Isolates A1 Research Articles

Isolation, Characterization and Activity Test of Soil Origin Bacteria Amilage

This study aimed to obtain amylase-producing potent bacteria from soil and test the amylase activity produced. Soil samples were taken from the Biological Education and Research Forest, Andalas University. The isolation was done by using the stratified dilution technique on agar media. The screening of amylase activity employed the qualitative and quantitative tests on agar starch. From 8 isolated amylolytic bacteria, there were three isolates with amylolytic potential. The results of characterization and identification based on Bergey's Manual of Determinative Bacteriology show that isolates A4, A1, and A6 belonged to the genus Bacillus, Corynebacterium, and Klebsiella. The bacteria obtained can then be produced and optimized for the needs of industrial enzymes.

Isolation of Bacillus spp. from rhizosphere of garden soil: their potential role in amylase production and nitrogen cycle

Rhizobacteria influence plant growth by producing various substances like enzymes and play role in nitrogen cycle. Microbes are the most important sources of enzymes because of their stability and reduced price in production. In our present investigation, soil samples were collected from rhizosphere of garden soil and a total of eight isolates of Bacillus spp. were presumptively identified by morphological, cultural and biochemical analysis with the conventional technique. The isolates were named as A1, A3, A4, A5, B2, C1, D1 and D2. Amylase enzyme assay was performed by 3, 5-dinitrosalicylic acid method. The highest enzyme activity was observed with the isolate A4 (2.71 U/ml) followed by isolates D2 (2.54 U/ml) and D1 (2.52 U/ml). The highest ammonification was found to be positive with the isolates A4 and B2 followed by isolate D1. Denitrification potential was found to be highest with isolates A4 and A5. No isolates were found to fix atmospheric nitrogen in Jensen’s media after two weeks of incubation. The isolates have a great potential of amylase production and they can be used in different industries as well as in starch rich waste degradation. Involvement of these bacteria in nitrogen cycle may help promote growth of plants.
 Stamford Journal of Microbiology, Vol.10 (1) 2020: 12-15

Screening of antagonistic potential bacteria from rhizosphere soil against phytopathogenic fungi related to selected vegetable crops

Fungal phytopathogens cause serious losses of crop production worldwide, which causes serious losses of crop production. Bacteria play a role as the biocontrol agents for plant disease control. For this reason, the present study was conducted to determine the antagonistic potential of rhizosphere soil bacteria against selected phytopathogenic fungi. The screenings of potential antagonist isolated bacteria were applied by the dual culture technique with fungi Fusarium oxysporum and Colletotrichum melongenae. Molecular characterization was performed through 16S rDNA sequencing analysis. Sixteen (16) out of fifty (50) isolated bacteria showed different degrees of antagonism (25-67%) against both fungi F. oxysporum and C. melongenae. Among them, four (4) isolated bacteria (isolates A4, C1, C2, and E2) exhibited strong antagonism (more than 50% mycelial growth inhibition) against both fungi. The 16S rDNA sequences of the isolated bacteria A4, C1, C2 and E2 were 99-100% similar to Providencia sp. TT14, Bacillus subtilis 168, Bacillus subtilis RKP-2, and Bacillus amyloliquefaciens IBSDG-11, respectively. Based on the capability for the control of mycelial growth against both fungi, B. subtilis IUBTC2 was selected for optimization of growth characteristics and identification the bioactive metabolites which can enhance plant growth and disease control capacity of plants against the phytopathogenic fungi.

Phylogenetic characterization and screening of halophilic bacteria from Algerian salt lake for the production of biosurfactant and enzymes

