Acetobacter Sp Research Articles

Revealing the synergistic antibacterial mechanisms of resveratrol (RES) and pulsed electric field (PEF) against Acetobacter sp

In the wine industry, Acetobacter sp. is a typical spoilage microorganism responsible for increased volatile acids and wine spoilage. This study investigated the impact of combined treatment using varying concentrations of resveratrol (RES) and pulsed electric field (PEF) on the bactericidal efficacy, intracellular enzyme activities, and cellular metabolism of Acetobacter sp. The results from the Weibull mathematical model revealed a notable enhancement in the bactericidal effectiveness of the RES and PEF treatments with increasing RES concentration. In addition, the synergies between RES and PEF might not only resulted in the deactivation of Alcohol dehydrogenase (ADH) and Aldehyde dehydrogenase (ALDH) of Acetobacter sp., but also induced modifications in the secondary and tertiary structures of intracellular enzymes as evidenced by fluorescence, ultraviolet, fourier transform infrared, and circular dichroism spectra. Furthermore, metabolomics results showed that 1,910 metabolites exhibited differential expression, with 1,118 metabolites being down-regulated and 792 metabolites being up-regulated. After the synergies between RES and PEF, 17 biochemical pathways were significantly changed, mainly involving amino acid metabolism, carbohydrate metabolism, cofactor and vitamin metabolism, nucleotide metabolism, etc. These findings demonstrated that the combined treatment of RES and PEF can effectively suppress the growth of Acetobacter sp. and the inactivation mechanism of Acetobacter sp. by PEF in conjunction with RES was revealed.

Isolation, Characterisation and Identification of Bacteria from Three Different Unpasteurized Fruit Juices Sold at a Local Market in Guyana

Fruit juices are widely consumed for their nutritional value. However, fruit juices that are unpasteurised may be unsafe to drink because they are not subject to heat processing and much of their human handling results in contamination. The fruits used to make these juices have resident microflora, transient bacteria from handling and equipment, and bacteria from water used to wash fruits and in some cases make the juice. The objective of this research was to determine the bacteria present in unpasteurised passionfruit, cherry, and tamarind juices respectively. Through the use of a survey, and standard methods for isolation, identification and characterisation of bacteria, the results showed that temperature and pH did not significantly affect the diversity of bacteria. Cherry juice had the highest number of Colony Forming Units while passion fruit juice had the lowest. In total seven (7) species of bacteria were found including E.coli, S. aureus, Lactobacillus sp, Acetobacter sp, Bacillus subtilis, Bacillus cereus, and Micrococcus. The results for the Colony Forming Units were found to be above maximum acceptable levels for fruit juices. The results of this study demonstrate that unpasteurised juices may be a threat to public health and hazardous to humans if not processed in a sanitary manner.

Unlocking Nature’s Secret: Microbiological and Nutrient Profiling of Fermented Apple

Aim: This study aimed to investigate the microbiological and nutrient composition of naturally fermented apple cider. 
 Place and Study Duration: Department of Microbiology, between June and August 2023.
 Methodology: The purchased apples were weighed, cut into dice, cleaned, and incorporated into distilled water. Subsequently, they were allowed to ferment spontaneously at room temperature in a 500 mL conical flask. The sample was inoculated onto sterilized glucose yeast carbonate agar and subsequently incubated at 30°C for 48 hours. The colony characteristics of the isolates on glucose yeast carbonate agar were observed. Gram’s staining and other standard biochemical tests were performed to identify the isolates. During the fermentation period, the pH of the sample was determined. The proximate content (moisture, protein, crude fat, and carbohydrate) of the apple cider was also analyzed.
 Results: Microscopy revealed the isolates to be Gram-negative bacteria with rod-shaped morphology. The growth characteristics of the isolates on selective media and the results of biochemical tests suggested the presence of Acetobacter sp. The pH of the sample tends towards 4.0, suggesting the production of acidic compound. The apple cider produced had a high moisture content (78.04%), and the protein content was 20.04%. The results showed low concentrations of ash content (0.49%), carbohydrate (0.44%), and lipid (0.99%).
 Conclusion: The presence of macro and micronutrients in apple cider has been associated with some positive health effects, which are enhanced through fermentation, making them a valuable option for health-conscious consumers.

