Microbial reclamation of shellfish wastes for the production of chitinases

Isolation, screening, and identification of chitinase-producing bacterial strains from riverbank soils at Ambo, Western Ethiopia

Chitinases are hydrolytic enzymes that dissolve the glycosidic linkages in chitin. Chitin is a cell wall component of fungi and fund in exoskeleten of worms and arthropods. Chitinase has been applied in agriculture, as a biopesticide for the control of plant fungal infections, in medicine, and in waste management. This research aimed to isolate, screen, and identification of chitinase-producing bacteria from riverbank soils. Twenty nine chitinolytic bacteria were isolated from the river bank soil samples, from which 9 of them had strong chitinolytic properties. Chitinase production was determined by zones of hydrolysis produced after 96 h of incubation at 37 °C. The different bacterial isolates were characterized morphologically, microscopically, and biochemically and finally eight strain were identified at species level by Matrix Assisted Laser Desorption Ionization - Time of Flight Mass Spectrometry (MALDI-TOF MS). From the eight, bacterial isolates investigated in this study Stenotrophomonas maltophilia showed the highest chitinase enzyme activity (625 μg/mL) followed by Pseudomonas putida with the enzyme activity of (553 μg/mL) and the least enzyme activity was recorded for Lilliottia amnigena (80 μg/mL). An incubation temperature of 45 °C, neutral pH and an incubation period of 96 h are found to be the optimum condition for the chitinase enzyme production from Stenotrophomonas maltophilia. The results of this study indicated the possibility of the production of chitinase from the chitinolytic bacterial isolates, which was highly useful for a variety of applications, including biocontrol of harmful insects and pathogenic fungi as well as in the biochemical, pharmaceutical, and medical sectors.

Microbial decomposition of crustacean shell for production of bioactive metabolites and study of its fertilizing potential

Crustacean shell waste disposal is considered as biggest problem in seafood processing centers. Incineration and landfilling are the commonest ways of disposal of the waste which causes environmental pollution. Microbial bio-conversion is one of the promising approaches to minimize the wastes by utilizing the same for deriving different value added metabolites. In this perspective, chitinase- and protease-producing bacterial strains were isolated from shrimp culture pond, and the potent isolate was subsequently identified as Alcaligenes faecalis SK10. Fermentative optimization of the production of chitinase (85.42 U/ml), protease (58.57 U/ml), and their catalytic products, viz., N-acetylamino sugar (84 μg/ml) and free amino acids (112 μg/ml), were carried out by utilizing shrimp and crab shell powder as principal substrate. The fermented hydrolysate (FH) was subsequently applied to evaluate its potential to be a candidate fertilizer for the growth of leguminous plant Pisum sativum and Cicer arietinum, and the results were compared with chitin, chitosan, and commercial biofertilizer amended group. The results revealed that FH have paramount potential to improve plants morpho-physiological parameters like stem and root length, chlorophyll, cellular RNA, protein content, and soil physico-chemical parameters like total nitrogen, magnesium, calcium, phosphorus, and potassium significantly (p < 0.05). Moreover, the application of FH also selectively encouraged the growth of free-living nitrogen-fixing bacteria, Rhizobium, phosphate-solubilizing bacteria in the soil by 4.82- and 5.27-, 5.57- and 4.71, and 7.64- and 6.92-fold, respectively, in the rhizosphere of P. sativum and C. arietinum, which collectively is a good sign for an ideal biofertilizer. Co-supplementation of FH with commercial PGPR-biofertilizer significantly influenced the morpho-physiological attributes of plant and physico-chemical and microbial attributes of soil. The study validated proficient and sustainable utilization of fermented hydrolysate of waste crustacean shell as biofertilizer.

