Showing papers on "Chitinase published in 2010"

Chitins and chitosans as immunoadjuvants and non-allergenic drug carriers.

Abstract: Due to the fact that some individuals are allergic to crustaceans, the presumed relationship between allergy and the presence of chitin in crustaceans has been investigated. In vivo, chitin is part of complex structures with other organic and inorganic compounds: in arthropods chitin is covalently linked to proteins and tanned by quinones, in fungi it is covalently linked to glucans, while in bacteria chitin is diversely combined according to Gram(+/-) classification. On the other hand, isolated, purified chitin is a plain polysaccharide that, at the nano level, presents itself as a highly associated structure, recently refined in terms of regularity, nature of bonds, crystallinity degree and unusual colloidal behavior. Chitins and modified chitins exert a number of beneficial actions, i.e., (i) they stimulate macrophages by interacting with receptors on the macrophage surface that mediate the internalization of chitin particles to be degraded by lysozyme and N-acetyl-beta-glucosaminidase (such as Nod-like, Toll-like, lectin, Dectin-1, leukotriene 134 and mannose receptors); (ii) the macrophages produce cytokines and other compounds that confer non-specific host resistance against bacterial and viral infections, and anti-tumor activity; (iii) chitin is a strong Th1 adjuvant that up-regulates Th1 immunity induced by heat-killed Mycobacterium bovis, while down- regulating Th2 immunity induced by mycobacterial protein; (iv) direct intranasal application of chitin microparticles into the lung was also able to significantly down-regulate allergic response to Dermatophagoids pteronyssinus and Aspergillus fumigatus in a murine model of allergy; (v) chitin microparticles had a beneficial effect in preventing and treating histopathologic changes in the airways of asthmatic mice; (vi) authors support the fact that chitin depresses the development of adaptive type 2 allergic responses. Since the expression of chitinases, chitrotriosidase and chitinase-like proteins is greatly amplified during many infections and diseases, the common feature of chitinase-like proteins and chitinase activity in all organisms appears to be the biochemical defense of the host. Unfortunately, conceptual and methodological errors are present in certain recent articles dealing with chitin and allergy, i.e., (1) omitted consideration of mammalian chitinase and/or chitotriosidase secretion, accompanied by inactive chitinase-like proteins, as an ancestral defensive means against invasion, capable to prevent the insurgence of allergy; (2) omitted consideration of the fact that the mammalian organism recognizes more promptly the secreted water soluble chitinase produced by a pathogen, rather than the insoluble and well protected chitin within the pathogen itself; (3) superficial and incomplete reports and investigations on chitin as an allergen, without mentioning the potent allergen from crustacean flesh, tropomyosine; (4) limited perception of the importance of the chemical/biochemical characteristics of the isolated chitin or chitosan for the replication of experiments and optimization of results; and (5) lack of interdisciplinarity. There is quite a large body of knowledge today on the use of chitosans as biomaterials, and more specifically as drug carriers for a variety of applications: the delivery routes being the same as those adopted for the immunological studies. Said articles, that devote attention to the safety and biocompatibility aspects, never reported intolerance or allergy in individuals and animals, even when the quantities of chitosan used in single experiments were quite large. Therefore, it is concluded that crab, shrimp, prawn and lobster chitins, as well as chitosans of all grades, once purified, should not be considered as "crustacean derivatives", because the isolation procedures have removed proteins, fats and other contaminants to such an extent as to allow them to be classified as chemicals regardless of their origin.

Insect chitinase and chitinase-like proteins

Abstract: Insect chitinases belong to family 18 glycosylhydrolases that hydrolyze chitin by an endo-type of cleavage while retaining the anomeric β-(1→4) configuration of products. There are multiple genes encoding chitinases and chitinase-like proteins in all insect species studied using bioinformatics searches. These chitinases differ in size, domain organization, physical, chemical and enzymatic properties, and in patterns of their expression during development. There are also differences in tissue specificity of expression. Based on a phylogenetic analysis, insect chitinases and chitinase-like proteins have been classified into several different groups. Results of RNA interference experiments demonstrate that at least some of these chitinases belonging to different groups serve non-redundant functions and are essential for insect survival, molting or development. Chitinases have been utilized for biological control of insect pests on transgenic plants either alone or in combination with other insecticidal proteins. Specific chitinases may prove to be useful as biocontrol agents and/or as vaccines.

