Optimization of Bioprocess Variables for Fungal Lipase Production using Statistical Experimental Design: A Mini Review

Lipases hold the important role in wide spectrum of biotechnological applications. Lipases are unique, not only due to their ability to perform hydrolysis of fats into fatty acids and glycerol at the water-lipid interface, but also can reverse the reaction in non-aqueous media. Currently, the studies revealed that fungi are the one of choice for lipase production. Some important lipase-producing fungal genera include Aspergillus, Penicillium, Rhizopus, Candida, Geotrichum, etc. The development of response surface methodology applied to optimize fungal lipase production is discussed.

Variation of mucin adhesion, cell surface characteristics, and molecular mechanisms among Lactobacillus plantarum isolated from different habitats

The adhesion ability to mucin varied greatly among 18 Lactobacillus plantarum isolates depending on their isolation habitats. Such ability remained at high level even though they were sequentially exposed to the gastrointestinal (GI) stresses. The majority of L. plantarum isolated from shrimp intestine and about half of food isolates exhibited adhesion ability (51.06-55.04%) about the same as the well-known adhesive L. plantarum 299v. Interestingly, five infant isolates of CIF17A2, CIF17A4, CIF17A5, CIF17AN2, and CIF17AN8 exhibited extremely high adhesion ranging from 62.69 to 72.06%. Such highly adhesive property correlating to distinctively high cell surface hydrophobicity was significantly weaken after pretreatment with LiCl and guanidine-HCl confirming the entailment of protein moiety. Regarding the draft genome information, all molecular structures of major cell wall-anchored proteins involved in the adhesion based on L. plantarum WCSF1, including lp_0964, lp_1643, lp_3114, lp_2486, lp_3127, and lp_3059 orthologues were detected in all isolates. Exceptionally, the gene-trait matching between yeast agglutination assay and the relevant mannose-specific adhesin (lp_1229) encoding gene confirmed the Msa absence in five infant isolates expressed distinctively high adhesion. Interestingly, the predicted flagellin encoding genes (fliC) firstly revealed in lp_1643, lp_2486, and lp_3114 orthologues may potentially contribute to such highly adhesive property of these isolates.Peer reviewe

Hyperthermostable cellulolytic and hemicellulolytic enzymes and their biotechnological applications

Hyperthermal cellulases and hemicellulases have been intensively studied due to their highly potential applications at extreme temperatures, which mimic industrial processes involving cellulose and hemicellulose degradation. More than 50 species of hyperthermophiles have been isolated, many of which possess hyperthermal enzymes required for hydrolyzing cellulose and hemicelluloses. Endoglucanases, exoglucanases, cellobiohydrolases, xylanases, β-glucosidase and β-galactosidase, which are produced by the hyperthermophiles, are resistant to boiling temperature. The characteristics of these enzymes and the ability to maintain their functional integrity at high temperature as well as their biotechnological application are discussed

Effect of deacetylation conditions on antimicrobial activity of chitosans prepared from carapace of black tiger shrimp (Penaeus monodon)

Chitosan was prepared from black tiger shrimp carapace by deacetylation process performed in 50% NaOH at 100oC under vacuum, nitrogen and regular atmospheres. Each condition was maintained for 0.5, 1.0 and 2.0 h. Chitosan obtained from 1.0 h of deacetylation under regular atmosphere showed the lowest minimum inhibitory concentration (MIC) value of 625 ppm against Escherichia coli and Staphylococcus aureus, while Candida albicans was inhibited at MIC value of 312.5 ppm due to its higher degree of deacetylation (% DD) and lower molecular weight (MW) compared to chitosan deacetylated under vacuum and nitrogen atmospheres. Chitosan hydrolysates obtained from both chemical (H2O2 in the presence of ferricions) and enzymatic (lysozyme) hydrolysis were not as inhibitory as the native one, except that from chemical hydrolysis, which showed the elevation of the antifungal activity against C. albicans when longer hydrolysis was performed. However, antibacterial activity against E. coli decreased when the MW of hydrolyzed chitosan decreased

