Antibacterial and antifungal activity of methanolic extracts of Salix alba L. against various disease causing pathogens / Atividade antibacteriana e antifúngica de extratos metanólicos de Salix alba L. contra vários patógenos que causam doenças

Abstract The present study was aimed to manifest the antibacterial and antifungal activity of methanolic extracts of Salix alba L. against seven Gram-positive and Gram-negative bacterial pathogens e.g. Streptococcus pyogenes, Staphylococcus aureus (1), S. aureus (2), Shigella sonnei, Escherichia coli (1), E. coli (2) and Neisseria gonorrhoeae and three fungal isolates from the air such as Aspergillus terreus, A. ornatus, and Rhizopus stolonifer. Two different serotypes of S. aureus and E. coli were used. The agar well-diffusion method results showed the dose-dependent response of plant extracts against bacterial and fungal strains while some organisms were found resistant e.g. E. coli (1), S. sonnei, A. terreus and R. stolonifer. The highest antibacterial activity was recorded at 17.000±1.732 mm from 100 mg/mL of leaves methanolic extracts against S. pyogenes while the activity of most of the pathogens decreased after 24 h of incubation. The highest antifungal activity was reported at 11.833±1.0 mm against A. ornatus at 50 mg/mL after 48 h of the incubation period. These experimental findings endorse the use of S. alba in ethnopharmacological formulations and suggest the use of methanolic extracts of the said plant to develop drugs to control the proliferation of resistant disease causing pathogenic microbes.

Resumo O presente estudo teve como objetivo manifestar a atividade antibacteriana e antifúngica de extratos metanólicos de Salix alba L. contra sete patógenos bacterianos Gram-positivos e Gram-negativos. Streptococcus pyogenes, Staphylococcus aureus (1), S. aureus (2), Shigella sonnei, Escherichia coli (1), E. coli (2) e Neisseria gonorrhoeae e três isolados de fungos do ar, como Aspergillus terreus, A. ornatus, e Rhizopus stolonifer. Dois sorotipos diferentes de S. aureus e E. coli foram usados. Os resultados do método de difusão em ágar mostraram a resposta dependente da dose de extratos de plantas contra cepas de bactérias e fungos, enquanto alguns organismos foram considerados resistentes, e.g. E. coli (1), S. sonnei, A. terreus e R. stolonifer. A maior atividade antibacteriana foi registrada em 17.000 ± 1.732 de 100 mg/mL de extratos metanólicos de folhas contra S. pyogenes, enquanto a atividade da maioria dos patógenos diminuiu após 24 h de incubação. A maior atividade antifúngica foi relatada em 11,833 ± 1,0 contra A. ornatus a 50 mg/mL após 48 h do período de incubação. Esses achados experimentais endossam o uso de S. alba em formulações etnofarmacológicas e sugerem o uso de extratos metanólicos da referida planta para o desenvolvimento de fármacos que controlem a proliferação de doenças resistentes que causam micróbios patogênicos.

Higienización y eliminación fúngica en instalaciones industriales para la disminución de riesgos ocupacionales / Sanitization and fungal elimination in industrial facilities to reduce occupational risks

Se ha comprobado que la exposición a bioaerosoles se asocia con varios efectos sobre la salud, como enfermedades pulmonares y alergias. El presente estudio transversal tuvo como objetivo investigar la contaminación por hongos en varias superficies pertenecientes a dos industrias de alimentos. La toma de muestra se realizó en tres semanas, inmediatamente después de realizada la limpieza y desinfección y antes de iniciar la producción. Se recolectaron 400 muestras de superficie (vidrio, acero inoxidable, aluminio, goma y plástico), también se evaluó la eficacia del programa de higienización en el control de la población de hongos. Todas las muestras presentaron recuentos fúngicos <10 ufc/cm2, sin haber diferencias significativas entre los tipos de superficie, sin embargo, las superficies plásticas exhibieron mayor crecimiento logarítmico de los hongos. Se determinó que 49,60% de las especies identificadas correspondieron al género Penicillium. Aunque los niveles de hongos en las industrias estudiadas fueron inferiores a los niveles recomendados por la Organización Mundial de la Salud, algunas medidas de salud ambiental como lavar y desinfectar las superficies después de cada turno de trabajo, y se recomiendan inspecciones periódicas para garantizar la seguridad de los trabajadores y de los productos que allí se manufacturan(AU)