Sequence and structural analysis of the chitinase insertion domain reveals two conserved motifs involved in chitin-binding.

Abstract: Background Chitinases are prevalent in life and are found in species including archaea, bacteria, fungi, plants, and animals. They break down chitin, which is the second most abundant carbohydrate in nature after cellulose. Hence, they are important for maintaining a balance between carbon and nitrogen trapped as insoluble chitin in biomass. Chitinases are classified into two families, 18 and 19 glycoside hydrolases. In addition to a catalytic domain, which is a triosephosphate isomerase barrel, many family 18 chitinases contain another module, i.e., chitinase insertion domain. While numerous studies focus on the biological role of the catalytic domain in chitinase activity, the function of the chitinase insertion domain is not completely understood. Bioinformatics offers an important avenue in which to facilitate understanding the role of residues within the chitinase insertion domain in chitinase function. Results Twenty-seven chitinase insertion domain sequences, which include four experimentally determined structures and span five kingdoms, were aligned and analyzed using a modified sequence entropy parameter. Thirty-two positions with conserved residues were identified. The role of these conserved residues was explored by conducting a structural analysis of a number of holo-enzymes. Hydrogen bonding and van der Waals calculations revealed a distinct subset of four conserved residues constituting two sequence motifs that interact with oligosaccharides. The other conserved residues may be key to the structure, folding, and stability of this domain. Conclusions Sequence and structural studies of the chitinase insertion domains conducted within the framework of evolution identified four conserved residues which clearly interact with the substrates. Furthermore, evolutionary studies propose a link between the appearance of the chitinase insertion domain and the function of family 18 chitinases in the subfamily A.

Thermal stability of thaumatin-like protein, chitinase, and invertase isolated from Sauvignon blanc and Semillon juice and their role in haze formation in wine.

Abstract: A thermal unfolding study of thaumatin-like protein, chitinase, and invertase isolated from Vitis vinifera Sauvignon blanc and Semillon juice was undertaken. Differential scanning calorimetry demonstrated that chitinase was a major player in heat-induced haze in unfined wines as it had a low melt temperature, and aggregation was observed. The kinetics of chitinase F1 (Sauvignon blanc) unfolding was studied using circular dichroism spectrometry. Chitinase unfolding conforms to Arrhenius behavior having an activation energy of 320 kJ/mol. This enabled a predictive model for protein stability to be generated, predicting a half-life of 9 years at 15 °C, 4.7 days at 30 °C, and 17 min at 45 °C. Circular dichroism studies indicate that chitinase unfolding follows three steps: an initial irreversible step from the native to an unfolded conformation, a reversible step between a collapsed and an unfolded non-native conformation, followed by irreversible aggregation associated with visible haze formation.