An Overview of Metabolic Activity, Beneficial and Pathogenic Aspects of Burkholderia Spp

Burkholderia is an important bacterial species which has different beneficial effects, such as promoting the plant growth, including rhizosphere competence for the secretion of allelochemicals, production of antibiotics, and siderophores. In addition, most of Burkholderia species have demonstrated promising biocontrol action against different phytopathogens for diverse crops. In particular, Burkholderia demonstrates significant biotechnological potential as a source of novel antibiotics and bioactive secondary metabolites. The current review is concerned with Burkholderia spp. covering the following aspects: discovering, classification, distribution, plant growth promoting effect, and antimicrobial activity of different species of Burkholderia, shedding light on the most important secondary metabolites, their pathogenic effects, and biochemical characterization of some important species of Burkholderia, such as B. cepacia, B. andropogonis, B. plantarii, B. rhizoxinica, B. glumae, B. caryophylli and B. gladioli.

Comparative bioefficacy of Bacillus and Pseudomonas chitinase against Helopeltis theivora in tea (Camellia sinensis (L.) O.Kuntze

Tea (Camellia sinensis (L.) O.Kuntze) is an industry-oriented economical crop in India. Among the sap sucking pests, tea mosquito bug (Helopeltis theivora) is one of the most serious pests causing heavy crop loss in tea plantation. Continuous use of chemical pesticides causes environmental pollution and health hazards besides developing pesticide residues in tea powder. The control of pests by bacterial metabolite is an alternative that may contribute to reduce or eliminate the chemical pesticide use. The use of chitinase as a biological control is an emerging field of research. In the present study, Chitinase (~ 25 kDa) was purified from Bacillus cereus C-13 strain using gel-filtration chromatography and further characterized for its optimum pH, temperature and substrate specificity. Bioefficacy of chitinase from B. cereus C-13 was compared with our previously reported Pseudomonas fluorescens MP-13 chitinase against H. theivora. Result concluded that, 100% and 78% mortality was observed by using P. fluorescens MP-13 chitinase and B. cereus C-13 chitinase, respectively. In future, bacterial chitinase can be utilized in eco-friendly pest management strategies.

Comparative biocontrol ability of chitinases from bacteria and recombinant chitinases from the thermophilic fungus Thermomyces lanuginosus

Microbial chitinases (EC 3.2.1.14) are known to hydrolyse the chitinous gut epithelium of insects and cell walls of many fungi. In this study, seven chitinases from different bacteria and fungi were produced, characterized and their biocontrol abilities against graminaceous stem borers Eldana saccharina, Chilo partellus and Sesamia calamistis were assessed. All chitinases were stable over broad ranges of pH and temperature, however, recombinant fungal chitinases were more acid-stable than the bacterial counterparts. Chitinases from the thermophilic filamentous fungi Thermomyces lanuginosus SSBP (Chit1) and from Bacillus licheniformis (Chit lic) caused 70% and 80% mortality, respectively, in second instar larvae of E. saccharina. Six of the seven partially-purified microbial chitinases inhibited Aspergillus niger, A. flavus, A. alliaceus, A. ochraceus, Fusarium verticillioides and Mucor sp. Overall, microbial chitinases show promise as biocontrol agents of fungi and stalk-boring lepidopterans.

Chitinases: An update

Chitin, the second most abundant polysaccharide in nature after cellulose, is found in the exoskeleton of insects, fungi, yeast, and algae, and in the internal structures of other vertebrates. Chitinases are enzymes that degrade chitin. Chitinases contribute to the generation of carbon and nitrogen in the ecosystem. Chitin and chitinolytic enzymes are gaining importance for their biotechnological applications, especially the chitinases exploited in agriculture fields to control pathogens. Chitinases have a use in human health care, especially in human diseases like asthma. Chitinases have wide-ranging applications including the preparation of pharmaceutically important chitooligosaccharides and N-acetyl D glucosamine, preparation of single-cell protein, isolation of protoplasts from fungi and yeast, control of pathogenic fungi, treatment of chitinous waste, mosquito control and morphogenesis, etc. In this review, the various types of chitinases and the chitinases found in different organisms such as bacteria, plants, fungi, and mammals are discussed.