It has been proven that exposure to bioaerosols is associated with several health effects, such as pulmonary diseases and allergies. The present crosssectional study aimed to investigate fungal contamination on various surfaces belonging to two food industries. The sampling was carried out in three weeks, immediately after cleaning and disinfection and before starting production. 400 surface samples were collected (glass, stainless steel, aluminum, rubber and plastic), the effectiveness of the sanitation program in controlling the fungal population was also evaluated. All the samples presented fungal counts <10 cfu / cm2, with no significant differences between the types of surfaces, however, the plastic surfaces exhibited higher logarithmic growth of the fungi. It was determined that 49.60% of the identified species corresponded to the Penicillium genus.Although the levels of fungi in the studied baths were lower than the levels recommended by the World Health Organization, some environmental health measure ssuch as washing and disinfecting surfaces after each working shift and periodic inspections are recommended ensuring the safety of the workers and the products that are manufactured there(AU)

Conversion of renewable substrates for biosurfactant production by Rhizopus arrhizus UCP 1607 and enhancing the removal of diesel oil from marine soil

BACKGROUND: The use of agro-industrial wastes to produce high value-added biomolecules such as biosurfactants is a promising approach for lowering the total costs of production. This study aimed to produce biosurfactants using Rhizopus arrhizus UCP 1607, with crude glycerol (CG) and corn steep liquor (CSL) as substrates. In addition, the biomolecule was characterized, and its efficiency in removing petroderivatives from marine soil was investigated. RESULTS: A 22 factorial design was applied, and the best condition for producing the biosurfactant was determined in assay 4 (3% CG and 5% CSL). The biosurfactant reduced the surface tension of water from 72 to 28.8 mN/m and produced a yield of 1.74 g/L. The preliminary biochemical characterization showed that the biosurfactant consisted of proteins (38.0%), carbohydrates (35.4%), and lipids (5.5%). The compounds presented an anionic character, nontoxicity, and great stability for all conditions tested. The biomolecule displayed great ability in dispersing hydrophobic substrates in water, thereby resulting in 53.4 cm2 ODA. The best efficiency of the biosurfactant in removing the pollutant diesel oil from marine soil was 79.4%. CONCLUSIONS: This study demonstrated the ability of R. arrhizus UCP1607 to produce a low-cost biosurfactant characterized as a glycoprotein and its potential use in the bioremediation of the hydrophobic diesel oil pollutant in marine soil

Micosis rino-orbito-cerebral: coinfección por Aspergillus sclerotiorum y Rhizopus microsporum en un huésped inmunosuprimido. Reporte de un caso / Rhino-orbital-cerebral mycoses: Aspergillus sclerotiorum infection and Rhyzopus microsporum in an immunosuppres sed host. A case report

Las micosis rino-cerebral, rino-orbito-cerebral y sinusopulmonar ocasionadas por especies de Mucorales y de Aspergillus se constituyen como una causa importan te de infección fúngica invasora asociada a una mortalidad mayor al 30%. La coinfección por dos o más especies en la forma rino-orbito-cerebral es infrecuente. Se describe un paciente con linfoma no Hodgkin, expuesto a múltiples esquemas quimioterápicos, en remisión completa, que presentó micosis con compromiso rino-orbito-cerebral por Aspergillus sclerotiorum y Rhizopus microsporum de rápida progresión con necesidad de tratamiento quirúrgico agresivo y terapia anti fúngica sistémica y local.

Rhino-orbital-cerebral and pulmonary mycosis caused by Mucorales and Aspergillus species have become an important cause of invasive fungal infection, with a 30% overall mortality rate. Rhino-orbital-cerebral disease caused by two or more species is uncommon. We present a patient with non-Hodgkin lymphoma, ex posed to aggressive chemotherapy, under complete remission, with acute onset of rhino-orbital-cerebral disease caused by Aspergillus sclerotiorum and Rhizopus microsporum, treated with aggressive surgery and both local and systemic antifungal therapy.

Mucormicosis Rinocerebral asociado a Cetoacidosis diabética / Rhinocerebral Mucormycosis associated to diabetic ketoacidosis

Mucormycosis is an infrequent fungal infection This infection is difficult to diagnose and treat and have a high morbility and mortality and affects immunocompromised patients, especially those patients with decompensated diabetes mellitus. We report the case of a 60 years old diabetic patient with poor metabolic control who was admitted for diabetic ketoacidosis and days later present right periorbital swelling and pain, is diagnosed of mucomycosis and is successfully treated with amphoterin B and surgery.