Effect of culture medium on polymer production and temperature on recovery of polymer produced from newly identified Rhyzopus oryzae ST29

Thermotolerant fungal isolate ST29 was identified by observing on cell morphology and molecular technique based on internal transcribed spacer (ITS) gene to be Rhizopus oryzae. Among four culture media tested, the strain exhibited the highest growth in yeast malt extract (YM) medium (4.87 g/l), followed by Sabouraud dextrose broth (SDB) (4.25 g/l), potato dextrose broth (PDB) (4.10 g/l) and palm oil mill effluent (POME) (3.29 g/l), respectively, after 4 days cultivation at 45oC. However, the strain was found to produce polymer only in POME medium at 45oC, but not in the three synthetic media tested. Effect of temperature on separation of the biopolymer produced by this fungal strain was studied by incubating the culture broth in water bath with temperatures in the range of room temperature to 70oC. The biopolymer was recovered by filtration, centrifugation, and precipitation by adding 4 volumes of 95% ethanol, then freeze-drying. These temperatures therefore had no influence on the biopolymer yields (5.58-5.78 g/l) or on biomass yields (2.90-3.29 g/l)

Screening of lactic acid bacteria from gastrointestinal tracts of marine fish for their potential use as probiotics

One hundred and sixty isolates of lactic acid bacteria (LAB) with inhibitory activity against pathogenic Escherichia coli were isolated from gastrointestinal tracts of fish, shrimp and shellfish. One hundred and sixteen isolates were obtained from fish, twenty isolates from shrimp and twenty-four isolates from shellfish. Three strains were selected based on their bile and acid tolerances. All acid-tolerant strains showed inhibitory activity against human pathogens, including Staphylococcus aureus, Listeria monocytogenes, Salmonella sp. and Escherichia coli. However, the antibacterial activities were lost when the culture supernatants were neutralized to pH 6.5- 7.0 and treated with catalase, indicating that the inhibition may be contributed by acid and hydrogen-peroxide production of the strains. Nucleotide sequences of their 16s rDNA showed 98% (655/668 bp), 97% (691/712 bp) and 98% (492/501 bp) homology to Pediococcus pentosaceus LM2, Pediococcus pentosaceus SL4 and Enterococcus faecium SF, respectively

Antimicrobial activities of essential oils and crude extracts from tropical Citrus spp. against food-related microorganisms

Ethyl acetate extracts and hydrodistillated-essential oils from peels of Citrus spp. were investigated for their antimicrobial activities against food related microorganisms by broth microdilution assay. Overall, ethyl acetate extracts from all citrus peels showed stronger antimicrobial activities than their essential oils obtained from hydrodistillation. The ethyl acetate extract of kaffir lime (Citrus hystrix DC.) peel showed broad spectrum of inhibition against all Gram-positive bacteria, yeast and molds including Staphylococcus aureus, Bacillus cereus, Listeria monocytogenes, Saccharomyces cerevisiae var. sake and Aspergillus fumigatus TISTR 3180. It exhibited minimum inhibitory concentration (MIC) values of 0.28 and 0.56 mg/ml against Sac. cerevisiae var. sake and B. cereus, respectively while the minimum bactericidal concentration (MBC) values against both microbes were 0.56 mg/ml. The MIC values of the extract against L. monocytogenes, A. fumigatus TISTR 3180 and S. aureus were 1.13 mg/ml while the MBC values against L. monocytogenes as well as A. fumigatus TISTR 3180 and S. aureus were 2.25 and 1.13 mg/ml, respectively. The major components of the ethyl acetate extract from kaffir lime were limonene (31.64 %), citronellal (25.96 %) and b-pinene (6.83 %) whereas b-pinene (30.48 %), sabinene (22.75 %) and citronellal (15.66 %) appeared to be major compounds of the essential oil obtained from hydrodistillation