Isolation and characterization of chitosan-producing bacteria from beaches of chennai, India

Chitosan is a deacetylated product of chitin produced by chitin deacetylase, an enzyme that hydrolyses acetamido groups of N-acetylglucosamine in chitin. Chitosan is a natural polymer that has great potential in biotechnology and in the biomedical and pharmaceutical industries. Commercially, it is produced from chitin via a harsh thermochemical process that shares most of the disadvantages of a multistep chemical procedure. It is environmentally unsafe and not easily controlled, leading to a broad and heterogeneous range of products. An alternative or complementary procedure exploiting the enzymatic deacetylation of chitin could potentially be employed, especially when a controlled and well-defined process is required. In this study, 20 strains of bacteria were isolated from soil samples collected from different beaches of Chennai, India. Of these 20 bacterial strains, only 2 strains (S3, S14) are potent degrader of chitin and they are also a good producer of the enzyme chitin deacetylase so as to release chitosan.

Biodegradation of shrimp processing bio-waste and concomitant production of chitinase enzyme and N-acetyl-D-glucosamine by marine bacteria: production and process optimization

A total of 250 chitinolytic bacteria from 68 different marine samples were screened employing enrichment method that utilized native chitin as the sole carbon source. After thorough screening, five bacteria were selected as potential cultures and identified as; Stenotrophomonas sp. (CFR221 M), Vibrio sp. (CFR173 M), Phyllobacteriaceae sp. (CFR16 M), Bacillus badius (CFR198 M) and Bacillus sp. (CFR188 M). All five strains produced extracellular chitinase and GlcNAc in SSF using shrimp bio-waste. Scanning electron microscopy confirmed the ability of these marine bacteria to adsorb onto solid shrimp bio-waste and to degrade chitin microfibers. HPLC analysis of the SSF extract also confirmed presence of 36-65 % GlcNAc as a product of the degradation. The concomitant production of chitinase and GlcNAc by all five strains under SSF using shrimp bio-waste as the solid substrate was optimized by 'one factor at a time' approach. Among the strains, Vibrio sp. CFR173 M produced significantly higher yields of chitinase (4.8 U/g initial dry substrate) and GlcNAc (4.7 μmol/g initial dry substrate) as compared to other cultures tested. A statistically designed experiment was applied to evaluate the interaction of variables in the biodegradation of shrimp bio-waste and concomitant production of chitinase and GlcNAc by Vibrio sp. CFR173 M. Statistical optimization resulted in a twofold increase of chitinase, and a 9.1 fold increase of GlcNAc production. These results indicated the potential of chitinolytic marine bacteria for the reclamation of shrimp bio-waste, as well as the potential for economic production of chitinase and GlcNAc employing SSF using shrimp bio-waste as an ideal substrate.

Chitinase production by Bacillus thuringiensis and Bacillus licheniformis: their potential in antifungal biocontrol

Thirty bacterial strains were isolated from the rhizosphere of plants collected from Egypt and screened for production of chitinase enzymes. Bacillus thuringiensis NM101-19 and Bacillus licheniformis NM120-17 had the highest chitinolytic activities amongst those investigated. The production of chitinase by B. thuringiensis and B. licheniformis was optimized using colloidal chitin medium amended with 1.5% colloidal chitin, with casein as a nitrogen source, at 30°C after five days of incubation. An enhancement of chitinase production by the two species was observed by addition of sugar substances and dried fungal mats to the colloidal chitin media. The optimal conditions for chitinase activity by B. thuringiensis and B. licheniformis were at 40°C, pH 7.0 and pH 8.0, respectively. Na(+), Mg(2+), Cu(2+), and Ca(2+) caused enhancement of enzyme activities whereas they were markedly inhibited by Zn(2+), Hg(2+), and Ag(+). In vitro, B. thuringiensis and B. licheniformis chitinases had potential for cell wall lysis of many phytopathogenic fungi tested. The addition of B. thuringiensis chitinase was more effective than that of B. licheniformis in increasing the germination of soybean seeds infected with various phytopathogenic fungi.