Chitin Biochemistry: Synthesis, Hydrolysis and Inhibition

Abstract: Chitin is an abundant extracellular amino-sugar polymer that in association with other external biomacromolecules (carbohydrates, proteins) is an essential structural component in forming cell walls in fungi as well as exoskeletons and peritrophic membranes in arthropods. Chitin synthesis and degradation in insects are cyclical dynamic events, and since being crucial for facilitating growth and development, are strictly coordinated and regulated. Chitin formation and hydrolysis are complex, multi-faceted, interconnected and highly harmonized intracellular and extracellular cascades of biochemical and biophysical transformations. The list of processes, many of which are still poorly understood, include transcriptional, translational and post-translational modifications relative to the catalytic machinery; cellular movement of clustered catalytic units to and their eventual fixed spatial integration into plasma membranes; chitin polymerization and translocation of polymers across the cell membrane barrier; coalescence of nascent external chitin chains forming crystallites that subsequently associate with assorted proteins to form fibrillar supramacromolecular structures. Cloned and sequenced genes encoding the anabolic chitin synthase, and the catabolic chitinase, β- N -acetylglucosaminidase and chitin deacetylase combined with purification and characterization of the expressed enzymes as well as crystallographic and inhibition studies were instrumental in elucidating the intricate mechanisms of catalysis relative to chitin polymerization and degradation. The powerful tools of RNAi knockout methodologies were harnessed for functional analysis of a variety of chitin-related genes. Chitin research carries practical aspect as the physiologically crucial synthesis and hydrolysis of the polymer have been regarded as suitable, attractive and largely selective targets for interference and for producing effective pharmaceuticals and safe biopesticides.

Melanin Externalization in Candida albicans Depends on Cell Wall Chitin Structures

Abstract: The fungal pathogen Candida albicans produces dark-pigmented melanin after 3 to 4 days of incubation in medium containing l-3,4-dihydroxyphenylalanine (l-DOPA) as a substrate. Expression profiling of C. albicans revealed very few genes significantly up- or downregulated by growth in l-DOPA. We were unable to determine a possible role for melanin in the virulence of C. albicans. However, we showed that melanin was externalized from the fungal cells in the form of electron-dense melanosomes that were free or often loosely bound to the cell wall exterior. Melanin production was boosted by the addition of N-acetylglucosamine to the medium, indicating a possible association between melanin production and chitin synthesis. Melanin externalization was blocked in a mutant specifically disrupted in the chitin synthase-encoding gene CHS2. Melanosomes remained within the outermost cell wall layers in chs3Delta and chs2Delta chs3Delta mutants but were fully externalized in chs8Delta and chs2Delta chs8Delta mutants. All the CHS mutants synthesized dark pigment at equivalent rates from mixed membrane fractions in vitro, suggesting it was the form of chitin structure produced by the enzymes, not the enzymes themselves, that was involved in the melanin externalization process. Mutants with single and double disruptions of the chitinase genes CHT2 and CHT3 and the chitin pathway regulator ECM33 also showed impaired melanin externalization. We hypothesize that the chitin product of Chs3 forms a scaffold essential for normal externalization of melanosomes, while the Chs8 chitin product, probably produced in cell walls in greater quantity in the absence of CHS2, impedes externalization.

Production of cuticle degrading enzymes by Isaria fumosorosea and their evaluation as a biocontrol agent against diamondback moth

Abstract: Production and biocontrol efficacy of culture filtrates containing cuticle degrading enzymes from three isolates of Isaria fumosorosea against diamondback moth (Plutella xylostella) was observed during this study. This fungus when cultured in liquid medium having different carbon sources showed maximum biomass production when 1% chitin was added as carbon source. These isolates when grown in liquid culture conditions having 1% chitin as source produced cuticular degrading enzymes (proteases (Pr1 and Pr2), chitinases, chitosanase, and lipase) in a sequential manner and the production of these enzymes differed from control. Biocontrol assays with P. xylostella showed that the culture filtrates of I. fumosorosea were potent antifeedants because reduction in the feeding rate and body weight of the larvae was observed. Similarly, reduction in rates of successful pupation, adult emergence was observed when the culture filtrates were applied topically. At the end of the test period, the lowest ST50 value (1.57 ± 0.20 days) was recorded for insect groups treated with culture filtrates from isolate IF28.2 when compared to the control. In view of the need for safer and environmentally friendly pest management tools, the present study can help in the development of enzyme-based biopesticides against P. xylostella.

