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Xylitol (C 5 H 12 O 5 ) is a non-carcinogenic polyalcoholic sugar. Xylitol is beneficial for diabetics because it can be metabolized without insulin. Corn cobs contain 30% xylose which can be fermented into xylitol by microorganisms. Xylitol can be produced by fermentation of xylose and few microorganisms. Meyerozyma caribbica is a yeast that has been proven to produce xylitol and inhibitor’s resistant. The aim of this research is to test the xylitol productivity by Meyerozyma caribbica InaCC Y67 using corn cobs hydrolyzate and the effect of the volume of fermentation media on xylitol productivity by Meyerozyma caribbica InaCC Y67. The method was carried out by culturing Meyerozyma caribbica InaCC Y67 as a starter on YPD media. Fermentation using 100 mL Erlenmeyer with the variation of fermentation volume is 10 ml and 75 ml, agitation 175 rpm and 30 o C. Parameters were measured based on the dry weight of cells, xylose and xylitol. Data were analyzed using fermentation kinetics. The results of analysis showed that the higher xylitol production was found in the fermentation volume 75 ml with an efficiency value of 7,171%. The highest xylitol production was at the 48th hour with production value of 2.050 g/L. Results from research shows that Meyerozyma caribbica InaCC Y67 can produce xylitol with corn cobs hydrolyzate. The right volume of fermentation in the fermentation process can also increase the productivity of xylitol.

Moloney murine leukemia virus reverse transcriptase (MMLV-RT) is the most frequently used enzyme in molecular biology for cDNA synthesis. To date, reverse transcription coupled with Polymerase Chain Reaction, known as RT-PCR, has been popular as an excellent approach for the detection of SARS-CoV-2 during the COVID-19 pandemic. In this study, we aimed to improve the enzymatic production and performance of MMLV-RT by optimizing both codon and culture conditions in E. coli expression system. By applying the optimized codon and culture conditions, the enzyme was successfully overexpressed and increased at high level based on the result of SDS-PAGE and Western blotting. The total amount of MMLV-RT has improved 85-fold from 0.002 g L

Sugarcane trash (ST) is an abundant but underused biomass left in the field when the sugarcane is harvested. However, there are only a few studies to evaluate pretreatment of the residual bioresources for enzymatic saccharification. In this study, we aimed to explore the effects of combined severity factor (CSF), resulted from the use of different acids (phosphoric, maleic, and oxalic acids) on the pretreatment efficiency in microwave (MW)-accelerated process. The effects of acids and CSF on pretreated biomass properties and sugars obtained in the pretreatment soluble fraction and in enzymatic hydrolysate were evaluated. The degree of crystallinity of biomass pretreated at the same CSF is different due to different of acids used, and it did not correlate with the sugars obtained in the hydrolysate after enzymatic saccharification. MW-assisted acid pretreatment of ST at CSF of 2.05 affected functional groups and morphology of the biomass significantly. ST exposed to the same severity (CSF 2.05) using different acids resulted in reducing sugars yield 25.3–30.8% (based on initial biomass) from the pretreatment soluble fraction and 26.1–28.8% (based on initial biomass) from enzymatic hydrolysis, with the highest (30.8% and 28.8%) when used maleic acid. We succeeded in the production of total reducing sugars by 59.6% yield (of initial biomass) from recalcitrant sugarcane trash by applying MW-assisted maleic acid pretreatment at CSF of 2.05. The work provided insights into the use of organic acid as the catalyst in MW-accelerated process and can be further developed for application in pretreatment of ST in industry. Graphical abstract