Environments containing significant concentration of NaCl such as salt lakes harbor extremophiles microorganisms which have a great biotechnology interest. To explore the diversity of Bacteria in Chott Tinsilt (Algeria), an isolation program was performed. Water samples were collected from the saltern during the pre-salt harvesting phase. This Chott is high in salt (22.47% (w/v). Seven halophiles Bacteria were selected for further characterization. The isolated strains were able to grow optimally in media with 10–25% (w/v) total salts. Molecular identification of the isolates was performed by sequencing the 16S rRNA gene. It showed that these cultured isolates included members belonging to the Halomonas, Staphylococcus, Salinivibrio, Planococcus and Halobacillus genera with less than 98% of similarity with their closest phylogenetic relative. The halophilic bacterial isolates were also characterized for the production of biosurfactant and industrially important enzymes. Most isolates produced hydrolases and biosurfactants at high salt concentration. In fact, this is the first report on bacterial strains (A4 and B4) which were a good biosurfactant and coagulase producer at 20% and 25% ((w/v)) NaCl. In addition, the biosurfactant produced by the strain B4 at high salinity (25%) was also stable at high temperature (30-100°C) and high alkalinity (pH 11).

The UV light effects on pectinase production of Pantoea sp. bacteria

The highest pectinase producing isolate A3 out of forty isolates of Pantoea sp. bacteria was subjected to physical effects by using UV light to change in their ability for producing of pectinase, the results appeared increasing their activity and production in some of the mutants more than wild type bacteria, the increase was ranged between 14 to 20% in specific activity between bacterial mutants compared with wild type bacteria. Also, the two highest enzyme-producing isolates were tested for their susceptibility against a group of antibiotics (Rifampin 50mcg, Imipenem 10mcg, Vancomycin 30mcg, Amoxicillin 25mcg, Chloramphenicol 30mcg, Trimethoprim 5mcg, Nitrofurantoin 100mcg, Nalidixic acid 30mcg), results appeared different susceptibilities ranged between resist for amoxicillin,and Nalidixic acid, and sensitive for other antibiotics. The susceptibilities of studied bacteria to some antibiotics were different between resist and sensitive, which considered an indicator of dangerous to human life. The study was aimed to increase the ability of these isolate in producing this enzyme which plays an essential role in different industries in food, cosmetics manufacturing and scientific research, besides, their ability in resisting some of the common antibiotics to confirm the transferring of genetic materials between bacteria that isolated from soil samples, which is considered crucial in the microbial genetics. The study appeared there were apparent effects on the genes that responsible for enzyme production either for increase or decrease their activity and creation of an enzyme, which belong to using physical effects to improvement these feature in bacteria.

Bacillus mycoides A1 and Bacillus tequilensis A3 inhibit the growth of a member of the phytopathogen Colletotrichum gloeosporioides species complex in avocado.

Avocado is affected by Colletotrichum gloeosporioides causing anthracnose. Antagonistic microorganisms against C. gloeosporioides represent an alternative for biological control. Accordingly, in the present study, we focused on the isolation and characterization of potential antagonist bacteria against a member of the C. gloeosporioides species complex with respect to their possible future application. Samples of avocado rhizospheric soil were aquired from an orchard located in Ocuituco, Morelos, Mexico, aiming to obtain bacterial isolates with potential antifungal activity. From the soil samples, 136 bacteria were isolated and they were then challenged against a member of the C. gloeosporioides species complex; only three bacterial isolates A1, A2 and A3 significantly diminished mycelial fungal growth by 75%, 70% and 60%, respectively. Two of these isolates were identified by 16S rRNA as Bacillus mycoides (A1 and A2) and the third was identified as Bacillus tequilensis (A3). Bacillus mycoides bacterial cell-free supernatant reduced the mycelial growth of a member of the C. gloeosporioides species complex isolated from avocado by 65%, whereas Bacillus tequilensis A3 supernatant did so by 25% after 3 days post inoculation. Bacillus tequilensis mycoides A1 was a producer of proteases, indolacetic acid and siderophores. Preventive treatment using a cell-free supernatant of B. mycoides A1 diminished the severity of anthracnose disease (41.9%) on avocado fruit. These results reveal the possibility of using B. mycoides A1 as a potential biological control agent. © 2020 Society of Chemical Industry.