Comparative Molecular Evolution of Trichoderma Chitinases in Response to Mycoparasitic Interactions

Abstract: Certain species of the fungal genus Trichoderma are potent mycoparasites and are used for biological control of fungal diseases on agricultural crops In Trichoderma, whole-genome sequencing reveal between 20 and 36 different genes encoding chitinases, hydrolytic enzymes that are involved in the mycoparasitic attack Sequences of Trichoderma chitinase genes chi18-5, chi18-13, chi18-15 and chi18-17, which all exhibit specific expression during mycoparasitism-related conditions, were determined from up to 13 different taxa and studied with regard to their evolutionary patterns Two of them, chi18-13 and chi18-17, are members of the B1/B2 chitinase subgroup that have expanded significantly in paralog number in mycoparasitic Hypocrea atroviridis and H virens Chi18-13 contains two codons that evolve under positive selection and seven groups of co-evolving sites Chi18-15 displays a unique codon-usage and contains five codons that evolve under positive selection and three groups of co-evolving sites Regions of high amino acid variability are preferentially localized to substrate- or product side of the catalytic clefts Differences in amino acid diversity/conservation patterns between different Trichoderma clades are observed These observations show that Trichoderma chitinases chi18-13 and chi18-15 evolve in a manner consistent with rapid co-evolutionary interactions and identifies putative target regions involved in determining substrate-specificity

An antifungal chitinase produced by Bacillus subtilis using chitin waste as a carbon source.

Abstract: The production of inexpensive chitinolytic enzymes is an element in the utilization of shellfish-processing waste. In this study, shrimp and crab shell powder, prepared by treating shrimp- and crab-processing waste by boiling and crushing, was used as a substrate for the isolation of an antifungal chitinase-producing microorganism. Bacillus subtilis NPU 001, a strain isolated from soil samples, excreted a chitinase when cultured in a medium containing 2% (w/v) shrimp and crab shell powder as the major carbon source. The chitinase, which was purified by sequential chromatography, had a Mw of 31 kDa and a pI of 5.4. The purified chitinase (2 mg ml−1) inhibited hyphal extension of the fungus Fusarium oxysporum. Compared with other known bacterial chitinases, the unique characteristics of NPU 001 chitinase include antifungal activity against plant-pathogenic fungi and the production of chitotriose as the major enzymatic hydrolysate from colloidal chitin.

Evolution, Homology Conservation, and Identification of Unique Sequence Signatures in GH19 Family Chitinases

Abstract: The discovery of GH (Glycoside Hydrolase) 19 chitinases in Streptomyces sp. raises the possibility of the presence of these proteins in other bacterial species, since they were initially thought to be confined to higher plants. The present study mainly concentrates on the phylogenetic distribution and homology conservation in GH19 family chitinases. Extensive database searches are performed to identify the presence of GH19 family chitinases in the three major super kingdoms of life. Multiple sequence alignment of all the identified GH19 chitinase family members resulted in the identification of globally conserved residues. We further identified conserved sequence motifs across the major sub groups within the family. Estimation of evolutionary distance between the various bacterial and plant chitinases are carried out to better understand the pattern of evolution. Our study also supports the horizontal gene transfer theory, which states that GH19 chitinase genes are transferred from higher plants to bacteria. Further, the present study sheds light on the phylogenetic distribution and identifies unique sequence signatures that define GH19 chitinase family of proteins. The identified motifs could be used as markers to delineate uncharacterized GH19 family chitinases. The estimation of evolutionary distance between chitinase identified in plants and bacteria shows that the flowering plants are more related to chitinase in actinobacteria than that of identified in purple bacteria. We propose a model to elucidate the natural history of GH19 family chitinases.