Fatimah, Suroiyah F, Solikha N, Rahayuningtyas ND, Surtiningsih T, Nurhariyati T, Ni’matuzahroh, Affandi M, Geraldi A, Thontowi A. 2022. Antimicrobial activity of actinomycetes isolated from mangrove soil in Tuban, Indonesia. Biodiversitas 23: 2957-2965. This study aims to isolate, identify, and investigate the antimicrobial activity of actinomycetes isolated from mangrove soil of the Mangrove Center Tuban in Jenu Village, Tuban District, Indonesia. Soil sampling was carried out with a purposive sampling technique. The dry-heating and pour plate methods were used to isolate actinomycetes. Four isolates (LIB.2; LIA.4; LIA.9; and LIA.10) were selected and tested for their antimicrobial activities against Escherichia coli ATCC 25922, Staphylococcus aureus ATCC 25923, and Candida albicans ATCC 10231 using disc diffusion method. Colony morphology characterization and Gram staining were then conducted on the 4 isolates. The identification of LIB.2 was performed by biochemical assay and 16S rRNA gene sequence analysis. The results showed that crude antimicrobial extracts (CACs) of all isolates inhibited the growth of E. coli but not S. aureus and C. albicans. Isolate LIB.2 showed the highest inhibition zone with a diameter of 15,65 ± 2,33 mm, followed by LIA.9 (10,19 ± 2,78 mm), LIA.4 (9,80 ± 0,47), and LIA.10 (8,75 ± 0,42 mm). The most potential isolate was identified as a member of Streptomyces genera. Based on biochemical assay and 16S rRNA gene sequence analysis, LIB.2 was identified as Streptomyces vellosus strain LIB.2.

Indonesia is one of the biggest cocoa producers in the world with total production 240,000 tons by 2019. Meanwhile, we have about 400,000 tons cocoa pod husk (CPH). CPH biomass is a serious problem in Indonesia, but at the same time, it is also an important, challenging, and environmental renewable source for bioproduction. Therefore, it becomes a focus of interest in this research aiming to utilize of CPH as renewable substrate for citric acid production. The solid-state fermentation (SSF) approach was applied to CPH using Aspergillus niger Tiegh F359 for produce citric acid. Response surface methodology (RSM) was used to optimize the citric acid production with water concentration, nitrogen concentration, and fermentation time as variable factors. Around 7530 ppm citric acid was produced from 1 g CPH as a carbon source. Entirely, this study has succeeded in optimizing citric acid production by using SSF using A. niger Tiegh F359 and providing a fundamental study for CPH as low-cost renewable substrate for bioproduct production and future endeavors.

A two-stage selection process was applied to eight oleaginous yeast strains from the Lipomyces genera. In the primary selection stage, a nitrogen-limited mineral medium (-NMM) that contained a mixture of glucose and xylose as a carbon source was used to evaluate the lipid-accumulating abilities of the yeast strains. The strains L. doorenjongii, L. orientalis, and L. starkeyi were selected as the potential strains in the primary selection. These three strains exhibited a remarkable ability to simultaneously assimilate glucose and xylose and achieved a cell biomass of more than 30 g/L. The values for lipid content in the selected strains were 57.89 ± 1.92, 56.38 ± 1.93, and 77.14 ± 1.55% for L. doorenjongii, L. orientalis, and L. starkeyi, respectively. In the secondary selection, when the -NMM medium contained an inhibitory chemical compound (ICC), the selected strains showed a different tolerance level against each of the typical inhibitor compounds. However, L. starkeyi accumulated the highest lipid content and yield at 68.24 ± 2.48% and 0.19 ± 0.00 (w/w), respectively. L. starkeyi accumulated high levels of intracellular lipid and tolerated the ICC. The composition of fatty acid methyl esters (FAMEs) was unaltered by the presence of ICC and the major FAMEs consisted of oleic, palmitic, stearic, palmitoleic and linoleic acids.