Optimization, Characterization, and Cytotoxic Study of Bio Cellulose by Acetobacter sp Strains to Engender Biodegradable Food Wrapper

Acetic acid bacteria synthesized microbial cellulose were isolated from various citrus fruits, enabled by increased cellulose production to develop a biodegradable polymer as a food wrapper. The objective of the research cynosures on the isolation, enrichment, identification, and optimization of bacteria that produce cellulose, characterization, and cytotoxic study of the obtained cellulose. Two highly effective cellulose producers, Acetobacter lovaniensis (A1) and Acetobacter fabarum (A2), were isolated based on their morphology, biochemical analysis, and 16s rRNA sequencing. Studies were conducted to optimize pH, temperature, inoculum size, nitrogen, and carbon sources. Strain A1 produced 0.715 g/100 ml, whereas A2 produced 0.856 g/100 ml of cellulose under optimum growth conditions. The characteristics of microbial cellulose were examined using scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). A cytotoxicity study for the obtained cellulose has been conducted with mouse embryo fibroblast cells (3T3-L1) and showed 97% viability of cells with the lowest concentration of 12.5 µg/ml. These isolates could be employed in fermentation technology to produce cellulose polymer-based sustainable biodegradable food wrappers.

Effects of resveratrol on the cell membrane and intracellular Biomacromolecules of Acetobacter sp.

The bacteriostatic mechanism of resveratrol (RES) on Acetobacter sp. based on the cell membrane, intracellular enzymes and DNA was studied. Our results showed that the minimum inhibition concentration (MIC) of RES was 2 mg/mL, and the growth curve confirmed its better bacteriostatic activity against Acetobacter sp. The content of unsaturated fatty acids (UFAs) and hydroxyl fatty acids (HFAs) of Acetobacter sp. cell membrane after low-concentration RES treatment increased, while the content of saturated fatty acids (SFAs) and cyclic fatty acids (CFAs) decreased. Furthermore, the cell membrane fatty acid-related genes (fabA, fabG, and cfa) and stress-regulating gene (rpoH) were down-regulated. Moreover, RES not only disrupted the cell morphology and the cell membrane integrity of Acetobacter sp., but also caused oxidative damage to the cell membrane of Acetobacter sp. In addition, RES reduced the activity of alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH), and could bind genomic DNA through a groove pattern, which revealed the inhibitory mechanism of RES against Acetobacter sp. at the molecular level.

Effects of different acetic acid bacteria strains on the bioactive compounds, volatile compounds and antioxidant activity of black tea vinegar

This study intends to produce a black tea vinegar (BTV) from low-quality bulk black tea in order to increase its consumption and added value, and to benefit from its functional characteristics. Three strains (Acetobacter sp. GDMCC1.152, Acetobacter pasteurianus GDMCC1.67, and Acetobacter aceti ATCC15973) of acetic acid bacteria (AAB) were inoculated into black tea infusion (BTI) with ethanol to produce BTV, and their effects on bioactive compounds, antioxidant activity, and volatile compounds in the vinegars were revealed. The results showed that the three strains were suitable for the production of BTV, and the vinegar quality was the best after acetic acid fermentation for 6 days. Compared with BTI, the contents of organic acids and volatile compounds and the antioxidant activity of the vinegars increased significantly. Among them, the vinegar produced by GDMCC1.152 strain had the highest content of organic acids, tea polyphenols (TPs), thearubigins (TRs), theabrownines (TBs), and volatile compounds. It also possessed the strongest antioxidant activity and a rich taste with an apple-like aroma. In summary, AAB fermentation can effectively improve the flavor and quality of BTI and produce a new healthy product with high activity, and Acetobacter sp. GDMCC1.152 is the most suitable strain for the production of BTV.