Growth modeling to control (in vitro) Fusarium verticillioides and Rhizopus stolonifer with thymol and carvacrol / Modelización del crecimiento in vitro para controlar Fusarium verticillioides y Rhizopus stolonifer con timol y carvacrol

The aim of this study was to evaluate the antifungal activity (in vitro) of thymol and carvacrol alone or in mixtures against Fusarium verticillioides and Rhizopus stolonifer, and to obtain primary growth models. Minimal inhibitory concentration (MIC) was evaluated with fungal radial growth with thymol or carvacrol concentrations (0-1600mg/l). Mixtures were evaluated using concentrations below MIC values. Radial growth curves were described by the modified Gompertz equation. MIC values of carvacrol were 200mg/l for both fungi. Meanwhile, MIC values of thymol were between 500 and 400mg/l for F verticillioides and R. stolonifer, respectively. A synergistic effect below MIC concentrations for carvacrol (100mg/l) and thymol (100-375 mg/l) was observed. Significant differences (p <0.05) between the Gompertz parameters for the antimicrobial concentrations and their tested mixtures established an inverse relationship between antimicrobial concentration and mycelial development of both fungi. Modified Gompertz parameters can be useful to determine fungistatic concentrations.

El objetivo de este trabajo fue evaluar la actividad antifúngica in vitro del timol y del carvacrol, solos o en mezclas, contra Fusarium verticillioides y Rhizopus stolonifer, y obtener modelos primarios de crecimiento. Se evaluó la concentración inhibitoria mínima (CIM) con el crecimiento radial, se ensayaron concentraciones de timol y carvacrol de 0 a 1.600 mg/l. Las mezclas se evaluaron utilizando concentraciones por debajo de los valores de CIM. Las curvas de crecimiento radial fueron descritas por la ecuación de Gompertz modificada. Se obtuvieron los siguientes valores de CIM: carvacrol, 200 mg/l para las 2 especies; timol, 500 mg/l y 400 mg/l para F. verticillioides y R. stolonifer, respectivamente. Se observó un efecto sinèrgico a concentraciones inferiores a las CIM para el carvacrol (100mg/l) y el timol (100-375 mg/l). Hubo diferencias significativas (p <0,05) entre los parámetros de crecimiento de Gompertz; se estableció que existe una relación inversa entre la concentración de los antimicrobianos y el desarrollo del micelio de ambos hongos.

Bioconversion of waste cooking oil glycerol from cabbage extract to lactic acid by Rhizopus microsporus

Abstract Glycerol from spent oil was processed by transesterification for biodiesel production. Although glycerol contains many types of impurities, it can be used as a C-source for lactic acid production by fungi, such as Rhizopus microsporus. In this study, we found that wild type R. microsporus (LTH23) produced more lactic acid than the mutant strains on cabbage glycerol media (CG media). More lactic acid was produced on CG media than on cabbage extract media (C media) by about two-fold in batch fermentation conditions. In addition, we found that lactic acid production in a fed-batch process was also slightly higher than in a batch process. To study the combined effects of pH, urea, and glycerol waste concentration on lactic acid production, a response surface methodology was used. The optimum pH, urea, and glycerol waste concentrations were pH 6.5, 3.75 g/L, and 17 g/L, respectively. The maximum lactic acid production predicted by this equation model was 4.03 g/L.

Production of flavor compounds from olive mill waste by Rhizopus oryzae and Candida tropicalis

Abstract The purpose of this study was to investigate the production of flavor compounds from olive mill waste by microbial fermentation of Rhizopus oryzae and Candida tropicalis. Olive mill waste fermentations were performed in shake and bioreactor cultures. Production of flavor compounds from olive mill waste was followed by Gas Chromatography–Mass spectrometry, Gas chromatography- olfactometry and Spectrum Sensory Analysis ®. As a result, 1.73-log and 3.23-log cfu/mL increases were observed in the microbial populations of R. oryzae and C. tropicalis during shake cultures, respectively. C. tropicalis can produce a higher concentration of d-limonene from olive mill waste than R. oryzae in shake cultures. The concentration of d-limonene was determined as 185.56 and 249.54 µg/kg in the fermented olive mill waste by R. oryzae and C. tropicalis in shake cultures respectively. In contrast, R. oryzae can produce a higher concentration of d-limonene (87.73 µg/kg) d-limonene than C. tropicalis (11.95 µg/kg) in bioreactor cultures. Based on sensory analysis, unripe olive, wet towel, sweet aromatic, fermented aromas were determined at high intensity in olive mill waste fermented with R. oryzae meanwhile olive mill waste fermented with C. tropicalis had only a high intensity of unripe olive and oily aroma.