The expensive price of glucoamylase is due to the high cost of enzyme production. Utilization biomass is expected to be an alternative raw material to reduce the cost of producing enzymes without reducing the quality of the product. Aspergillus awamori KT-11 is known to be able to produce glucoamylase by utilizing biomass waste. This study aimed to optimize glucoamylase production from A. awamori KT-11 by utilizing cassava peel as an alternative substrate with variation nitrogen source through Submerged Fermentation (SmF). Variables carry out in this study were the concentration of cassava peel (5-30%), nitrogen sources (casein hydrolyzate, yeast extract and sodium nitrate). The results showed in the concentration of cassava peels and nitrogen sources affect glucoamylase production. The optimum glucoamylase activity was 3984,935 U/L in 10% of cassava peel in medium. The other results showed different sources of nitrogen significantly influence glucoamylase production. The addition of yeast extract increased glucoamylase activity to 4617,894 U / L. Keywords: Aspergillus awamori KT-11, glucoamylase, cassava peel, submerged fermentation (SmF) ABSTRAK Bahan baku yang mahal dalam produksi glukoamilase mengakibatkan harga jual glukoamilase tinggi. Pemanfaatan biomassa tinggi karbohidrat diharapkan dapat menjadi alternatif bahan baku untuk menurunkan biaya produksi enzim tanpa menurunkan kualitas dari produk yang dihasilkan. Aspergillus awamori KT-11 diketahui mampu memproduksi glukoamilase dengan memanfaatkan limbah biomassa. Tujuan penelitian ini adalah optimasi produksi glukoamilase dari A. awamori KT-11 dengan memanfaatkan limbah kulit singkong sebagai substrat alternatif dengan berbagai sumber nitrogen melalui Submerged Fermentation (SmF). Variabel yang dilakukan pada penelitian ini yaitu konsentrasi kulit singkong (5-30%), sumber nitrogen (kasein hidrolisat, yeast extract dan natrium nitrat). Hasil riset menunjukkan konsentrasi kulit singkong dan jenis sumber nitrogen mempengaruhi produksi glukoamilase. Aktivitas glukoamilase optimum diidentifikasi ketika konsentrasi substrat kulit singkong sebesar 10% yaitu 3984,935 U/L. Penambahan sumber nitrogen yang berbeda mempengaruhi produksi glukoamilase secara signifikan. Penambahan yeast extract meningkatkan aktivitas glukoamilase menjadi 4617,894 U/L. Kata kunci: Aspergillus awamori KT-11, glukoamilase, kulit singkong, submerged fermentasi (SmF)

The toxic fermentation inhibitors in lignocellulosic hydrolysates pose significant problems for the production of second-generation biofuels and biochemicals. Among these inhibitors, 5-(hydroxymethyl)furfural (HMF) and furfural are specifically well known. This study investigated the furfural and 5-HMF tolerance in Candida strains, which could be used for the development of advanced generation bioethanol processes. The 10 isolates of Candida were selected based on the cell growth and bioethanol production on YPD medium containing several concentrations of furfural and 5-HMF by using spectrophotometer and HPLC. Candida parapsilosis Y80 could grow and produce bioethanol in the medium that contains furfural and 5-HMF with a concentration of 60 mM and 40 mM, respectively. Based on the results, C. parapsilosis Y80 has potential activity in the development of bioethanol fermentation.

Oleaginous microbes can convert substrates such as carbon dioxide, sugars, and organic acids to single-cell oils (SCOs). Among the oleaginous microorganisms, Lipomyces starkeyi is a particularly well-suited host given its impressive native abilities, including the capability to utilize a wide variety of carbon sources. In this work, the potential of L. starkeyi NBRC10381 to produce SCOs in a synthetically nitrogen-limited mineral medium (-NMM) was investigated by differing the inoculum size using glucose and/or xylose as a carbon source. Fermentation using glucose and xylose as mixed carbon sources generated the highest production of biomass at 40.8 g/L, and achieved a lipid content of 84.9% (w/w). When either glucose or xylose was used separately, the totals for achieved lipid content were 79.6% (w/w) and 85.1% (w/w), respectively. However, biomass production was higher for glucose than for xylose (30.3 vs. 28.7 g/L, respectively). This study describes the first simultaneous achievement of higher levels of cell mass and lipid production using glucose and/or xylose as the carbon sources in different inoculum sizes.

D-Xylitol is a five-carbon sugar alcohol, which can be obtaines from xylose of agriculutural wastes with microbial fermentation. The inhibitory chemical complexes (ICC) were founded after biomass pretreatment step. The ICC in acid hydrolysate can inhibit microbial metabolism in the medium. Several methods for detoxification; adsorption by activated charcoal, by ion exchange resin or by using enzymes. This study aims to evaluate the effect of using charcoal in xylitol fermentation by using lignocellulosic hydrolisate. In this work, detoxification process by added 1% activated charcoal to reduce the inhibitors in corn cobs hydrolysate and sugarcane trash hydrolysate. The biomass hydrolysate was fermented by Meyerozyma caribbica Y67 to produce xylitol. It is expected that detoxification can reduce concentration of inhibitors, so that microbial growth is not inhibited and more product. The results showed that M. caribbica Y67 had not significant different between pure hydrolysate and detoxified hydrolysate with activated charcoal. We suggested that M. caribbica Y67 tolerance to ICC and potential for xylitol fermentation from lignocellulosic biomasses.