AKTIVITAS ANTIMIKROBA BAKTERI ASAM LAKTAT DARI AIR SUSU IBU (ASI) TERHADAP Listeria monocytogenes FNCC 0156

The aim of the research was to find the potency of Lactic Acid Bacteria isolated from breast milk on inhibiting Listeria monocytogenes FNCC 0156 and to find the magnitude of lactic acid bacteria from breast milk in inhibiting L. monocytogenes FNCC 0156. This reseach consists of two phase: antimicrobial activity of lactic acid bacteria from breast milk and activity of bacteriocin against L. monocytogenes FNCC 0156. Isolate used in this research was A1, A3, A6, A8, A9, B3, B7, B8, and B10b. Antimicrobial activity of lactic acid bacteria from breast milk against L. monocytogenes FNCC 0156 was performed cell free supernatant, cell free neutral supernatant, and cell free neutral heated supernatant. The test was performed by well-agar diffusion method and contact method. The activity of bacteriocin was carried out according to the optimum incubation time of bacteriocin production in cell free heated neutral supernatant. The highest antimicrobial activity was supernatant treatment by well-agar diffusion method and contact method showed by isolate A1 with inhibition diameter of 10.60 mm and a decrease of 1.66 log cycle. The highest antimicrobial activity was neutral supernatant treatment by well-agar diffusion method and contact method showed by isolate B8 with inhibition diameter of 5.11 mm and increased only by 0.18 log cycle. The highest antimicrobial activity on the heated neutral supernatant treatment by well-agar diffusion method and contact method showed by isolate A6 with inhibition diameter of 0.85 mm and a decrease of 0.48 log cycle. The two isolates of cell free neutral heated supernatant treatment was isolate A6 and isolate B8 suspected to have bacteriocin compounds was then continued with isolation of bacteriocin. The result of the second phase showed that optimum time for bacteriocin production of isolate A6 was 36 hours and B8 was 60 hours. The highest antimicrobial activity of bacteriocin was showen by isolate A6 with an average inhibition diameter of 5.36 mm, followed by B8 with an average inhibition diameter of 2.44 mm.
 Keywords: lactic acid bacteria, breast milk, Listeria monocytogenes FNCC 0156, antimicrobial activity, bacteriocin

Isolation and Characterization of Streptomycetes with Potential to Decompose Organic Compounds During Bioremediation of Arable Soil

The study has an objective of isolating and characterizing suspected Streptomycetes with the potential to decompose organic compounds in arable soil. The isolates were grown on a culture media and a total of 61 slopes were inoculated and labeled using the following characterization tests: catalase test, gram staining, oxidase test, motility test, and oxidative-fermentative test. After characterization tests, data generated in the laboratory were analyzed and the study showed that isolates A2 (c, e), B2 (c), C1 (b), C2 (a), D1 (e) and D2 (d) were suspected to be Streptomycetes species. Isolates D1 (d) and D2 (b) were suspected to be Escherichia coli while isolates A1 (a), B2 (a, b) and D1 (a) were suspected to be Bacillus species. Isolates A1 (b), C1 (a), D1 (c), D2 (e) were suspected to be Pseudomonas species. Further identification showed that isolates A2 (d) and B1 (b) could be Enterobacter species while isolates A2 (a, b) were suspected to be Klebsiella species. The study tentatively identified Streptomycetes species; Escherichia coli; Bacillus species; Enterobacter species; Pseudomonas species and Klebsiella species. The suspected Streptomycetes identified were considered as potential organic matter decomposers in arable soil.

Antifungal Mechanism of Rhodotorula mucilaginosa and Aureobasidium sp. nov. Isolated from Cerbera manghas L. against the Growth of Destructive Molds in Post Harvested Apples.

