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Rahayu HM, Putri WA, Khasanah AU, Sembiring L, Purwestri YA. 2021. Indigenous Streptomyces spp. isolated from Cyperus rotundus rhizosphere indicate high mercuric reductase activity as a potential bioremediation agent. Biodiversitas 22: 1519-1526. The purification and characterization of mercuric reductase of four indigenous Streptomyces spp. from Cyperus rotundus L. rhizosphere in mercury-contaminated area have been investigated. Cell-free extract was obtained by disrupting cells using sea sand at 4 °C followed by centrifugation. Mercuric reductase was purified by ammonium sulfate precipitation, dialysis, and chromatography column (DEAE Sepharose anion column chromatography). The determination of optimum pH and temperature of mercuric reductase activity was measured based on the number of NADPH2 oxidized to NADP per mg protein per minute using a spectrophotometer. The molecular weight of mercuric reductase was determined using SDS-PAGE. Result showed that the highest specific activity of mercuric reductase was recorded from Streptomyces spp. BR28. The optimum pH and temperature of cell-free extract enzyme mercuric reductase were 7.5 and 80 °C, respectively. The enzyme was purified to 431.87-fold with specific activity 21918.95 U/mg protein. SDS PAGE showed that the molecular weight of mercuric reductase in Streptomyces spp. BR 28 ranged from 50 kDa to 75 kDa. It can be concluded that Streptomyces isolates contain mercuric reductase and have potential as mercury bioremediation agent to overcome mercury contamination in the environment.

Poly-β-hydroxybutyrate (PHB) is a thermoplastic polyester accumulated intracellularly by many microorganisms under unfavorable growth conditions. The features of PHB are biodegradable and biocompatible, and the physical properties are similar to polypropylene, which has attracted industrial attention as an environmentally degradable plastic for a wide range of agricultural, marine, and medical applications and appropriate substitutes for hydrocarbon-based plastics. Starch is a renewable carbon source from plant sources available abundantly in large quantities throughout the globe and has recently been used as a carbon source for PHB production. The utilization of starch in PHB production needs enzymatic hydrolysis for starch degradation since many microorganisms do not produce these enzymes natively. This suggests there is a need for exploitation of bacterial culture for the co-production of the starch-hydrolyzing enzyme (amylolytic bacteria) as well as PHB. Some bacteria have been reported capable to convert starch into PHB directly, which are from the genus Bacillus. The process of PHB production from starch by amylolytic bacteria is simultaneous saccharification and fermentation (SSF). The mechanism of bacteria synthesizing PHB from starch is divided into two groups, namely, the growth-associated PHB synthesis and the non-growth-associated PHB synthesis. The utilization of starch for PHB production is an economic strategy to reduce production costs of PHB as well as its applications in various fields.

Physicochemical properties of cellulose produced by local bacterial strain Gluconacetobacter xylinus KRE-65 by static and agitated fermentation methods was studied. Cellulose production by G. xylinus KRE-65 was carried out in coconut base medium with static and agitated fermentation methods. The dry weight, morphological and physicochemicalproperties of bacterial cellulose were compared based on SEM, XRD and FTIR analyses. The results showed that the G. xylinus KRE 65 in the static fermentation produced cellulose higher than agitated fermentation. Static fermentation method produced bacterial cellulose in the sheets form, while agitated fermentation produced fragmented cellulose with predominantly spherical shape. The observation of the surface structure of bacterial cellulose by SEM showed that the static fermentation method generated woven densely cellulose microfibrils, while agitated fermentation significantly changed the surface structure, namely woven microfibrils become more loose with formed larger and higher number of pores. The degree of crystallinity of bacterial cellulose by XRD analysis in static fermentation was 91%, agitated fermentation at 100 rpm was 73% and agitated fermentation at 150 rpm was 72%. FTIR spectra indicated that the pellicles produced by G. xylinus KRE 65 with static and agitated fermentation were found as cellulose. Cellulose produced from both fermentation methods showed different physicochemical properties, therefore they can be applied for different purposes in accordingly.Keywords: Gluconacetobacter xylinus, bacterial cellulose, static fermentation, agitated fermentation ABSTRAKSifat fisikokimiawi selulosa yang dihasilkan oleh strain lokal bakteri Gluconacetobacter xylinus KRE-65 dengan metode fermentasi statis dan agitatif telah diteliti. Produksi selulosa oleh G. xylinus KRE-65 dilakukan dalam media dasar air kelapa dengan metode fermentasi statis dan agitatif. Selulosa yang dihasilkan selanjutnya dibandingkan beratkering, bentuk morfologi dan sifat fisikokimiawinya menggunakan metode SEM, XRD dan FTIR. Hasil penelitian menunjukkan bahwa G. xylinus KRE 65 menghasilkan selulosa lebih tinggi pada metode fermentasi statis dibandingkan fermentasi agitatif. Metode fermentasi statis menghasilkan selulosa bakteri yang berbentuk lembaran sedangkan fermentasi agitatif menghasilkan selulosa yang terpecah-pecah dengan bentuk dominan bulat. Pengamatan struktur permukaan selulosa bakteri dengan SEM memperlihatkan bahwa metode fermentasi statis menghasilkan selulosadengan anyaman mikrofibril yang padat, sedangkan fermentasi agitatif menyebabkan terjadinya perubahan struktur permukaan yaitu melonggarnya anyaman mikrofibril dan terbentuknya pori-pori yang lebih besar dan lebih banyak. Derajat kristalinitas selulosa bakteri dengan analisis XRD pada metode fermentasi statis sebesar 91%, fermentasiagitatif 100 rpm sebesar 73% dan fermentasi 150 rpm sebesar 72%. Spektra FTIR mengindikasikan bahwa pelikel yang dihasilkan oleh G. xylinus KRE 65 pada kedua metode fermentasi tersebut merupakan selulosa. Selulosa yang dihasilkan dari fermentasi statis dan agitatif mempunyai sifat fisikokimiawi yang berbeda sehingga dapat diterapkandalam aplikasi yang berbeda sesuai dengan sifat fisikokimiawi yang dibutuhkan.Kata kunci: Gluconacetobacter xylinus, selulosa bakteri, fermentasi statis, fermentasi agitatif