Fulminant auricular mucormycosis in a diabetic patient

Human mucormycosis is an atypical fungal infection that commonly affects the skin, but rarely the auricular region. A 32-year-old diabetic woman, agricultural worker, was admitted with swelling, redness and mild signs of epidermolysis of the left ear, associated with intense pain, facial paralysis and septic signs. The ear cellulitis evolved into necrosis of the same region on the following day. Surgical debridement was performed and antimycotic therapy was started with poor response. The patient died in 48h. Culture was confirmatory for Rhizopus sp. (AU)

Cutaneous mucormycosis in advanced HIV disease

ABSTRACT Angionvasive mucormycosis is an emerging fungal disease known to affect mainly diabetics or subjects with profound neutropenia. Infection usually occurs through the inhalation route, but cutaneous inoculation may occur after trauma or burns. However, mucormycosis remains unusual in HIV infection. We report a fatal case of cutaneous mucormycosis due to Rhizopus arrhizus involving the scalp following herpes zoster infection. The patient was a 42-year-old man with advanced AIDS failing on salvage antiretroviral therapy. The fungus was diagnosed on the basis of histopathology and culture. Our case emphasizes the need to consider mucormycosis in the differential diagnosis of necrotic cutaneous lesions in patients with late-stage HIV disease.

Atividade antifúngica, in vitro, do óleo de café verde / Antifungal activity, in vitro, of the green coffee oil

O objetivo deste trabalho foi avaliar o efeito do contato direto e da fração volátildo óleo de café verde, testado nas concentrações de 500, 1.000, 1.500 e 2.000 µL L-1, sobre o crescimento micelial e a esporulação dos fungos Penicillium roqueforti e Rhizopus stolonifer. O óleo essencial de cravo-da-índia na concentração de 800 µL L-1 foi utilizado para comparação. Nas concentrações de 1.500 e 2.000 µL L-1, o óleo de café verde em contato direto proporcionou redução da esporulação do fungo R. stolonifer , sendo estatisticamente semelhante ao óleo de cravo-da-índia. Na fração volátil do óleo de café verde, observou-se redução significativa da esporulação de P. roqueforti e R. stolonifer na concentração de 2.000 µL L-1. O óleo de café verde, em contato direto ou por volatilização, reduziu significativamente o crescimento micelial e a esporulação de ambos os fungos em comparação com a testemunha.(AU)

The objective of this study was to evaluate the effect of direct contact and volatile fraction of from green coffee oil, tested at concentrations of 500, 1,000, 1,500 and 2,000 µL L-1, on mycelial growth and sporulation of Penicillium roqueforti and Rhizopus stolonifer . The essential oil of clove at a concentration of 800 µL L-1 was used for comparison. At concentrations of 1,500 and 2,000 µL L-1, the green coffee oil in direct contact caused a reduction of sporulation for R. stolonifer, similar to clove oil. In the volatile fraction of the green coffee oil, there was a significant reduction in sporulation of P. roqueforti and R. stolonifer at a concentration of 2,000 µL L-1. The green coffee oil, in direct contact or by volatilization, significantly reduced the mycelial growth and sporulation of both fungi compared to the control.(AU)

Cutaneous mucormycosis of scalp and eyelids in a child with type I diabetes mellitus.

Scalp mucormycosis in children is extremely rare. We present a case of pediatric scalp mucormycosis caused by Rhizopus oryzae in a 9-year-old diabetic girl who was successfully diagnosed and treated with amphotericin B deoxycholate and wound debridement. At 3 months follow up, the patient was stable although she had lost her vision.