Apples often experience postharvest damage due to being attacked by mold organisms. Several groups of molds such as Aspergillus sp., Penicilium expansum, Botrytis cinerea, and Venturia sp. can cause a serious postharvest disease exhibited as watery regions where areas of blue-green tufts of spores develop. Current methods using fungicides to control pathogenic fungi can cause resistance if applied in the long term. An alternative procedure using yeast as a biological agent has been found. The aim of this study is to screen potential yeast, which has the ability to inhibit the growth of Aspergillus brasielensis (isolate A1) and Aspergillus flavus section flavi (isolate A17) isolated from apple fruits. Antagonism test using YMA dual culture medium using in vitro assays and ITS rDNA identification were performed. The result showed that 3 out of 19 yeast isolated from Cerbera manghas L, T1, T3 and T4, demonstrated the potential ability as a biocontrol agent. ITS rDNA identification demonstrated that T1 has a similarity to Rhodotorula mucilaginosa while T3 and T4 were identified as Aureobasidium sp. nov. The 3 isolates exhibited the ability to reduce the growth of A. brasiliensis sensu lato better than dithane 0.3% with a Disease Incidence (DI) of 100% and a Disease Severity (DS) value of 45%. Only isolate T1 and T3 were able to reduce decay symptoms in apples inoculated with A. flavus sensu lato (with DO and DS were 100% and 25%, respectively) compared to dithane pesticides 0.3%. This study indicated that competition between nutrients occurs between pathogenic molds and under-yeast in vitro and in vivo conditions. However, further studies in the future might be able to elucidate the 'killer' activity and interaction with the pathogen cells and the bio-product production using Rhodotorula mucilaginosa and Aureoubasidium namibiae strains to control postharvest diseases.

Plant growth promoting potential of Brevibacterium sediminis A6 isolated from the tea rhizosphere of Assam, India

Abstract The Tea rhizosphere microbial community harbor diverse plant growth promoting (PGP) rhizobacteria and are relatively less explored. In our study, we isolated 23 distinct bacterial morphotypes from the tea garden of Assam, India. The isolates were screened for their plant growth promotion (PGP) and antifungal traits against three pathogenic fungi, namely Rhizoctonia solani, Corticium rolfsii, and Fomes lamaensis. Out of 23 isolates, 7 isolates showed potential in antifungal activities, amongst which, isolate A6 was found to have promising PGP and antifungal traits. Isolate A6 also exhibited biosurfactant production abilities in the presence of 2% dextrose as a carbon source. Biochemical and molecular characterization revealed its identity as Brevibacterium sediminis. Further quantification assay showed the amount of indole acetic acid (IAA) production (72.51 ± 2.18 μg/mL) and phosphate solubilization (60.644 ± 3.098 μg/mL) by the isolate A6. The PGP activity of the isolate was validated by in vitro trials on rice seedlings. A6 treated seedlings showed a significantly higher root length (p = 0.0350), shoot length (p

Antibacterial activity tests of isolate endophytic bacteria from the tea plant (Camellia sinensis) againts Staphylococcus aureus and Staphylococcus epidermidis

Staphylococcus is one of the most common types of bacteria in Asia that causes local infectious diseases of the skin, nose, urethra, vagina, digestive tract, pneumonia, endocarditis, septic arthritis, and septicemia. Staphylococcus aureus and Staphylococcus epidermidis are the most common types of Staphylococcus in Asia. Tea plants contain bioactive compounds and endophytic bacteria which are widely used as antimicrobial agents. Endophytic bacteria are bacteria that exist in plant tissues, not pathogenic, and have the ability as the host plant. The purpose of this study was to determine the antibacterial activity of endophytic bacterial isolates of tea plants (Camellia sinensis) against the growth of Staphylococcus aureus and Staphylococcus epidermidis bacteria. The antibacterial activity test of endophytic bacteria of tea plants includes a series of processes such as sample selection, surface sterilization of samples, isolation of endophytic bacteria in agar medium, screening, suspension of endophytic bacteria in 0.9 % NaCl and standardized with 0.5 McFarland, making endophytic bacterial culture in nutrient broth medium, making endophytic bacterial supernatant and antibacterial activity test with paper disc diffusion method. The result is that there is an antibacterial activity from the endophytic bacterial supernatant isolates B14, B23, and A2 to the growth of Staphylococcus aureus and Staphylococcus epidermidis. The best antibacterial activity was found in endophytic bacterial B14 isolates with inhibition zones of 7.75 mm and 12.5 mm followed by B23 isolates with 7.5 mm and 8.25 mm inhibition zones and A2 isolates with large inhibition zones of 7.42 mm and 8.16 mm. Endophytic bacteria of tea plants showed antibacterial activity against the growth of Staphylococcus aureus and Staphylococcus epidermidis.