One of the rare types of pentose sugar is xylitol, which has various benefits in the field of food and medicine. Xylitol is one of the results of xylose fermentation and few microorganisms are able to produce it. Meyerozyma caribbica Y67 is one of the yeast collections of Indonesian Culture Collection (InaCC) which can produce xylitol. The production of xylitol about cell initiation and media volume gave different results for each factor. The fermentation conditions were using erlenmeyer 250 mL, agitation 150 rpm and 30ºC temperature. The parameters analyzed were dry cell weight (DCW), xylose, and xylitol. The results of this study showed that cell initiation with an optical density at 600 nm (OD600) = 5 (≍1.07x107 CFU or 3.980 g/L) had the highest efficiency in producing xylitol for 24 hours of fermentation, 51, 099%; specific growth rate (µ): 0.069. In the media volume variable, for 24 hours fermentation, the high-efficiency value of 20% volume erlenmeyer is 55, 708%; (µ): 0.082 and 48 hours fermentation is 40% volume erlenmeyer which is 71, 959%; (µ): 0.048. The research is expected to be used as a scale up recommendation for the industry.

Yetti E, Thontowi A, Yopi. 2016. Polyaromatic hydrocarbon degrading bacteria from the Indonesian Marine Environment.Biodiversitas 17: 857-864. Oil spills are one of the main causes of pollution in marine environments. Oil degrading bacteria play an important role for bioremediation of oil spill in environment. We collected 132 isolates of marine bacteria isolated from several Indonesia marine areas, i.e. Pari Island, Jakarta, Kamal Port, East Java and Cilacap Bay, Central Java. These isolates were screened for capability to degrade polyaromatic hydrocarbons (PAHs). Selection test were carried out qualitatively using sublimation method and growth assay of the isolates on several PAHs i.e. phenanthrene, dibenzothiophene, fluorene, naphtalene, phenotiazine, and pyrene. The fifty-eight isolates indicated in having capability to degrade PAHs, consisted of 25 isolates were positive on naphthalene (nap) and 20 isolates showed ability to grow in phenanthrene (phen) containing media. Further, 38 isolates were selected for dibenzothiophene (dbt) degradation and 25 isolates were positive on fluorene (flr). On the other hand, 23 isolates presented capability to degrade in phenothiazine (ptz) and 15 isolates could grow in media with pyrene (pyr). Based on homology analysis of partial 16S rDNA gene, we obtained six taxonomy classes of PAH degrading bacteria, namely α-Proteobacteria (31%), γ-Proteobacteria (43%), Firmicutes Bacilli (12%), Actinobacteria; Micrococcales (9%), Actinobacteria; Propionibacteriales (2%), and Bacteroidetes; Flavobacteriia (3%). In this research, we obtained diverse PAH degrading bacteria from marine areas.

Seven (R)-selective amine transaminases (R-ATAs) recently discovered by an in silico-based approach in sequence databases were produced recombinantly in Escherichia coli and subjected to partial purification by ammonium sulfate precipitation. A range of additives and various buffers were investigated to identify best conditions to ensure good storage stability and stable activity during biocatalysis. All enzymes show pH optima between pH 7.5―9. These R-ATAs were then applied in the asymmetric synthesis of twelve aliphatic, aromatic and arylaliphatic (R)-amines starting from the corresponding prochiral ketones using a lactate dehydrogenase/glucose dehydrogenase system to shift the equilibrium. For all ketones, at least one enzyme was found that allows complete conversion to the corresponding chiral amine having excellent optical purities >99% ee. Variations in substrate profiles are also discussed based on the phylogenetic relationships between the seven R-ATAs. Thus, we have identified a versatile toolbox of (R)-amine transaminases showing remarkable properties for application in biocatalysis.