Characterization of a chitinase with antifungal activity from a native Serratia marcescens B4A

Chitinases have the ability of chitin digestion that constitutes a main compound of the cell wall in many of the phytopathogens such as fungi. In the following investigation, a novel chitinase with antifungal activity was characterized from a native Serratia marcescens B4A. Partially purified enzyme had an apparent molecular mass of 54 kDa. It indicated an optimum activity in pH 5 at 45°C. Enzyme was stable in 55°C for 20 min and at a pH range of 3-9 for 90 min at 25°C. When the temperature was raised to 60°C, it might affect the structure of enzymes lead to reduction of chitinase activity. Moreover, the Km and Vmax values for chitin were 8.3 mg/ml and 2.4 mmol/min, respectively. Additionally, the effect of some cations and chemical compounds were found to stimulate the chitinase activity. In addition, Iodoacetamide and Idoacetic acid did not inhibit enzyme activity, indicating that cysteine residues are not part of the catalytic site of chitinase. Finally, chitinase activity was further monitored by scanning electronic microscopy data in which progressive changes in chitin porosity appeared upon treatment with chitinase. This enzyme exhibited antifungal activity against Rhizoctonia solani, Bipolaris sp, Alternaria raphani, Alternaria brassicicola, revealing a potential application for the industry with potentially exploitable significance. Fungal chitin shows some special features, in particular with respect to chemical structure. Difference in chitinolytic ability must result from the subsite structure in the enzyme binding cleft. This implies that why the enzyme didn't have significant antifungal activity against other Fungi.

ICChI, a glycosylated chitinase from the latex of Ipomoea carnea

A multi-functional enzyme ICChI with chitinase/lysozyme/exochitinase activity from the latex of Ipomoea carnea subsp. fistulosa was purified to homogeneity using ammonium sulphate precipitation, hydrophobic interaction and size exclusion chromatography. The enzyme is glycosylated (14-15%), has a molecular mass of 34.94 kDa (MALDI-TOF) and an isoelectric point of pH 5.3. The enzyme is stable in pH range 5.0-9.0, 80 degrees C and the optimal activity is observed at pH 6.0 and 60 degrees C. Using p-nitrophenyl-N-acetyl-beta-D-glucosaminide, the kinetic parameters K(m), V(max), K(cat) and specificity constant of the enzyme were calculated as 0.5mM, 2.5 x 10(-8)mol min(-1)microg enzyme(-1), 29.0 s(-1) and 58.0mM(-1)s(-1) respectively. The extinction coefficient was estimated as 20.56 M(-1)cm(-1). The protein contains eight tryptophan, 20 tyrosine and six cysteine residues forming three disulfide bridges. The polyclonal antibodies raised and immunodiffusion suggests that the antigenic determinants of ICChI are unique. The first fifteen N-terminal residues G-E-I-A-I-Y-W-G-Q-N-G-G-E-G-S exhibited considerable similarity to other known chitinases. Owing to these unique properties the reported enzyme would find applications in agricultural, pharmaceutical, biomedical and biotechnological fields.

Culture of Staphylococcus xylosus in fish processing by-product-based media for lipase production

AIMS

The objective of this study was to demonstrate that fish-processing by-products could be used as sole raw material to sustain the growth of Staphylococcus xylosus for lipase production.

METHODS AND RESULTS

Bacterial growth was tested on supernatants generated by boiling (100 degrees C for 20 min) of tuna, sardine, cuttlefish and shrimp by-products from fish processing industries. Among all samples tested, only supernatants generated from shrimp and cuttlefish by-products sustained the growth of S. xylosus. Shrimp-based medium gave the highest growth (A(600) = 22) after 22 h of culture and exhibited the maximum lipase activity (28 U ml(-1)). This effect may be explained by better availability of nutrients, especially, in shrimp by-products. Standard medium (SM) amendments to sardine and tuna by-product-based media stimulated the growth of S. xylosus and the highest A(600) values were obtained with 75% SM. Lipase activity, however, remained below 4 U ml(-1) for both sardine and tuna by-product-based media.