Functional Properties of Filamentous Fungi Isolated from the Indonesian Fermented Dried Cassava, with Particular Application on Poultry

The study aimed to evaluate the probiotic properties, antioxidant activity and fermentative capacity of Acremonium charticola and Rhizopus oryzae isolated from the Indonesian fermented dried cassava, with particular application on poultry. A. charticola inhibited the growth of Escherichia coli and Aspergillus flavus. A. charticola and R. oryzae grew in potato dextrose agar (PDA) adjusted to pH 3 and 8 or in PDA supplemented with bile salt up to 0.8%. After soaking for 8 hr, the survival rate of A. charticola in the simulated gastric juice (pH 2) and bile solutions (2% bile salt) was lower than that of R. oryzae. A. charticola and R. oryzae exhibited strong antioxidant activities. Compared to unfermented cassava pulp (control), the fibre content of cassava pulp tended to be lower after fermentation with A. charticola for 14 days. The populations of A. charticola and R. oryzae were significantly higher in fermented cassava pulp than in unfermented one. Coliform was higher in cassava pulp fermented with R. oryzae or A. charticola + R. oryzae compared to control after 7 days of fermentation, however, the bacteria were not different between A. charticola-fermented cassava pulp and control. Lactic acid bacteria (LAB) were higher in A. charticola- and R. oryzae-fermented cassava pulp than those in control, however, no difference of LAB was observed between A. charticola + R. oryzae-fermented cassava pulp and control. In conclusion, A. charticola exhibited antibacterial, antifungal and antioxidant activity, gastrointestinal persistence and fermentative capacity that may be beneficial for poultry industry.

Construction of an integration vector carrying hygromycin B resistance gene and its genetic transformation in Rhizopus oryzae / 生物工程学报

To construct a system of genetic transformation suitable for Rhizopus oryzae, we constructed a single-exchange vector pBS-hygro carrying hygromycin B resistance gene (hph) as its selective marker using gene splicing by overlap extension PCR (SOE PCR) technique. We introduced this recombinant vector into Rhizopus oryzae AS 3.819 by PEG/CaCl2-mediated transformation of protoplast, electroporation of protoplast and germinated spores; and we studied the effects of hydrolysis time, field strength and spore germination time on transformation frequency. We conducted quantitative real-time PCR (qPCR) assay to determine the gene copy number of ldhA integrated in the genome of R. oryzae transformants and its effect on the stability of transformants. We successfully achieved R. oryzae transformants integrated with pBS-hygro-ldhA vector. The optimal hydrolysis time for protoplast production was 140 min, and the optimal field strength of electroporation pulse for protoplast was 13 kV/cm. The optimal germination time of spores for electroporation was 2.5 h, and the optimal field strength of electroporation pulse was 14 kV/cm. The transformation frequency of method based on germinated spores was generally higher than the methods based on protoplast. The qPCR test results suggested that transformants with high copy number of integration in a certain range were relatively stable. Our results provided basis and support for metabolic regulation and genetic engineering breeding of R. oryzae.

A Case of Cutaneous Mucormycosis Occurring after Systemic Steroid Therapy / 대한의진균학회지

Cutaneous mucormycosis is a rare disease caused by zygomycetes such as Rhizomucor, Mucor, Absidia, and Rhizopus. The disease usually occurs in immunocompromised individuals, and the organism is rarely pathogenic in an immunocompetent host. Herein, we report a 77-year-old female patient who had multiple erythematous papules and pustules on the left 3rd finger. She had received systemic steroid therapy prior to the occurrence of the skin lesions. The histopathological examination of Periodic Acid Schiff stained section showed chronic granulomatous inflammation and fungal hyphae. Rhizopus species was isolated on the fungal culture of the tissue specimen. The patient was finally diagnosed with cutaneous mucormycosis and was treated with itraconazole.

Utilização de três métodos imuno-histoquímicos na detecção de aspergilose e zigomicose em animais / Usage of three immunohistochemical methods in the detection of aspergillosis and zygomycosis in animals

Visando a otimização do uso da técnica de imuno-histoquímica (IHQ) na detecção de Aspergillus spp. e zigomicetos (membros da família Mucoraceae), utilizaram-se dois anticorpos monoclonais fungo-específicos em fragmentos de tecidos de animais (fixados em formol e embebidos em parafina) com diagnóstico histomorfológico prévio de aspergilose e zigomicose, os quais foram submetidos a três sistemas de detecção diferentes (dois biotinilados e um não biotinilado). Os dois anticorpos apresentaram alta especificidade e sensibilidade nos tecidos examinados. Não ocorreram reações cruzadas entre os anticorpos utilizados e os agentes etiológicos avaliados (incluindo casos de aspergilose, zigomicose, candidíase e pitiose). No entanto, reações inespecíficas foram observadas nas hifas em alguns casos, as quais puderam ser eliminadas através de um dos métodos de detecção utilizados. Para a aspergilose, o método da estreptavidina-biotina-fosfatase alcalina não apresentou reações inespecíficas nas hifas. Enquanto que nos casos de zigomicoses, as reações inespecíficas não ocorreram no método por polímero (não biotinilado). A técnica de IHQ mostrou-se uma ferramenta muito útil na detecção e confirmação dos casos de aspergilose e zigomicose neste estudo retrospectivo.