Isolation and screening of Azotobacter Spp. for plant growth promoting properties and its survival under different environmental stress conditions

Because of detrimental changes in the soil condition, the substitution of chemical fertilizer is essential. Quite a lot of alternatives are available to improve the soil productivity now a day such as biofertilizers. Plant growth promoting rhizobacterias (PGPR) is being used as efficient biofertilizers known to influence plant growth by direct or indirect methods. Seeking competent PGPR strains with diverse activities, a total of six Azotobacter were isolated from Orissa University of Agriculture and Technology (OUAT) rice field of Odisha. All these test isolates were screened on the basis of morphological and biochemical characteristics. The result reveals that all isolates are gram negative small rods in shape; all were positive for catalase and oxidase but negative for starch and gelatine hydrolysis. Isolates were then screened for their plant growth promoting properties such as production of indoleacetic acid (IAA), nitrate reduction, ammonia (NH3), phosphate solubilization and antifungal activity. All isolates show IAA, nitrate and phosphate solubilization positive. One of the major constraints on agricultural yield is drought and this circumstance is likely to be intensified in the future due to water shortage worldwide. A number of mitigation approaches and alterations are involved to survive drought stress. Plant growth-promoting rhizobacteria (PGPR) could play a major role in decreasing different stress conditions in plants. From an overall study of six isolates A4 isolate shows significant PGPR and drought tolerant properties.

Isolation, characterization, and screening of actinomycetes producing bioactive compounds from Egyptian soil

Background Unsuitable prescription and the inappropriate use of antibiotics have led to the development of antibiotic resistance in many pathogenic bacteria. So, there is a need to screen for alternative sources, such as actinomycetes, a potent antibiotic producer for antimicrobial activity, with the hope of discovering novel strains proficient to produce antibiotics against the resistant bacteria. Materials and methods In the current work, six actinomycetes were isolated from Egyptian soil, characterized, and then identified by microscopic and macroscopic observations. The bioactive substances were extracted by the solvent extraction method using ethyl acetate. Antimicrobial activity of the obtained extracts was evaluated against some gram-positive and gram-negative bacteria. Fourier-transform infrared spectroscopy analysis and cytotoxic activity of the most active extracts were carried out. Results and conclusion Crude extract of A2 showed 30±0.10-mm mean inhibition zones against gram-positive bacteria Bacillus megaterium. Significantly, the isolate A6 showed the highest mean zone of inhibition of 20.0±0.1, 19.4±0.05, and 19.0±0.10 mm against Pseudomonas aeruginosa, Klebsiella oxytoca, and Escherichia coli, respectively. The isolate A5 only showed the largest antibacterial activity against B. megaterium, with inhibition zone of 69±0.28 mm. Only two isolates (A2 and A6) were chosen for further study based on broad-spectrum activity in comparison with other isolates. The two isolates A2 and A6 were identified as Streptomyces enissocaesilis MT658130 and Streptomyces atrovirens MT658195, respectively, using 16S rRNA. Fourier-transform infrared analysis of the extract of two strains reported the existence of OH, C=C, C-O, S=O, N=C=S, and C-Br as the most efficient groups. Cytotoxic activity of S. enissocaesilis A2 and S. atrovirens A6 extracts against hepatocellular carcinoma (HepG2) cell line showed good cytotoxicity, with 2.97 and 1.48 µg/ml IC50 value, respectively. The results evoked that actinomycete isolates under study have potent biological activities.

Screening of biodegradation potential for n-alkanes and polycyclic aromatic hydrocarbon among isolates from the north-western tip of Pahang

This study has successfully screened for a few selected enzyme activities and hydrocarbon-degrading capability of 18 bacterial isolates from the north-western tip of Pahang. The bacterial isolates were known belong to genus Pseudomonas, Stenotrophomonas, Acinetobacter, Serratia, Bacillus and Exiguobacterium. Among them there are more than 80% were lactase and amylase producers, while only 44% were protease and lipase producers. Gravimetric analysis was performed to test the capa- bility of degrading n-alkanes and polycyclic aromatic hydrocarbons (PAHs). A statistical analysis, Statistical Package for the Social Sciences (SPSS) was used for hydrocarbon utilization analysis. The overall degradation of n-alkanes was revealed to be not significant. On the other hand, based on the statistical analysis PAHs utilization was significant. Isolate A3i was chosen as the best utilizer of n-alkanes, while isolate A2 was chosen for the best PAHs degrader.