CONCLUSIONS

Fish by-products could be used for the production of highly valuable enzymes.

SIGNIFICANCE AND IMPACT OF THE STUDY

The use of fish by-products in producing S. xylosus-growth media can reduce environmental problems associated with waste disposal and, simultaneously, lower the cost of biomass and enzyme production.

Occurrence and activity of microorganisms in shrimp waste

This study aimed to determine the occurrence and respiration activity of heterotrophic bacteria and fungi in shrimp shell waste and to evaluate the role of chitinolytic bacteria and fungi in its decomposition. The highest levels of bacteria were found in shrimp heads sections and the lowest in exoskeletons. The level of fungi was much lower, with the highest proportion present in heads sections and the lowest in exoskeletons. Chitinolytic bacteria constituted a small percentage of the total heterotrophic bacteria in fresh shrimp waste, averaging 4% in exoskeletons, 2.4% in all parts, and 2% in heads. No chitinolytic bacteria were detected in stored waste. In contrast, the percentage of chitinolytic fungi in shrimp waste was much higher than that of bacteria. Chitinolytic fungi constituted 25-60% of the total fungi in fresh waste and 15-40% in stored waste. Chitinolytic bacteria isolated from heads sections were characterized by the highest chitinolytic activity, averaging 11.2 nmol of methylumbelliferyl x mg(-1) protein x h(-1), whereas the lowest activity was in strains from exoskeletons, averaging 3.2 nmol of methylumbelliferyl x mg(-1) protein x h(-1). The chitinolytic activity of fungi isolated from all parts waste, head sections, and exoskeletons was similar. The respiration activity of microorganisms in fresh and stored waste was similar. Oxygen consumption activity increased during incubation and approached a saturation value between days 4 and 5. No correlation between the end value of respiratory activity in the analyzed section of shrimp discard after 5 days and the level of bacteria and fungi was observed. The only significant correlation observed was between the respiratory activity of the shrimp and the level of fungi. The respiration activity significantly depended on the analyzed section of shrimp discard (p<0.000).

Bacillus pumilusSG2 isolated from saline conditions produces and secretes two chitinases

AIMS

Isolation and characterization of chitinases from a halotolerant Bacillus pumilus.

METHODS AND RESULTS

Bacillus pumilus strain SG2 was isolated from saline conditions. It is able to produce chitinase activity at high salt concentration. SDS-PAGE analysis of the B. pumilus SG2 culture supernatant showed two major bands that were induced by chitin. The amino acid sequence of the two proteins, designated ChiS and ChiL, showed a high homology with the chitinase of B. subtilis CHU26, and chitinase A of B. licheniformis, respectively. N-terminal signal peptide of both proteins was also determined. The molecular weight and isoelectric point of the chitinases were determined to be 63 and 74 kDa, and 4.5 and 5.1, for ChiS and ChiL respectively. The genes encoding for both chitinases were isolated and their sequence determined. The regulation of the chitinase genes is under the control of the catabolite repression system.

CONCLUSIONS

Secreted chitinase genes and their flanking region on the genome of B. pumilus SG2 have been identified and sequenced.

SIGNIFICANCE AND IMPACT OF THE STUDY

This is the first report of a multiple chitinases-producing B. pumilus halotolerant strain. We have identified two chitinases by using a reverse genetics approach. The chitinases show resistance to salt.

Purification of Aspergillus sp. S1-13 chitinases and their role in saccharification of chitin in mash of solid-state culture with shellfish waste

In a suspension of solid-state culture of Aspergillus sp. S1-13 containing a lactic acid-treated crab shell as the substrate, the saccharification of chitin in the shell proceeded to form N-acetylglucosamine (GlcNAc): the culture was the source of chitin and chitinases. The analysis of chitinases in the water-extract of the solid-state culture indicated occurrence of an exochitinase (Exo, MW 73 kDa) and two endochitinases. The amounts of the endochitinases suggested that one of them (Endo-1, MW 45 kDa) might be the main species in the chitin-saccharification. The amount of GlcNAc released from the LA-treated crab shell by the combined action of isolated Exo and Endo-1 was very small, predicting participation in the saccharification of other enzyme species, which might be hardly extracted with water from the solid-state culture. The re-extraction of the solid-state culture using 2 M KCl, which was extracted with water beforehand, demonstrated another endochitinase (Endo-2, MW 51 kDa). Endo-2 isolated from the salt-extract can adsorb to chitin, and can hydrolyze the chitin in the adsorbed state. The roles of these chitinases in the chitin-saccharification based on their properties and combined action were discussed.