Aiming to optimize the usage of the immunohistochemical technique (IHC) in the detection of Aspergillus spp. and zygomycetes (members of the Mucoraceae family), two fungal-specific monoclonal antibodies were used in tissue fragments (formalin-fixed paraffin-embedded), previously diagnosed by histomorphology as aspergillosis and zygomycosis. Tissues were submitted to three different detection systems (two biotinilated and one non biotinilated). Both antibodies showed high specificity and sensitivity in the examined tissues. No cross-reactions were observed between the antibodies used and the agents evaluated (including cases of aspergillosis, zygomycosis, candidiasis and pythiosis). However, nonspecific reactions in hyphae were observed in some cases, but were eliminated by mean of one of the detection systems used. In the aspergillosis cases, with the streptavidin-biotin-alkaline phosphatase method, nonspecific reactions were not observed. In the zygomycosis cases, nonspecific reactions did not occur using a polymer (nonbiotinilated). The IHC technique showed to be a useful tool detecting and confirming aspergillosis and zygomycosis in this retrospective study.

Fermented soybeans by Rhizopus oligosporus reduce femoral bone loss in ovariectomized rats

BACKGROUND/OBJECTIVES: Soy isoflavones are structurally similar to estrogen and bind to estrogen receptors, suggesting that they exhibit estrogenic activities; therefore, they are referred to as phytoestrogens. Fermentation may affect the bioavailability of isoflavones altering soy isoflavone glycosides in the form of aglycones. Thus, this study investigated the effects of fermented soybeans by Rhizopus oligosporus on bone metabolism in both young rats as a pilot test and in ovariectomized (ovx) old rats as a model of menopause. MATERIALS/METHODS: In the pilot test, a total of 24 seven-week-old female Sprague-Dawley (SD) rats were fed one of three diets for a period of four weeks: casein, unfermented soybean product, or fermented soybean product by R. oligosporus. In the ovx rat model, 20-week-old SD rats weighing 260-290 g underwent either sham-operation (n = 10) or bilateral ovariectomy (n = 30) and were then fed the AIN-93M diet for one week. Thereafter, rats were fed sham-casein, ovx-casein, ovx-soybean, or ovx-fermented soybean diet for five weeks. After decapitation, femoral bones were isolated and preserved in 9% formalin for assessment of bone mineral density (BMD), bone mineral content (BMC), and bone-breaking strength (BBS). RESULTS: Ovx rats showed significantly increased weight gain and decreased uterine wet weight. Of particular interest, ovx rats fed fermented soybeans showed increased uterine wet weights compared to control rats. Fermented soybean diet caused a significant increase in plasma 17-beta estradiol concentrations in young rats, and 17-beta estradiol levels were enhanced in ovx rats to match those of sham-operated ones. Significantly lower femoral BMD and BMC were observed in ovx rats compared to sham-operated controls, whereas bone areas did not differ statistically among the groups. In addition, BBS tended to be increased in ovx rats fed soybeans and fermented soybeans. CONCLUSIONS: Supplementation of fermented soybeans could have preventive and therapeutic effects against osteoporosis in postmenopausal women.

Fatal Pulmonary Mucormycosis Caused by Rhizopus microsporus in a Patient with Diabetes

No abstract available.

Enhanced thermostability of Rhizopus chinensis lipase by error-prone PCR / 生物工程学报

Directed evolution was conducted to improve the thermostability of lipase from Rhizopus chinensis CCTCC M201021. Mutations were introduced by two rounds of error-prone PCR and mutant lipase was selected by fast-blue RR top agar screening. Two positive variants were selected in the first-round and four in the second-round screening process. Ep2-4 was proved as the most thermostable lipase and its DNA sequencing revealed three amino acid substitutions: A129S, P168L and V329A. Compared with the parent, its half-life at 60 degrees C was 5.4- times longer and T50 was 7.8 degrees higher. Purified lipase of Ep2-4 was characterized and the result shows that its thermostability improved without compromising enzyme activity. According to the mimicked protein structure, mutation A129S formed a hydrogen bond with Gln133 and improved the thermostability by increasing the hydrophilicity and polarity of protein; mutation P168L by forming a hydrophobic bond with the nearby Leu164.