations are located within or near these BIMEs in the different bacteria. Events included excisions of a whole BIME-1, expansion/deletion within a BIME-2 and insertions of non-BIME sequences like the boxC repeat or a new IS element, named IS1397. Remarkably, 14 out of 14 IS1397 integration sites correspond to a BIME sequence, strongly suggesting that this IS element is specifically associated with BIMEs, and thus inserts only in extragenic regions. Unlike BIMEs, IS1397 is not detected in all E. coli isolates. Possible relationships between the presence of this IS element and the evolution of BIMEs are discussed.     

Nitrite reductase genes (nirK and nirS) as functional markers to investigate diversity of denitrifying bacteria in pacific northwest marine sediment communities

Genetic heterogeneity of denitrifying bacteria in sediment samples from Puget Sound and two sites on the Washington continental margin was studied by PCR approaches amplifying nirK and nirS genes. These structurally different but functionally equivalent single-copy genes coding for nitrite reductases, a key enzyme of the denitrification process, were used as a molecular marker for denitrifying bacteria. nirS sequences could be amplified from samples of both sampling sites, whereas nirK sequences were detected only in samples from the Washington margin. To assess the underlying nir gene structure, PCR products of both genes were cloned and screened by restriction fragment length polymorphism (RFLP). Rarefraction analysis revealed a high level of diversity especially for nirS clones from Puget Sound and a slightly lower level of diversity for nirK and nirS clones from the Washington margin. One group dominated within nirK clones, but no dominance and only a few redundant clones were seen between sediment samples for nirS clones in both habitats. Hybridization and sequencing confirmed that all but one of the 228 putative nirS clones were nirS with levels of nucleotide identities as low as 45.3%. Phylogenetic analysis grouped nirS clones into three distinct subclusters within the nirS gene tree which corresponded to the two habitats from which they were obtained. These sequences had little relationship to any strain with known nirS sequences or to isolates (mostly close relatives of Pseudomonas stutzeri) from the Washington margin sediment samples. nirK clones were more closely related to each other than were the nirS clones, with 78.6% and higher nucleotide identities; clones showing only weak hybridization signals were not related to known nirK sequences. All nirK clones were also grouped into a distinct cluster which could not be placed with any strain with known nirK sequences. These findings show a very high diversity of nir sequences within small samples and that these novel nir clusters, some very divergent from known sequences, are not known in cultivated denitrifiers.     

Nucleotide sequence of Rhizobium meliloti insertion sequence ISRm1: homology to IS2 from Escherichia coli and IS426 from Agrobacterium tumefaciens.

Nucleotide sequencing of Rhizobium meliloti insertion sequence ISRm1 showed that it is 1319 nucleotides long and includes 32/31 nucleotide terminal inverted repeats. Analysis of five different insertion sites using sequencing primers complementary to sequences within the left and right ends demonstrated that ISRm1 generates five bp direct repeats at the sites of insertion. Although ISRm1 has shown a target preference for certain short regions (hot spots), there was no apparent similarity in the DNA sequences near the insertion sites. On one strand ISRm1 contains two contiguous open reading frames (ORFs) spanning most of its length. ISRm1 was found to have over 50% sequence homology to insertion sequences IS2 from Escherichia coli and IS426 from Agrobacterium tumefaciens. Their sizes, the sequences of their inverted repeats, and the characteristics of their insertion sites are also comparable, indicating that ISRm1, IS2 and IS426 belong to a class of related insertion sequences. Comparison of the proteins potentially encoded by these insertion sequences showed that the two ORFs found in ISRm1 are also present in IS2 and IS426, suggesting that they may be functional genes.     

Antigenic and genetic variation in influenza A (H1N1) virus isolates recovered from a persistently infected immunodeficient child.

Antigenic and genetic variations have been analyzed in eight consecutive isolates recovered from a child with severe combined immunodeficiency syndrome persistently infected with naturally acquired type A (H1N1) influenza virus over a 10-month period. Hemagglutination inhibition reactions and T1 oligonucleotide fingerprinting demonstrated that these viruses were related to strains causing outbreaks in the United States at that time (1983 to 1984) but that antigenic and genetic differences between consecutive isolates could be detected. This variation between isolates was examined further by sequencing the RNAs encoding the HA1 region of the hemagglutinin (HA) and the nucleoprotein (NP) in five of the consecutive isolates. Multiple point mutations were detected in both genes, and a deletion of one amino acid was detected in the HA. Depending on the isolates compared, 5.8 x 10(-3) to 17 x 10(-3) substitutions per nucleotide site per year were detected in the RNAs encoding the HA1, and 3.5 x 10(-3) to 24 x 10(-3) substitutions per nucleotide site per year were detected in the NP gene. Fifty-four percent of the base changes in the HA1 and 73% in the NP led to amino acid substitutions. A progressive accumulation of mutations over time was not observed, suggesting that the genetic diversity of these viruses may best be interpreted as the result of shifts in the population equilibrium (quasi-species) of replicating variant genomes.     