Directed evolution for increased chitinase activity

Directed evolution through DNA shuffling and screening was used to enhance the catalytic ability of a fungal, Beauveria bassiana, chitinase, Bbchit1. The Bbchit gene was first linked to various prokaryotic signal sequences and expressed in Escherichia coli. The signal peptide, PelB, from Erwinia carotovora resulted in greatest chitinase secretion into broth. The nucleotide sequence expressing PelB signal peptide was then incorporated into an E. coli vector to express Bbchit1 variants generated by three rounds of DNA shuffling. A Bbchit1 library with 150,000 variants was constructed with a nucleotide point mutation frequency of 0.6% and screened for chitinolytic activity. Two Bbchit1 variants (SHU-1 and SHU-2) were selected that showed increased chitinolytic activity compared to the wild type. Sequence analysis of these variants revealed mutations in amino acid residues that would not normally be considered for rational design of improved chitinase activity. The amino acid substitutions occurred outside of the two putative substrate-binding sites and the catalytic region.

Antifungal activity and enhancement of plant growth by Bacillus cereus grown on shellfish chitin wastes

Bacillus cereus QQ308 produced antifungal hydrolytic enzymes, comprising chitinase, chitosanase and protease, when grown in a medium containing shrimp and crab shell powder (SCSP) produced from marine waste. The growth of the plant-pathogenic fungi Fusarium oxysporum, Fusarium solani, and Pythium ultimum were considerably affected by the presence of the QQ308 culture supernatant. The supernatant inhibited spore germination and germ tube elongation of F. oxysporum, F. solani, and P. ultimum. The increase in the growth time of the fungal culture was associated with a gradual decrease in inhibition. Besides antifungal activity, QQ308 enhanced growth of Chinese cabbage. These characteristics were unique among known strains of B. cereus. To our knowledge, this is the first report on the antifungal and Chinese cabbage growth enhancing compounds produced by B. cereus.

Cloning, expression, and characterization of a highly thermostable family 18 chitinase from Rhodothermus marinus

A family 18 chitinase gene chiA from the thermophile Rhodothermus marinus was cloned and expressed in Escherichia coli. The gene consisted of an open reading frame of 1,131 nucleotides encoding a protein of 377 amino acids with a calculated molecular weight of 42,341 Da. The deduced ChiA was a non-modular enzyme with one unique glycoside hydrolase family 18 catalytic domain. The catalytic domain exhibited 43% amino acid identity with Bacillus circulans chitinase C. Due to poor expression of ChiA, a signal peptide-lacking mutant, chiADeltasp, was designed and used subsequently. The optimal temperature and pH for chitinase activity of both ChiA and ChiADeltasp were 70 degrees C and 4.5-5, respectively. The enzyme maintained 100% activity after 16 h incubation at 70 degrees C, with half-lives of 3 h at 90 degrees C and 45 min at 95 degrees C. Results of activity measurements with chromogenic substrates, thin-layer chromatography, and viscosity measurements demonstrated that the chitinase is an endoacting enzyme releasing chitobiose as a major end product, although it acted as an exochitobiohydrolase with chitin oligomers shorter than five residues. The enzyme was fully inhibited by 5 mM HgCl2, but excess ethylenediamine tetraacetic acid relieved completely the inhibition. The enzyme hydrolyzed 73% deacetylated chitosan, offering an attractive alternative for enzymatic production of chitooligosaccharides at high temperature and low pH. Our results show that the R. marinus chitinase is the most thermostable family 18 chitinase isolated from Bacteria so far.