Asymmetric reduction of 4-trimethylsilyl-3-butyn-2-one to (R)-4-trimethylsilyl-3-butyn-2-ol catalyzed by a novel strain lyophilized Acetobacter sp. CCTCC M209061 in an aqueous/ionic liquid biphasic system

Asymmetric reduction of 4-trimethylsilyl-3-butyn-2-one to (R)-4-trimethylsilyl-3-butyn-2-ol catalyzed by a novel strain lyophilized Acetobacter sp. CCTCC M209061 in an aqueous/ionic liquid biphasic system

Chitooligosaccharides production from shrimp chaff in chitosanase cell surface display system

Chitin refers to a natural biopolymer, which is economically significant to next-generation biorefineries. In this study, a novel high-yield method with cell surface-display chitosanase (CHI-1) was built to produce chitooligosaccharides (COS) from shrimp chaff through the co-fermentation in the presence of Bacillus subtilis and Acetobacter sp. Under the optimized co-fermentation conditions (5 g/L yeast extracts, 10 g/L KH2PO4, 6% ethanol, 50 g/L glucose), the final deproteinization (DP) and demineralization (DM) efficiency and the chitin yield were achieved as 94, 92 and 18%, respectively. The engineered E. coli BL21-pET23b(+)-NICHI maintained 81% of the initial enzyme activity after 40 days at room temperature. The crude CHI-1 was inactivated after one-day interacting with prepared chitosan. Moreover, E. coli BL21-pET23b(+)-NICHI still maintained excellent hydrolysis ability in 7 days, and the COS yield reached 41%. Accordingly, the proposed method exhibited excellent stability and a high hydrolysis efficiency to produce COS with whole engineered cells.

Efficient 3-hydroxypropionic acid production by Acetobacter sp. CIP 58.66 through a feeding strategy based on pH control

Acetic acid bacteria (AAB) can selectively oxidize diols into their corresponding hydroxyacids. Notably, they can convert 1,3-propanediol (1,3-PDO) into 3-hydroxypropionic acid (3-HP), which is a promising building-block. Until now, 3-HP production with AAB is carried out in batch and using resting cells at high cell densities (up to 10 g L−1 of cell dry weight). This approach is likely limited by detrimental accumulation of the intermediate 3-hydroxypropanal (3-HPA). Herein, we investigate an alternative implementation that allows highly efficient 3-HP production with lower cell densities of growing cells and that prevents 3-HPA accumulation. First, growth and 3-HP production of Acetobacter sp. CIP 58.66 were characterized with 1,3-PDO or glycerol as growth substrate. The strain was then implemented in a bioreactor, during a sequential process where it was first cultivated on glycerol, then the precursor 1,3-PDO was continuously supplied at a varying rate, easily controlled by the pH control. Different pH set points were tested (5.0, 4.5, and 4.0). This approach used the natural resistance of acetic acid bacteria to acidic conditions. Surprisingly, when pH was controlled at 5.0, the performances achieved in terms of titer (69.76 g3-HP L−1), mean productivity (2.80 g3-HP L−1 h−1), and molar yield (1.02 mol3-HP mol−11,3-PDO) were comparable to results obtained with genetically improved strains at neutral pH. The present results were obtained with comparatively lower cell densities (from 0.88 to 2.08 g L−1) than previously reported. This feeding strategy could be well-suited for future scale-up, since lower cell densities imply lower process costs and energy needs.

ANALYSIS OF THE BIOLOGICAL PROPERTY OF SOME SYNTHESIZED ORGANOTIN (IV) COMPLEXES OF HEXANEDIOIC ACID

Organotin compounds find a wide range of technological, agricultural, and industrial applications. In this research three organotin (IV) complexes were synthesized of the type Ph3SnL, Ph2SnL2, and Bu2SnL2 with the ligand L; (HOOC(CH2)4COOK). The ligand was prepared by reacting hexanedioic acid with KOH while complexes were synthesized by reacting L with Ph3SnOH, Ph2SnO, and Bu2SnO separately in methanol-propanol solvents. These compounds were tested for antimicrobial activity against two Gram-positive bacteria: Methicillin-Resistant Staphylococcus aureus and Vancomycin-Resistant enterococci, three Gram-negative Bacteria: Salmonella typhi, Pseudomonas aeruginosa and Acetobacter sp and seven fungi strains: Aspergillus nigre, Aspergillus flavus, Monascus ruber, Candida albicans, Microsporum canis, Rhizopus sp, and Fomitopsis pinicola. Three standard drugs: ciprofloxacin, fulcin, and ketoconazole were used at the concentration of 10 μg/mL as control drugs. Results showed that compounds synthesized in general exhibited significant antimicrobial activity higher than the ligand with inhibition zones ranging from 20 – 33 mm at the minimum inhibition concentration (MIC) and minimum bactericidal and fungicidal concentrations (MBC/MFC) range from 12.50 – 50 μg/mL and 50 – 200 μg/mL, respectively. The order for the antibacterial and antifungal activity in this study was Ph3SnL Ph2SnL2 > Bu2SnL2> L. Organotin moieties play a vital role in deciding the antimicrobial activity of an organotin compound; this is true in this work.