Distribution of uidA gene sequences in Escherichia coli isolates in water sources and comparison with the expression of beta-glucuronidase activity in 4-methylumbelliferyl-beta-D-glucuronide media.

The uidA gene, which encodes the beta-glucuronidase enzyme, was detected in 97.7% of 435 Escherichia coli isolates from treated and raw water sources by DNA-DNA hybridization; 92.4% of the strains expressed the translational product in 4-methylumbelliferyl-beta-D-glucuronide-containing media after reinoculation. Upon initial isolation from water samples, the minimal medium o-nitrophenyl-beta-D-galactopyranoside-4-methylum-belliferyl -beta-D-glucuronide preparations failed to detect more than 50% of the E. coli isolates that possessed uidA gene. Treated water gave the lowest recovery, with Colilert producing 26% positive samples and Coliquik producing 48% positive samples. There appears to be no relationship between the intensity of the autoradiographic signals of the uidA gene and the expression of beta-glucuronidase activity. Therefore, another variable such as physiological condition of the bacteria could be responsible for the nonexpression of the enzyme activity.     

Histamine-producing bacteria in decomposing skipjack tuna (Katsuwonus pelamis)

Spoilage in skipjack tuna (Katsuwonus pelamis) was studied under controlled conditions by incubating whole, fresh fish in seawater at 38 degrees C, the optimum temperature for histamine formation. Bacterial isolates were obtained from the loin tissue of a decomposing tuna containing 134 mg of histamine per 100 g and a total anaerobic count of 3.5 x 10(5)/g after incubation for 24 h. Over 92% of the 134 isolates obtained were facultatively or obligately anaerobic bacteria. Eighteen isolates produced histamine in culture media containing histidine, and these were identified as Clostridium perfringens, Enterobacter aerogenes, Klebsiella pneumoniae, Proteus mirabilis, and Vibrio alginolyticus. Histidine decarboxylase activity of several isolates was measured in a tuna broth medium and with resting cells suspended in a buffered histidine solution.     

Isolation and 16S rRNA sequence analysis of the beneficial bacteria from the rhizosphere of rice

The present study deals with the isolation of plant growth promoting rhizobacteria (PGPR) from rice (variety NIAB IRRI-9) and the beneficial effects of these inoculants on two Basmati rice varieties. Nitrogen-fixing activity (acetylene-reduction activity) was detected in the roots and submerged shoots of field-grown rice variety NIAB IRRI-9. Estimation of the population size of diazotrophic bacteria by ARA-based MPN (acetylene reduction assay-based most probable number) in roots and shoots indicated about 10(5)-10(6) counts/g dry weight at panicle initiation and grain filling stages. Four bacterial isolates from rice roots and shoots were obtained in pure culture which produced phytohormone indoleacetic acid (IAA) in the growth medium. Among these, three isolates S1, S4, and R3 reduced acetylene to ethylene in nitrogen-free semi-solid medium. Morphological and physiological characteristics of the isolates indicated that three nitrogen-fixing isolates S1, S4, and R3 belonged to the genus Enterobacter, while the non-fixing isolate R8 belonged to the genus Aeromonas. 16S rRNA sequence of one isolate from root (R8) and one isolate from shoot (S1) was obtained which confirmed identification of the isolates as Aeromonas veronii and Enterobacter cloacae, respectively. The 1517-nucleotide-long sequence of the isolate R8 showed 99% similarity with Aeromonas veronii (accession No. AF099023) while partial 16S rRNA sequence (two stretches of total 1271 nucleotide length) of S1 showed 97% similarity with the sequence of Enterobacter cloacae (accession No. AJ251469). The seedlings of two rice varieties Basmati 385 and Super Basmati were inoculated with the four bacterial isolates from rice and one Azospirillum brasilense strain Wb3, which was isolated from wheat. In the rice variety Basmati 385, maximum increase in root area and plant biomass was obtained in plants inoculated with Enterobacter S1 and Azospirillum Wb3, whereas in the rice variety Super Basmati, inoculation with Enterobacter R3 resulted in maximum increase of root area and plant biomass. Nitrogen fixation was quantified by using 15N isotopic dilution method. Maximum fixation was observed in Basmati 385 with the inoculants Azospirillum Wb3 and Enterobacter S1 where nearly 46% and 41% of the nitrogen was derived from atmosphere (%Ndfa), respectively. In general, higher nitrogen fixation was observed in variety Basmati 385 than in Super Basmati, and different bacterial strains were found more effective as inoculants for the rice varieties Basmati 385 and Super Basmati.     