Isolation and screening of D-amino acid amidase producing bacteria from soil samples

Isolation and screening of D-amino acid amidase producing bacteria from fifty-four soil samples taken on Hat Yai campus of Prince of Songkla University were conducted using acclimation culture technique in medium broth containing D-phenylalanine amide as a sole source of nitrogen. Bacteria capable of growing at 30ºC and 45ºC were screened and isolated. Twenty-one and seventeen soil samples showed the hydrolysis of D-phenylalanine amide to D-phenylalanine determined by thin layer chromatography and forty-seven and thirty-four strains were isolated at 30ºC and 45ºC, respectively. Each isolate obtained was screened for its ability to degrade D-phenylalanine amide. Thirteen of forty-seven strains and nineteen of thirty-four strains isolated at 30ºC and 45ºC, respectively exhibited D-phenylalanine amide degradation. However, only isolate BS16 exhibited degradation toward D-tert-leucine.The enzyme activity toward D-phenylalanine amide was detected from the bacterial cells, but not in supernatant indicating that the amidase was an intracellular enzyme. The bacterial cells grown in the broth with and without D-amino acid amide showed enzyme activity leading to the conclusion that it was constitutive enzyme

Combined effect of crude herbal extracts, pH and sucrose on the survival of Candida parapsilosis and Zygosaccharomyces fermentati in orange juice

The purpose of this study was to evaluate the antimicrobial activity of crude extracts of cinnamon and clove compared with potassium sorbate against food spoilage yeasts isolated from orange juice (Candidaparapsilosis and Zygosaccharomyces fermentati). The ethanolic extract of both cinnamon and clove showed activity against C. parapsilosis and Z. fermentati with minimum inhibitory concentrations (MIC) of 1.0 and0.5 mg/ml by agar dilution method, respectively. While potassium sorbate showed activity against both yeasts with MIC 0.4 mg/ml. The combined effect of pH, concentration of sucrose and cinnamon extract or cloveextract or potassium sorbate in orange juice on the survival of the isolated yeasts were studied using Response Surface Methodology. The pH of orange juice and the concentration of cinnamon or clove extracthad the most significant (P<0.05) effect on the survival of C. parapsilosis and Z. fermentati while concentration of sucrose had the least effect. Survival of C. parapsilosis and Z. fermentati was mostly affected by theconcentration of potassium sorbate but pH and the concentration of sucrose did not have significant effect on the survival of Z. fermentati

Variation of mucin adhesion, cell surface characteristics, and molecular mechanisms among Lactobacillus plantarum isolated from different habitats

The adhesion ability to mucin varied greatly among 18 Lactobacillus plantarum isolates depending on their isolation habitats. Such ability remained at high level even though they were sequentially exposed to the gastrointestinal (GI) stresses. The majority of L. plantarum isolated from shrimp intestine and about half of food isolates exhibited adhesion ability (51.06–55.04%) about the same as the well-known adhesive L. plantarum 299v. Interestingly, five infant isolates of CIF17A2, CIF17A4, CIF17A5, CIF17AN2, and CIF17AN8 exhibited extremely high adhesion ranging from 62.69 to 72.06%. Such highly adhesive property correlating to distinctively high cell surface hydrophobicity was significantly weaken after pretreatment with LiCl and guanidine-HCl confirming the entailment of protein moiety. Regarding the draft genome information, all molecular structures of major cell wall-anchored proteins involved in the adhesion based on L. plantarum WCSF1, including lp_0964, lp_1643, lp_3114, lp_2486, lp_3127, and lp_3059 orthologues were detected in all isolates. Exceptionally, the gene-trait matching between yeast agglutination assay and the relevant mannose-specific adhesin (lp_1229) encoding gene confirmed the Msa absence in five infant isolates expressed distinctively high adhesion. Interestingly, the predicted flagellin encoding genes (fliC) firstly revealed in lp_1643, lp_2486, and lp_3114 orthologues may potentially contribute to such highly adhesive property of these isolates.</p