The improvement of white pepper quality through fermentation process by Acetobacter sp

White pepper is a potential plantation commodity. The improvement of white pepper quality has been developed by the fermentation method. This research aimed to study the characteristics of white pepper through fermentation by the addition of Acetobacter sp. The procedures of the study consisted of several stages, i.e handling of raw material, fermentation, decorticating, washing, drying and quality analysis. The raw material was used in this study from Sukabumi, Indonesia. After threshing, 1.2 kg of pepper was soaked in water mixed with inoculum culture. The experiment used a completely randomized design (CRD) with two replications. The treatment consisted of: A) concentration of Acetobacter sp (A1 = 15, A2 = 20, A3 = 25%) and B) soaking duration (B1 = 3, B2 = 5 and B3 = 7 days). The result showed that the best treatment was the fermentation conducted for 5 days with the addition of 25% of Acetobacter sp. This condition produced white pepper in fulfilling in requirement of SNI standards with piperine content of 3.82%, essential oil content of 2.4% and TPC of 1.25 x 102 CFU/g. These cleaner bio-processes could contribute to the production of pepper providing environmentally friendly and sustainable methods.

Description of the temporal dynamics in microbial community composition and beer chemistry in sour beer production via barrel ageing of finished beers

Currently, there is a strong interest in barrel ageing of finished, conventionally fermented beers, as a novel way to produce sour beers with a rich and complex flavour profile. The production process, however, remains largely a process of trial and error, often resulting in profit losses and inconsistency in quality. To improve product quality and consistency, a better understanding of the interactions between microorganisms, wood and maturing beer is needed. The aim of this study was to describe the temporal dynamics in microbial community composition, beer chemistry and sensory characteristics during barrel ageing of three conventionally fermented beers that differed in parameters like alcohol content and bitterness. Beers were matured for 38 weeks in new (two types of wood) and used (one type of wood) oak barrels. Beer samples were taken at the start of the maturation and after 2, 12 and 38 weeks. Microbial community composition, determined using amplicon sequencing of the V4 region of the bacterial 16S rRNA gene and the fungal ITS1 region, beer chemistry and sensory characteristics substantially changed throughout the maturation process. Likewise, total bacterial and fungal population densities generally increased during maturation. PerMANOVA revealed significant differences in the bacterial and fungal community composition of the three beers and across time points, but not between the different wood types. By contrast, significant differences in beer chemistry were found across the different beers, wood types and sampling points. Results also indicated that the outcome of the maturation process likely depends on the initial beer properties. Specifically, results suggested that beer bitterness may restrain the bacterial community composition, thereby having an impact on beer souring. While the bacterial community composition of moderately-hopped beers shifted to a dominance of lactic acid bacteria, the bacterial community of the high-bitterness beer remained fairly constant, with low population densities. Bacterial community composition of the moderate-bitterness beers also resembled those of traditional sours like lambic beers, hosting typical lambic brewing species like Pediococcus damnosus, Lactobacillus brevis and Acetobacter sp. Furthermore, results suggested that alcohol level may have affected the fungal community composition and extraction of wood compounds. More specifically, the concentration of wood compounds like cis-3-methyl-4-octanolide, trans-3-methyl-4-octanolide, eugenol and total polyphenols was higher in beers with a high alcohol content. Altogether, our results provide novel insights into the barrel ageing process of beer, and may pave the way for a new generation of sour beers.

Characteristics of Dry Starters of Indigenous Cocoa Aceh Bacteria Isolate

This research aims to study dry starter manufacture of isolates Lactic acid bacteria (LAB), Acetic acid bacteria (BAA) and mixture of LAB and AAB isolates for Aceh cocoa fermentation. This research is an exploratory laboratory with 3 stages: the rejuvenation of bacteria, bacterial isolates characterization and manufacture of dry starter. The analysis carried out by analysis of moisture content, cell viability and descriptive organoleptics (flavor, color and texture). The results reveal that the five of isolates BAL and BAAL. sake, L. carnis, L. coryniformis, Gluconobacter sp dan Acetobacter sp) can be rejuvenated well. L. coryniformis and Gluconobacter sp is selected bacteria (potential) that has the ability to degrade protein and pectin. The resulting dried starter had an average water content 9.77% and cell viability 1,3 x 105CFU/g. Organoleptic characteristics of dried starter as a whole has a sour flavor, bright color and smooth texture. The best treatment was obtained by the treatment using selected LAB isolate (L. coryniformis) with the highest cell viability was 1,9 x 107 CFU/g.