Morphological and Molecular Characteristics of Pratylenchus coffeae from the Origin of Robusta Coffee Plantation in Malang, East Java

Pratylenchus coffeae is the most important plant-parasitic nematode in Robusta coffee plantations. Information regarding morphology, morphometric and molecular characters of P. coffeae has not been reported in Indonesia. This study is aimed to describe those characters of P. coffeae that attack Robusta coffee. Root samples were taken from Robusta coffee plantation in Malang, East Java. Nematode extractions was conducted using a mist chamber method. Morphology and morphometric characters were observed from the permanent nematode slides. Single nematode DNA extract was amplified at the D2D3 segment of 28S rRNA and ITS1-5.8S-ITS2 rRNA with universal primers. Amplicon was sequenced and analysed for phylogenetic tree relationships. Female morphological key character of P. coffeae observed are: lip with two annulations, four lateral lines, esophageal overlap with intestine ventrally, monodelphic, and truncated tail shape. Male spicules curved ventrally. Female morphometrics are: n=26, L = 556.4 μm, DGO = 2.4 μm, anterior gonad = 174.8 μm, a = 28.5, b = 6.1, b’ = 4.1, c = 20.1, c’ = 2.3, V = 81.7. A Male is smaller than a female with n=24, L = 505.9 μm, a = 32.3, b = 5.5, b '= 3.9, c = 15.3, c' = 2.8 and T = 40.6. The molecular characters of P. coffeae were investigated for two isolates, namely SA1 and SA2. Based on the D2D3 and ITS1-5.8S-ITS2 regions, isolate SA1 has similarity level of 99% and 97% to the P. coffeae from NCBI. Similar result was shown by Isolate SA2 with similarity of 100% and 100% respectively. Phylogenetic tree analysis using Maximum Likelihood at the D2D3 segment of 28S rRNA and ITS1-5.8S-ITS2 regions showed that P. coffeae in this study was included in one clade with P. coffeae from several countries.

Isolation and Molecular Identification of Biosurfactant Producing Soil Bacteria

Biosurfactants are amphiphilic compound, having hydrophilic and hydrophobic moieties enabling them to reduce surface and interfacial tension at the surface. Their unique properties are applied in various industries such as foaming and wetting agents, emulsifiers, detergents and bioremediation. A total of 98 isolates showed biosurfactant activity using hemolytic activity, drop collapse test and oil spreading assay. All isolates were rod-shaped, Gram positive and majority of them were non-endospore former. Only the isolates showing the highest percentage of emulsification index (E24) and ability to reduce tension were used for species identification using 16S rDNA gene sequencing which were isolates A1(6) and A2(1). Both isolates were identified as Bacillus sp. cp-h50 and Bacillus sp. XT-24 respectively, rod-shaped, endospore former and Gram positive. The biosurfactant produced by both species showed high emulsification index (E24) (A1(6), 63.3% and A2(1), 46.7%) and good surfactant capacity. The size of amplified gene of 16S rDNA gene was approximately 1.5 kb. These features provide evidence that both species could be a potential biosurfactant producer with proper optimization for the production of biosurfactant. The biosurfactant produced by both bacterial species were identified as surfactin using Fourier Transform Infrared Spectroscopy (FTIR).

Effect of Cultural Conditions on Biosurfactant Production by Candida sp. Isolated from the Sap of Elaeis guineensis