The objective of this study was to determine the potential of LAB with phytate degrading activity from fermented traditional food grain-based and legume-based. Lactic acid bacteria were isolated from different sources of traditional fermented food from Gunungkidul Yogyakarta Indonesia such as gembus tempeh (tofu waste), soybean tempeh, lamtoro tempeh (Leucaena bean) and kara tempeh. Isolation of LAB was performed using Total Plate Count (TPC) on de Man Rogosa Sharpe Agar (MRSA) medium supplemented with CaCO3. They were screened for their ability to degrade myo-inositol hexaphosphate or IP6 by using qualitative streak platemethod with modified de Man Rogosa-MorpholinoPropanesulfonic Acid Sharpe (MRS-MOPS) medium contained sodium salt of phytic acid as substrate and cobalt chloride staining (plate assay) method. The selected isolates were further assayed for phytase activities using quantitative method with spectrophotometer and the two selected isolates growth were optimized. Furthermore, thhe isolates tha...

Bacterial resistance to heavy metal is a genetic and physiological adaptation to the environment which contaminated by heavy metal. Kalimas is an important river in Surabaya that is contaminated by some heavy metals and probably as a habitat for heavy metal resistance bacteria. Bacterial resistance to heavy metals are different for each species, and their diversity can be studied by phylogenetic taxonomy approach. Isolates screening was done using nutrient agar which contained 1 mg/L HgCl2, CdCl2 and K2Cr2O7. Bacterial viability were observed by nutrient broth which contained 10 mg/L HgCl2, 30 mg/L CdCl2 and 50 mg/L K2Cr2O7. Isolates that resistant to heavy metal and viable after exposure to heavy metal were identified using 16S rRNA gene marker by Polymerase Chain Reaction (PCR). Phylogenetic tree reconstruction was done by the neighbor-joining algorithm. Genetic assignment showed isolates that resist and viable after exposure of Hg, Cd and Cr are Bacillus S1, SS19 and DA11. Based on BLAST analysis from ...

Twenty seven strains of lactic acid bacteria (LAB) were isolated from bakasang, Indonesian traditional fermented fish product. In general, LAB have inhibitory activity againts pathogenic bacteria and spoilage bacteria. Screening for antimicrobia activity of isolates were performed with well-diffusion method. One isolate that was designed as Pediococcus BksC24 was the strongest against bacteria pathogenic and spoilage bacteria. This strain was further identified by 16S rRNA gen sequence comparison. Isolates LAB producing antimicrobial agents from bakasang were identified as Pediococcus acidilactici.Keywords : Bakasang, LAB, antimicrobial, phenotypic characteristics, 16S rRNA gene