Purification and characterization of an endochitinase produced by Colletotrichum gloeosporioides

The phytopathogenic fungus Colletotrichum gloeosporioides was analyzed for chitinase activity, the best production occurring at the fourth day. A 43 kDa endochitinase with specific activity of 413 U microg(-1) protein was purified corresponding to a 75% yield. The optima of temperature and pH for the enzyme were 50 degrees C and pH 7.0, respectively. The enzyme showed a high stability at 50 degrees C and pH 7.0. Values of pH from 5.0 up to 7.0 gave, at least, 50% of maximum activity, suggesting a biotechnological application. Further studies are in progress to determine the possible use of this endochitinase in biological control.

Saccharification of chitin using solid-state culture of Aspergillus sp. S1-13 with shellfish waste as a substrate

Saccharification of chitin was performed in a suspension (mash) of a solid-state culture of chitinase-producing Aspergillus sp. Sl-13 with acid-treated shellfish waste as a substrate. The conditions for the saccharifying reaction and the solid-state cultivation were examined from the viewpoint of saccharification in the mash. Optimum cultivation conditions were defined: a solid-state medium consisting of 5 g of 10% lactic acid-treated crab shells (0.50-2.36 mm in size) and 3 ml of a basal medium (0.028% KH2PO4 0.007% CaCl2.2H2O, and 0.025% MgSO4.7H2O) supplemented with 0.3% peptone was inoculated with 4 ml of spore suspension (1 x 10(7) spores/ml), and the water content of the medium was adjusted to 75%; static cultivation at 37 degrees C for 7 d. When a culture obtained under the optimum conditions was suspended in 70 ml of 50 mM sodium phosphate-citrate buffer (pH 4.0) and incubated at 45 degrees C for 11-13 d, 55 mM N-acetylglucosamine (GlcNAc) was formed in the solid-state culture mash, indicating that at least 33% of the initial chitin in the solid material was hydrolyzed. Through the experiments, the amounts of G1cNAc formed in the solid-state culture mash varied in a way similar to that of the water-extractable pnitrophenyl beta-D-N-acetylglucosaminide-hydrolyzing enzyme in the culture, but not to that of the colloidal chitin-hydrolyzing enzyme. G1cNAc-assimilating lactic acid bacteria, which were inoculated into the mash after or at the start of the saccharification, formed lactic acid with decreasing GlcNAc.

Utilization of shrimp shellfish waste as a substrate for solid-state cultivation of Aspergillus sp. S1-13: Evaluation of a culture based on chitinase formation which is necessary for chitin-assimilation

The utilization of shrimp shellfish waste as a substrate for solid-state cultivation of a filamentous fungus, Aspergillus sp. S1-13, was investigated. The organism was selected from among 220 isolates based on the productivity of its chitinolytic enzyme (chitinase), which might reflect microbial growth. The enzyme was produced only when the organism was grown on medium containing the shellfish waste. The addition of 58-65% water (w/w) to the medium was effective in enhancing production, and a certain amount of enzyme was observed in media of higher water content (up to about 75%). The initial pH and nitrogen source (ammonium sulfate) of the solid-state medium also affected the amount of enzyme. The amount of enzyme increased 2-fold in an optimum solid-state medium: 5 g of shrimp shellfish waste and 3 ml of basal medium (pH 5) containing 0.1% (NH4)2SO4 was inoculated with 4 ml of spore suspension; static cultivation at room temperature. The amount increased further (1.5-fold) when the cultivation was carried out at 37 degrees C, with 1.85 units of the enzyme formed from 1 g of shrimp shellfish waste. An analysis by ion-exchange column chromatography suggested the presence of at least two colloidal chitin-hydrolyzing enzymes and one p-nitrophenyl beta-D-N-acetylglucosaminide-hydrolyzing enzyme in an extract of the solid-state culture. The elution profile was similar to that obtained with a liquid culture filtrate.