The role of bla(OXA-like carbapenemase) and their insertion sequences (ISS) in the induction of resistance against carbapenem antibiotics among Acinetobacter baumannii isolates in Tehran hospitals

This study aimed to evaluate the occurrence and dissemination of bla(OXA-like) carbapenemase genes and their insertion sequences among Acinetobacter baumannii isolates, taken from different hospitals in Tehran city and also their roles in the induction of resistance to carbapenem drugs. A total number of 100 non duplicate Acinetobacter baumannii with different origins, were isolated from patients with proved nosocomial infections at eight university hospital in Tehran city. Antimicrobial susceptibility of these strains was done by E-test against 7 antimicrobial agents according to CLSI guideline. PCR of bla(OXA-51-like), bla(OXA-23-like), bla(OXA-24-like), bla(OXA-58-like), IS(ABA-1), IS(1133) was carried out by specialized primers and then these strains were typed by REP-fingerprinting. Colistin, imipenem and meropenem were the most sensitive antibiotics against Acinetobacter baumannii isolates with 96%, 51% and 51% sensitivity respectively. All the isolates had a bla(OXA-51-like) intrinsic to these species. The rates of bla(OXA-23), 23 and 58-like were 38%, 32% and 1% respectively. Coexistence of bla(OXA-51/23/24-like) was observed among 16% of these isolates. All bla(OXA-23-like) carbapenemase genes had only one IS(ABA1). REP fingerprinting showed 5 genotypes among carbapenem resistant isolates, 16 of them being genotype A. This study emphasized on the major role of bla(OXA-like) carbapenemase, particularly bla(OXA-23-like) carbapenemase and their IS(ABA1), in the dissemination of carbapenem resistant Acinetobacter baumannii. This study confirmed a presumptive role of IS element neighboring the carbapenemase gene in the elevation of resistance to carbapenem drug among Acinetobacter baumannii isolates for the first time in Iran.     

先锋牧草-香根草联合固氮菌多样性

[目的]香根草(Vetiver zizanioides)是一种多年生禾本科草本植物,具有极强的生态适应性和抗逆能力,可作饲料和水土保持用.通过研究香根草联合固氮菌多样性,为进一步研究和应用打下基础.[方法]采用无氮培养基,首次从香根草中分离到47株联合固氮菌,分别应用SDS-PAGE全细胞蛋白质电泳、DNA指纹图谱、唯一碳源和16S rDNA全序列测定等方法,进行聚类和多样性分析.[结果]SDS-PAGE、IS-PCR和Bio-BIQA碳源利用的聚类结果基本一致,将供试菌株分为6个类群和4个单菌株;16S rDNA序列测定表明,从香根草中分离的菌株包括了佛莱辛草螺菌(Herbaspirillum frisingense)、中型假食酸菌(Pseudacidovorax intermedius)、恶臭假单胞菌(Pseudomonas putida)、荧光假单胞菌(Pseudomonas fluorescens)、越南伯克氏菌(Burkholderia vietnamiensis)、阴沟肠杆菌(Enterobacter cloacae)、路德维希肠杆菌(Enterobacter ludwigii)和松江壳聚糖降解菌(Mitsuaria chitosanitabida)等不同菌种.[结论]香根草联合固氮菌具有较大的资源多样性,对固氮菌资源的扩展和将来牧草上的应用具有重要意义.     