Contributions of Francisella tularensis subsp. novicida Chitinases and Sec Secretion System to Biofilm Formation on Chitin

Abstract: Francisella tularensis, the zoonotic cause of tularemia, can infect numerous mammals and other eukaryotes. Although studying F. tularensis pathogenesis is essential to comprehending disease, mammalian infection is just one step in the ecology of Francisella species. F. tularensis has been isolated from aquatic environments and arthropod vectors, environments in which chitin could serve as a potential carbon source and as a surface for attachment and growth. We show that F. tularensis subsp. novicida forms biofilms during the colonization of chitin surfaces. The ability of F. tularensis to persist using chitin as a sole carbon source is dependent on chitinases, since mutants lacking chiA or chiB are attenuated for chitin colonization and biofilm formation in the absence of exogenous sugar. A genetic screen for biofilm mutants identified the Sec translocon export pathway and 14 secreted proteins. We show that these genes are important for initial attachment during biofilm formation. We generated defined deletion mutants by targeting two chaperone genes (secB1 and secB2) involved in Sec-dependent secretion and four genes that encode putative secreted proteins. All of the mutants were deficient in attachment to polystyrene and chitin surfaces and for biofilm formation compared to wild-type F. novicida. In contrast, mutations in the Sec translocon and secreted factors did not affect virulence. Our data suggest that biofilm formation by F. tularensis promotes persistence on chitin surfaces. Further study of the interaction of F. tularensis with the chitin microenvironment may provide insight into the environmental survival and transmission mechanisms of this pathogen.

Chitinases from the black tiger shrimp Penaeus monodon: Phylogenetics, expression and activities

Abstract: Chitinases are essential enzymes for crustaceans and animal alike for their molting and digestion of foods containing chitin. From the Penaeus monodon EST database, cDNA contigs and singletons for three chitinases, namely PmChi1, 2 and 3, were identified. The complete sequences for the mature PmChi1, 3 and partial PmChi2 were amplified and cloned. The reading frames of PmChi1 and 3 encoded mature proteins of 644 and 468 amino acids with calculated molecular masses of 72.4 and 51.9 kDa, respectively. The amino acid sequence comparison among the penaeid chitinases revealed homology around 90%. Therefore, they were grouped together along with those of other crustaceans and insects into three groups separated from those of mammals. PmChi1, 2 and 3 were expressed mainly in hepatopancreas, gill and hepatopancreas, respectively, though small amounts were expressed in other tissues. After molting, only the expression of PmChi2 was down-regulated, while the expression of PmChi1 and 3 was relatively unchanged. The results suggested that the PmChi2 was likely involved in molting while the others might function in the digestion of chitinous foods. The recombinant PmChi1 (rPmChi1) over-produced from Escherichia coli had its optimal pH 5 but it was most stable at neutral pH. Interestingly, the optimal temperature was relatively high at 55 °C. Nevertheless, it was stable at lower temperature below 40 °C. The rPmChi1 preferentially hydrolyzed the more soluble substrates like partially N-acetylated chitin (PNAC) and colloidal chitin from shrimp shell as compared to the β-chitin from squid pen.

Novel β - N -acetylglucosaminidases from Vibrio harveyi 650 : Cloning, expression, enzymatic properties, and subsite identification

Abstract: Since chitin is a highly abundant natural biopolymer, many attempts have been made to convert this insoluble polysaccharide into commercially valuable products using chitinases and β-N-acetylglucosaminidases (GlcNAcases). We have previously reported the structure and function of chitinase A from Vibrio harveyi 650. This study t reports the identification of two GlcNAcases from the same organism and their detailed functional characterization. The genes encoding two new members of family-20 GlcNAcases were isolated from the genome of V. harveyi 650, cloned and expressed at a high level in E. coli. Vh Nag1 has a molecular mass of 89 kDa and an optimum pH of 7.5, whereas Vh Nag2 has a molecular mass of 73 kDa and an optimum pH of 7.0. The recombinant GlcNAcases were found to hydrolyze all the natural substrates, Vh Nag2 being ten-fold more active than Vh Nag1. Product analysis by TLC and quantitative HPLC suggested that Vh Nag2 degraded chitooligosaccharides in a sequential manner, its highest activity being with chitotetraose. Kinetic modeling of the enzymic reaction revealed that binding at subsites (-2) and (+4) had unfavorable (positive) binding free energy changes and that the binding pocket of Vh Nag2 contains four GlcNAc binding subsites, designated (-1),(+1),(+2), and (+3). Two novel GlcNAcases were identified as exolytic enzymes that degraded chitin oligosaccharides, releasing GlcNAc as the end product. In living cells, these intracellular enzymes may work after endolytic chitinases to complete chitin degradation. The availability of the two GlcNAcases, together with the previously-reported chitinase A from the same organism, suggests that a systematic development of the chitin-degrading enzymes may provide a valuable tool in commercial chitin bioconversion.