Twenty six isolates of Streptomyces spp. obtained from Cyperus rotundus L. rhizosphere were tested forability to produce indole-3-acetic acid (IAA) in yeast malt extract (YM) medium containing 2 mg/mL tryptophan.Screening of the isolates for ability to produce IAA was carried out by adding Salkowski reagent in bacteriaculture and was measured quantitatively by spectrophotometer at λ 530 nm. Thin Layer Chromatography (TLC)method was used to determine IAA. To ensure the IAA production in Streptomyces isolates, gene involved inIAA biosynthesis was detected by amplifying Tryptophan Monooxigenase (iaaM) gene. The study of the effectof tryptophan on the production of IAA was measured at different concentrations of tryptophan (0, 1, 2, 3,4, 5 mg/mL) in the bacterial culture. The result showed that there were two Streptomyces spp. isolates whichcould produce IAA, namely the isolates of Streptomyces sp. MS1 (125.48 μg/mL) and Streptomyces sp. BR27(104.13 μg/mL). The TLC result showed that the compound in both isolates was identifi ed to be IAA. Theamplifi cation results showed that iaaM gene was detected in both isolates. This results indicated that the IAMpathway is predicted involved in the biosynthesis of IAA in the selected isolates. Both of the isolates were ableto produce IAA after 24 h incubation and the highest production was at 120 h incubation with the concentrationof tryptophan was 2 mg/mL dan 1 mg/mL, respectively. Therefore, it is concluded that Streptomyces spp.isolates are able to produce IAA and potentially to be utilized as biostimulat agent.Keywords: Streptomyces spp., indole-3-acetic acid (IAA), indole-3-acetamide (IAM), Tryptophan Monooxigenasegene (iaaM)

This study was carried out to analyze the suitability of the identification of four indigenous cellulose-producing acetic acid bacterial isolates (ANG29, KRE65, ANG32 and SAL53) based on the analysis of whole cellular protein profiles against identification based on phenotypic traits. Whole cellular protein profiles were determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) method. The whole cellular protein profiles obtained from sample isolates, were compared with reference isolates for species identification. The results showed that based on visual observations can be determined as much as 12 bands of protein with a molecular weight of 19,099 KDa up to 132.182 KDa. Based on the analysis of protein bands were detected visually, fourth indigenous cellulose- producing acetic acid bacterial isolates in the study had a higher similarity profile to the reference strain Gluconacetobacter xylinus BTCC 769 compared with other reference strains namely G. hansenii NBRC 14820T. This condition is consistent with the results of the identification of fourth cellulose producing acetic acid bacterial isolates based on phenotypic traits. Thus, the whole cellular protein profiles by SDS-PAGE technique can be used as a one of method to identification of cellulose producing acetic acid bacterial isolates.

A considerable amount of methylformate accumulated in the culture medium of methanol-grown methylotrophic yeasts. Methylformate is considered as an intermediate in a novel formaldehyde oxidation pathway. Through investigations with Pichia methanolica, methylformate formation was found to be catalysed by a new type of alcohol dehydrogenase, which was named methylformate synthase. When cells were grown on a relatively high concentration of methanol or exposed to a high concentration of formaldehyde, formation of methylformate was enhanced and the level of methylformate synthase in the cells increased. How methylformate synthase is involved in formaldehyde oxidation and formaldehyde detoxification is discussed.

A new bacterial strain that produces amylase and poly-α-hidroxybutyrate (PHB) using sago starch as carbon source was characterized and identified to be member of the Bacillus megaterium group based on phenotypic characteristics and 16S rDNA gene sequences. Amylase activity was determined spectrophotometrically on the basis of substrate concentration reduction. PHB production was quantified with UV spectrophotometer. The polymer produced by B. megaterium PSA10 was identified by Fourier Transform Infrared spectroscopy (FTIR). The result of the study showed that the amylase specific activity B. megaterium PSA10 was 593,61 DUN/mg protein and PHB production from sago starch was 52,28 % of cell dry weight (CDW). FTIR analysis of the polymer indicated that the strain B.megaterium PSA10 was a potent PHB producer.

The purpose of the reasearch is to determine of antifungal activity from chitinase from Streptomyces RKt5 to inhibite growth of Fusariumoxysporum. The chitinase of Streptomyces RKt5 produced in liquid chitin medium with optimum conditions (inoculum concentration, pHand incubation time) and then partially purified with ammonium sulphate. The enzyme products were tested the antifungal activity againstF.oxysporum. The results showed that mycelial growth of F.oxysporum can be inhibited by Streptomyces RKt 5 in dual culture test. Thepartial purified chitinase enzyme couldn’t inhibit the fungal growth. But if the mycellium fragmented, the enzyme could degrade the fungalcell wall in incubation time. The frequency of fungal cell wall lysis and levels of N-acetylglucosamine released that have been increasingalong with the length of incubation time.