先锋牧草-香根草联合固氮菌多样性研究

摘要：【目的】香根草（Vetiver zizanioides）是一种多年生禾本科草本植物,具有极强的生态适应性和抗逆能力,可作饲料和水土保持用。通过研究香根草联合固氮菌多样性,为进一步研究和应用打下基础。【方法】采用无氮培养基,首次从香根草中分离到47株联合固氮菌,分别应用SDS-PAGE全细胞蛋白质电泳、DNA指纹图谱、唯一碳源和16S rDNA全序列测定等方法,进行聚类和多样性分析。【结果】SDS-PAGE、IS-PCR和Bio-BIQA碳源利用的聚类结果基本一致,将供试菌株分为6个类群和4个单菌株;     

Sedimentation in a large lake: the importance of fluctuations in water level

1. A sediment trap study was conducted in the central basin of Lower Lough Erne, Northern Ireland.
2. The material caught was low in organic matter, ash weight was 77% of dry weight on average.
3. Mass deposition of material was shown to be correlated with lake water level. When lake water level fell or rose above the middle range, the amount of material caught by the trap increased markedly. The effect was exaggerated by an unusually dry summer in 1995 which caused abnormally low water levels in the lake.
4. Comparison of Erne data with Windermere shows similar deposition rate of many substances, but the deposition rate of iron is thirteen times higher in Erne than in Windermere, and iron made up 39% of the ash weight in the Erne trap data.
5. Only 17% of the silica removed from the water column during diatom growth was recovered in the trap over the same time period.
6. Trap data are compared with historical data for sediment deposition and the implications of sediment focusing are discussed.     

Multiple copies of IS10 in the Enterobacter cloacae MD36 chromosome.

Repetitive sequences were isolated and characterized as double-stranded DNA fragments by treatment with S1 nuclease after denaturation and renaturation of the total DNA of Enterobacter cloacae MD36. One repetitive sequence was identical to the nucleotide sequence of IS10-right (IS10R), which is the active element in the plasmid-associated transposon Tn10. Unexpectedly, 15 copies of IS10R were found in the chromosomal DNA of E. cloacae MD36. One copy of the central region of Tn10 was found in the total DNA of E. cloacae MD36. IS10Rs in restriction fragments isolated from the E. cloacae MD36 total DNA showed 9-bp duplications adjacent to the terminal sequences that are characteristic of Tn10 transposition. This result suggests that many copies of IS10R in E. cloacae MD36 are due to transposition of IS10R alone, not due to transposition of Tn10 or to DNA rearrangement. I also found nine copies of IS10 in Shigella sonnei HH109, two and four copies in two different natural isolates of Escherichia coli, and two copies in E. coli K-12 strain JM109 from the 60 bacterial strains that were examined. All dam sites in the IS10s in E. cloacae MD36 and S. sonnei HH109 were methylated. Tn10 and IS10 transpose by a mechanism in which the element is excised from the donor site and inserted into the new target site without significant replication of the transposing segment; thus, the copy numbers of the elements in the cell are thought to be unchanged in most circumstances. Accumulation of IS10 copies in E. cloacae MD36 has interesting evolutionary implications.     

Isolation of pathogenic bacteria from <Emphasis Type="Italic">Oberea linearis</Emphasis> (Coleptera: Cerambycidae)

The bacterial flora of the Oberea linearis (Coleoptera: Cerambycidae) was investigated and 13 different bacteria were isolated from O. linearis larvae. Seven of these bacteria were performed and characterized at species level and the rest of them were characterized at genus level. In this study, we determined morphological and physiological characteristics of the bacterial isolates by conventional and routine techniques, biochemical properties and metabolic enzyme profiles by API20E and Phoenix 1000A panel test systems. Additionally, 16S rRNA gene sequence analysis was also performed to identify the isolates at the molecular level. The isolates were identified as Acinetobacter calcoaceticus (Ol1), Enterobacter aerogenes (Ol2), Pseudomonas sp. (Ol3), Flavobacterium sp. (Ol4), Microbacterium sp. (Ol5), Enterobacter agglomerans (Ol6), Xanthomonas sp. (Ol7), Pseudomonas syringae (Ol8), Pseudomonas sp. (Ol9), Xanthomonas sp. (Ol10), Enterobacter cancerogenus (Ol11), Xanthomonas maltophilia (Ol12), and Serratia marcescens (Ol13). This is the first record of bacterial isolates (Ol5, Ol8, Ol11, Ol12) from any insect. All these bacteria were tested against O. linearis larvae, and Serratia marcescens was found to cause the highest mortality (65%). On the other hand, we determined 90% mortality against this pest within four days by utilizing spore and crystal mixture of Bacillus thuringiensis isolated from Melolontha melolontha.