Two chitinase-like proteins abundantly accumulated in latex of mulberry show insecticidal activity

Abstract: Plant latex is the cytoplasm of highly specialized cells known as laticifers, and is thought to have a critical role in defense against herbivorous insects Proteins abundantly accumulated in latex might therefore be involved in the defense system We purified latex abundant protein a and b (LA-a and LA-b) from mulberry (Morus sp) and analyzed their properties LA-a and LA-b have molecular masses of approximately 50 and 46 kDa, respectively, and are abundant in the soluble fraction of latex Western blotting analysis suggested that they share sequence similarity with each other The sequences of LA-a and LA-b, as determined by Edman degradation, showed chitin-binding domains of plant chitinases at the N termini These proteins showed small but significant chitinase and chitosanase activities Lectin RCA120 indicated that, unlike common plant chitinases, LA-a and LA-b are glycosylated LA-a and LA-b showed insecticidal activities when fed to larvae of the model insect Drosophila melanogaster Our results suggest that the two LA proteins have a crucial role in defense against herbivorous insects, possibly by hydrolyzing their chitin

Degradation of fungal cell walls of phytopathogenic fungi by lytic enzyme of Streptomyces griseus.

Abstract: In vitro tests of interactions between Streptomyces griseus strains and some soil-borne plant pathogens (Fusarium oxysporum, Alternaria alternate, Rhizoctonia solani and Fusarium solani) and 2 isolates of Aspergillus flavus were studied on PDA medium. Strains tested produced a metabolite that inhibited growth of plant pathogenic fungi on PDA medium (dual culture test). When grown in liquid medium having fungal cell walls as sole carbon source, S. griseus produced chitinase enzyme in the medium. Higher levels of this enzyme were induced by cell wall ofAspergillus flavus and the crude chitinase enzyme extracted showed zone of inhibition on all pathogens inoculated PDA plates at all tested concentrations. When lytic enzyme produced by S. griseus was incubated with hyphal wall of the test fungi treated with 2 M NaOH and chloropharm: Methanol, the release of glucose and N acetyl glucosamine significantly increased relative to the untreated one. This result suggests that proteins in the cell walls of pathogens may make these walls more resistant to degradation by the extracellular lytic enzymes. Ionic strength of NaOH on lytic activity was tested, where as the enzymes lysed fungal cell wall best at ionic concentration of 2 M treatment. Pretreatment with alkali or proteolytic enzyme increases their susceptibility for lysis. In vitro lytic activity provides an appropriate condition and the effect of biocontrol organism in field level treatment. Key words: Chitinase enzyme, dual culture test, plant pathogenic fungi, NaOH treatment and Ionic strength.