A Modified, Efficient and Sensitive pH Indicator Dye Method for the Screening of Acid-Producing Acetobacter Strains Having Potential Application in Bio-Cellulose Production.

It is imperative that promising bacterial cellulose-producing bacteria mainly belongs to genera Acetobacter (acid-producing bacteria). In order to screen cellulose-producing Acetobacter, the isolated cultures from vinegar/rotten fruits were inoculated in Hestrin-Schramm (HS) medium containing ethanol and CaCO3. After the desired incubation, the positive cultures form a zone, which is observed around the bacterial growth, resulted from the solubilization of CaCO3 by acetic acid produced from the oxidation of ethanol during fermentation. However, in this method, the clarity of the solubilized zone is not very sharp and distinct. In the present, investigation, an improved method for screening, of the microorganisms producing acetic acid has been developed. In this method, methyl red (MR) is incorporated as a pH indicator in HS medium containing ethanol and CaCO3. Plates containing MR at alkaline pH are yellow and turn dark red at acidic pH. Thus, a distinctive, clear zone is formed around bacterial colonies producing acetic acid and is easy to differentiate between acid producers and non-producers. The present method is more rapid, accurate, and sensitive and can be successfully be used for the detection of acetic acid-producing bacteria particularly for the screening of potent cellulose producer Acetobacter sp.

A hazard to human health - pesticide residues in some vegetal and animal foodstuff

Highly efficient asymmetric reduction of 2-octanone to (R)-2-octanol catalyzed by immobilized Acetobacter sp. CCTCC M209061 cells was achieved in a biphasic system. Bioreduction conducted in aqueous single phase buffer was limited due to poor solubility and toxicity towards cells cause by product accumulation. Introduction of [C4MIM]·Ac accelerated the biotransformation process, giving 99% yield, >99% product e.e. and 1.42-fold higher initial reaction rate in conversion of 10 mM 2-octanone as substrate, compared with 99% yield, 97.3% product e.e. and 1.57 μmol min−1 of initial reaction rate in a aqueous single phase buffer system containing 6 mM 2-octanone as the optimal substrate concentration. Moreover, in the [C4MIM]·Ac-containing buffer/n-tetradecane biphasic system, the optimal substrate concentration was enhanced by 83 times (500 mM) in comparison with that in aqueous single phase buffer, resulting in 53.4% yield (267 mM), 99% product e.e. with 8.9 mM g-1 h-1 space time yield.

Characterization and Biological Activities of an Alkali Soluble Exopolysaccharide from Acetobacter

Natural polysaccharides have received much attention due to the plethora of their applications. Acetobacter sp. MRL 5A (KX082688) produced an alkali soluble exopolysaccharide (20.39 g/L) on sucrose based media during the late log and early stationary phases. The exopolysaccharide was insoluble in water with high moisture-retention ability and produced viscous solutions and gels. The exopolysaccharide contained 40.3% glucose, 34.4% galactose, 22.2% mannose and 3.1% of arabinose monomers revealed by GC. The exopolysaccharide showed emulsifying, flocculating and in-vitro antioxidant activity similar to standard exopolysaccharides like dextran and xanthan. This EPS can be of potential use in food, cosmetic, pharmaceutical and biomedical fields.

Significantly enhancing the biocatalytic synthesis of chiral alcohols by semi-rationally engineering an anti-Prelog carbonyl reductase from Acetobacter sp. CCTCC M209061

Chiral alcohols and their derivatives are vital building blocks to synthesize pharmaceutical drugs and high-valued chemicals. Wild-type carbonyl reductase AcCR from Acetobacter sp. has ideal enantioselectivity toward 11 prochiral substrates (e.e.>99%) but poor activity. In this work, a semi-rational engineering was performed to enhance the activity of AcCR. Fortunately, three positive double-mutants (mut-E144A/G152 L, mut-G152 L/Y189 N, and mut-I147 V/G152 L) with specific activity 17–61 folds higher than that of enzyme without modified were achieved. Kinetic studies suggested that the catalytic efficiencies (kcat/Km) of these mutants were also well enhanced. Finally, these modified mut-AcCRs were successfully applied in asymmetric reductions of 11 structurally diverse prochiral substrates (200 mM) with excellent product yields (76.8%–99.1%) and enantiomeric excess (e.e.>99%), which provides an alternative strategy for efficient synthesis of chiral alcohols for pharmaceuticals industry with ideal yield and enantioselectivity.