The response surface method (RSM) was used to investigate the effects of bioethanol fermentation parameters, including sugarcane bagasse concentrations (0-5 % (w/v), enzyme types (cellulase and hemicellulase), enzyme concentrations (0-1 FPU/g biomass), medium pH, and incubation period. Bioethanol production was conducted by simultaneous saccharification and fermentation (SSF) of sugarcane bagasse hydrolyse using Saccharomyces cerevisiae BTCC 3. The experiment results showed that the maximum bioethanol production by using the SSF method was the same as RSM prediction. The optimum conditions for bioethanol production were 5% (w/v) of sugarcane bagasse, a mixture of cellulase and hemicellulase at 1 FPU/g of sugarcane bagasse for each enzyme, pH medium 6.0, and fermentation period 72 hours. The bioethanol yield of 2.43 g/L was obtained under these conditions.

β-Glucan is one of the most abundant polysaccharides in yeast Saccharomyces cerevisiae cell wall. The aim of this research is to explore an alternative nitrogen sources for β-glucan production. S. cerevisiae were grown in fermentation medium with different nitrogen sources. Peptone 2%, glutamic acid 0,5%, urea 0,2%, and diammonium hydrogen phosphate (DAHP) 0,02% were used for nitrogen source in the medium. A two liter air-lift fermentor was used in the fermentation process for 84 hours (T = 300C, pH 7, and 1.5 vvm for the aeration). During the fermentation, optical density, extraction of β-glucan, glucose and protein in hydrolisate cultured were determined. β-glucan production level is similar with the growth rate of yeast and followed by decreasing glucose and protein content in hydrolysis cultured. The highest and lowest β-glucan content were obtained from peptone (933.33 mg/L) and glutamic acid (633.33 mg/L) as a nitrogen source in cells cultured after fermentation completed respectively. Yeast cells cultured with urea and DAHP as a nitrogen source give the same content of β-glucan about 733.33 mg/L. β-glucan concentration produced in medium with urea was a higher than that produced using glutamic acid and DAHP as a nitrogen source. The result indicated that urea can be used as an alternative nitrogen source for the production of β-glucan. Urea is easily available and cheaper than peptone, glutamic acid and DAHP.

Dibenzothiophene (DBT) and its derivatives have been widely used as model organic sulfur compounds in petroleum, included their biodegradation process. The abilities of microorganisms to degrade pollutants are significantly influenced by various factors such as microbial species, nutrients and environmental parameters. In this research, we carried out further study to determine optimal condition for DBT biodegradation regarding with substrate and strains cell concentration by several indigenous marine bacteria from Indonesia. These three isolates were belong to Mauricauda olearia, Alcanivorax xenomutants, and Stakelama pacifica, with homology result 99% each. Optimal dibenzothiophene as substrate reached by all isolates is 100 ppm, while cell concentration or microbial numbers that gave highest growth for all isolates is 20 based on conversion of OD600 nm measurement.

The need of â-glucan is increasing in food, medicine and cosmetic industry, because it becomes anticancer,antitumor and antiaging, increases immunosystem, and decreases cholesterol content in blood. The cell walls ofS. cerevisiae contain 80-90% polysaccharides that posses â-glucan. This research was aimed to obtain appropriatecarbon sources to increase the production of â-glucan. The carbon sources used were glucose, glucose commercial,sucrose and molases. The fermentation process was done by using air lift fermentor. The steps of fermentatonincluded regeneration of S. cerevisiae strain, preculture, fermentor preparation and running fermentor for 84hours. Sampling of S. cerevisiae culture was determined the cell growth by optical density (OD) usingspectrophotometer UV/VIS at ë 550 nm. The protein content was determined by Lowry method at ë 755 nm and thetotal glucose was measured by phenol sulphate method at ë 490 nm. The measurement result of cell growthshowed that the high intensity of S. cerevisiae in medium contain molases, but it did not show significant effectwhen compare to other carbon sources. The protein and carbohydrate contain in medium tended to decrease. Theresult of â-glucan on glucose, sucrose, glucose commercial and molases were 933,3, 1100, 1000, and966,7 mg/l. It can be concluded that sucrose and glucose commercial can replace the glucose to produce of â-glucan, because they are cheaper and easier to get. Beside that, molases can be used as an alternative carbonsource because it can produce of â-glucan as well as glucose.