Chitin Utilization by the Insect-Transmitted Bacterium Xylella fastidiosa

Abstract: Xylella fastidiosa is an insect-borne bacterium that colonizes xylem vessels of a large number of host plants, including several crops of economic importance. Chitin is a polysaccharide present in the cuticle of leafhopper vectors of X. fastidiosa and may serve as a carbon source for this bacterium. Biological assays showed that X. fastidiosa reached larger populations in the presence of chitin. Additionally, chitin induced phenotypic changes in this bacterium, notably increasing adhesiveness. Quantitative PCR assays indicated transcriptional changes in the presence of chitin, and an enzymatic assay demonstrated chitinolytic activity by X. fastidiosa. An ortholog of the chitinase A gene (chiA) was identified in the X. fastidiosa genome. The in silico analysis revealed that the open reading frame of chiA encodes a protein of 351 amino acids with an estimated molecular mass of 40 kDa. chiA is in a locus that consists of genes implicated in polysaccharide degradation. Moreover, this locus was also found in the genomes of closely related bacteria in the genus Xanthomonas, which are plant but not insect associated. X. fastidiosa degraded chitin when grown on a solid chitin-yeast extract-agar medium and grew in liquid medium with chitin as the sole carbon source; ChiA was also determined to be secreted. The gene encoding ChiA was cloned into Escherichia coli, and endochitinase activity was detected in the transformant, showing that the gene is functional and involved in chitin degradation. The results suggest that X. fastidiosa may use its vectors' foregut surface as a carbon source. In addition, chitin may trigger X. fastidiosa's gene regulation and biofilm formation within vectors. Further work is necessary to characterize the role of chitin and its utilization in X. fastidiosa.

Fungal Exposure Modulates the Effect of Polymorphisms of Chitinases on Emergency Department Visits and Hospitalizations

Abstract: Rationale: Chitinases are enzymes that cleave chitin, which is present in fungal cells. Two types of human chitinases, chitotriosidase and acidic mammalian chitinase, and the chitinase-like protein, YKL-40, seem to play an important role in asthma. We hypothesized that exposure to environmental fungi may modulate the effect of chitinases in individuals with asthma.Objectives: To explore whether interactions between high fungal exposure and common genetic variants in the two chitinases in humans, CHIT1 and CHIA, and the chitinase 3-like 1 gene, CHI3L1, are associated with severe asthma exacerbations and other asthma-related outcomes.Methods: Forty-eight single nucleotide polymorphisms (SNPs) in CHIT1, CHIA, and CHI3L1 and one CHIT1 duplication were genotyped in 395 subjects and their parents as part of the Childhood Asthma Management Program. Household levels of mold (an index of fungal exposure) were determined on house dust samples. We conducted family-based association tests with gene–environment intera...

Chitinolytic Bacteria Isolated from Chili Rhizosphere: Chitinase Characterization and Its Application as Biocontrol for Whitefly (Bemisia tabaci Genn.)

Abstract: Problem statement: Chitin, a common constituent of insect exoskeleton, could be hydrolyzed by chitinase. The research was conducted to screen chitinolytic rhizobacteria isolated from rhizosphere of chilli pepper and to determine their chitinase activity in degrading chitin of whitefly, Bemisia tabaci Genn. (Hemiptera: Aleyrodidae). Whitefly is recognized as an important pest on many crops including chilli pepper. Approach: Screening and molecular identification based on 16S rRNA sequence of chitinolytic isolates, chitinase productions, measurement of chitinase activity, characterization of chitinase and effect of the chitinase treatment on whitefly were studied. Results: A total of 25 isolates of rhizobacteria formed a clear zone on solid chitin media. Two isolates, i.e., I.5 and I.21 isolates had the highest chitinolytic index. Based on sequence of 16S rRNA gene, the isolates of I.5 and I.21 were identified as Bacillus sp. and Bacillus cereus, respectively. The highest chitinolytic index and specific activity of I.5 isolate was 0.94 and 0.11 U mg-1 proteins, respectively. Maximum production of I.5 chitinase was occured after 36 h cultivation at 30°C and pH 7.0. The highest chitinolytic index and specific activity of I.21isolate was 0.75 and 0.114 U mg-1 proteins, respectively. Maximum production of I.21 chitinase was occured after 36 h cultivation at 55°C and pH 7.0. Cell culture and crude enzyme of the isolates were tested on chitin of B. tabaci and the effect was observed using a microscope and sterile water was used as a negative control. Hydrolytic observation showed that crude enzyme of I.21 isolate could degrade chitin of B. tabaci exoskeleton and the activity was better than that of I.5 isolate. Conclusion: Chitinase produced by Bacillus cereus I.21 strain has potential application as biocontrol agents for B. tabaci.