Antioxidant activity of biocellulose-based films incorporated with powder of soursop leaves (Annona muricata L)

Biocelluloses are natural materials that are produced from Acetobacter sp through fermentation in coconut water as the medium. In this study, biocellulose-based edible film was used as the carrier film for the antioxidant agents (the soursop leave powder (Annona muricata L)). This leave is considered as a good source of natural antioxidant, while all parts of the fruit are used in traditional medicine. This work aimed to evaluate the antioxidant activity of biocellulose-based edible film added with soursop leave powder. The biocellulose was formed in slurry and leaves of fruit was crushed into powder. The edible films were prepared by mixing biocellulose slurry, carboxy methyl cellulose (CMC) as the homogenizer, and the leaves powder, casting, and drying in the oven at 40 °C for 24 h. The IC50 of methanol extract of leaves powder and edible film containing 0.2 g leaves powder were 89.89 mg/mL and 363.26 mg/mL, respectively. All methanol extracts of edible films incorporated with soursop leaves powder inhibited DPPH about 71.10-86.80% and they remained above 70% after storage in a plastic bag at room temperature for one month. The edible films also had the thickness of 0.040-0.067 mm, the solubility of 80.30-90.20% and all compounds of edible films were still available based on SEM and FTIR results.

Highly efficient asymmetric reduction of 2-octanone in biphasic system by immobilized Acetobacter sp. CCTCC M209061 cells

Highly efficient asymmetric reduction of 2-octanone to (R)-2-octanol catalyzed by immobilized Acetobacter sp. CCTCC M209061 cells was achieved in a biphasic system. Bioreduction conducted in aqueous single phase buffer was limited due to poor solubility and toxicity towards cells cause by product accumulation. Introduction of [C4MIM]·Ac accelerated the biotransformation process, giving 99% yield, >99% product e.e. and 1.42-fold higher initial reaction rate in conversion of 10 mM 2-octanone as substrate, compared with 99% yield, 97.3% product e.e. and 1.57 μmol min−1 of initial reaction rate in a aqueous single phase buffer system containing 6 mM 2-octanone as the optimal substrate concentration. Moreover, in the [C4MIM]·Ac-containing buffer/n-tetradecane biphasic system, the optimal substrate concentration was enhanced by 83 times (500 mM) in comparison with that in aqueous single phase buffer, resulting in 53.4% yield (267 mM), 99% product e.e. with 8.9 mM g-1 h-1 space time yield.

Bioleaching of Major, Rare Earth, and Radioactive Elements from Red Mud by using Indigenous Chemoheterotrophic Bacterium Acetobacter sp.

The aim was to study the bioleaching performance of chemoheterotrophic bacterium involved in leaching of major, rare earth, and radioactive elements from red mud (RM), and to explore the underlying mechanism. An acid-producing bacterium, identified as Acetobacter sp., was isolated from RM impoundment and used in the bioleaching experiments under one-step, two-step and spent medium process at up to 10% pulp density. The results showed that the leaching ratios of Al, Lu, Y, Sc, and Th were 55%, 53%, 61%, 52%, and 53% respectively under one-step process at 2% pulp density. Under both one- and two-step processes at 2% pulp density, the radioactivity of bioleached RM can meet the relevant regulation in China. The total amount of organic acids excreted by Acetobacter sp. increased with an increase of RM pulp density. After bioleaching, contents of hematite and gibbsite decreased but perovskite increased in RM. Micromorphology analysis indicated that the cells of Acetobacter sp. adhered to RM particles and formed large-size aggregates, and a new crystal of weddellite emerged. In view of the shorter lag phase and smaller biomass comparing to fungi even under direct contact with RM, bacterium Acetobacter sp. is supposed to apply to in situ heap or dump bioleaching of RM.