Aims: This study is aimed at determining the effect of cultural condition on biosurfactant production by Candida sp. isolates from saps of Elaeis guineensis.
 Methodology: Chemical analysis of the sap was carried out. Yeast isolates from the sap were screened for biosurfactant production based on emulsification index (E24), emulsification assay, haemolytic assay, oil displacement test, CTAB and tilted glass slide ability. The best biosurfactant-producing yeast isolate was identified based on its phenotypic, microscopic, and biochemical characteristics. The emulsification capacity of the produced biosurfactant on selected oils was studied. Optimum cultural and nutritional requirements (temperature, pH, inoculum concentration, nitrogen sources and carbon sources) for biosurfactant production by the isolate were determined.
 Results: The characteristics of the sap from Elaeis guineensis were reducing sugar (0.51 ± 0.03 mg/ml), alcohol (14.04 ± 0.15%), specific gravity (0.827±0.024), and pH (5.68±0.03). The crude biosurfactant produced displaced a thin film of crude oil on petri dish by 55 mm, and revealed high emulsification index (E24) of 52.5% using Olive oil as substrate compared to E24 of 60.6% by sodium dodecyl sulphate (SDS). Based on colonial, microscopic, and biochemical characteristics, the isolate SA2 was identified as Candida sp. The crude biosurfactant showed varying capacity in emulsifying the different oils that were examined. Optimization data revealed maximum biosurfactant production after 7 days of incubation, inoculum concentration of 10%, at temperature of 20ºC, pH of 2 with cassava peel as substrate.
 Conclusion: The study has demonstrated the capacity of Candida sp. from the sap of Elaeis guineensis to produce biosurfactant utilizing cassava peel as substrate. The use of cassava peel, which represents a low-cost substrate, is important in reducing the cost of biosurfactant production. Moreover, using yeasts from Elaeis guineensis make the production process ecologically friendly.

Solubilisasi Fosfat Anorganik oleh Burkholderia spp. pada Rizosfer Kelapa Sawit (Elaeis guineensis Jacq.) di Tanah Mineral Masam

Nugraha et al, 2019. Solubilization of Inorganic Phospate by Burkholderia spp. Associated with Oil Palm Rhizosphere in Mineral Acid Soil. JSLO 8(1):86-93.Phosphate Solubilizing Bacteria (PSB) play important role by enhancing phosphate availability bounded with Al3+ or Fe3+ in acidic soils to oil palm plants through release the inorganic phosphate by enzyme or organic acids solubilization. The aims of this study were to isolate of PSB from oil palm rhizosphere and to conduct a comparative analysis of the solubility inorganic phosphates source by selected PSB. The ability of 15 selected PSB to grow and solubilize aluminum phosphate (AlPO4) and iron phosphate (FePO4) was examined and identified. The highest phospate solubilising efficiency showed K3.1 isolate with phosphate solubilization index 3.2 on NBRIP media. Quantitative analysis revealed that isolate K3.1 solubilized 53.52 mg/mL phosphate in 5 days after being inoculated in AlPO4 containing liquid medium, isolate A4 solubilized 63.45 mg/mL phosphate in 5 days after being inoculated in FePO4 containing liquid medium accompanied by a decrease in pH of the growth medium. Based on the 16s rRNA gene sequence analysis, isolate K3.1 and A.4 were closely related to Burkholderia arboris and Burkholderia gladioli. This potential isolates can be used in order to make oil palm crops more sustainable especially on marginal soil with low pH and less dependent on inorganic P fertilizers.

Characterization of Antibioticproducing Bacterium Isolated From Anthill Sediment With Activity Against ESKAPE Pathogens

Healthcare institutions have seen an increase in infections caused by antibiotic-resistant ESKAPE pathogens. Current antibiotics have become less potent against pathogenic bacteria due to their overuse and misuse. In recent years, scientists have revisited local environments in search of novel antibioticproducing microbes to address the increasing threat of resistance. One species of bacteria was isolated from anthill sediment in coastal North Carolina. This environment was selected for its abiotic properties, including organic substrates, moisture saturation and aeration. Anthill isolate A2, inhibited various Grampositive and negative ESKAPE pathogens or their surrogates, including Staphylococcus aureus, Klebsiella pneumoniae, and Acinetobacter calcoaceticus, in crossstreak tests. 16S rRNA sequencing identified isolate A2 as Pseudomonas koreensis. Mass spectrometry and small-molecule analysis performed on ethyl-acetate extracts of culture supernatant were used to evaluate bioactivity and identify the probable structure of one potential antimicrobial compound, monolauryl maleate. Discovery of novel antimicrobial compounds to replace overused antibiotics may help reduce the impact of antibiotic-resistant pathogens.

Optimalisasi Fosfat untuk Meningkatkan Pertumbuhan Kerapatan Populasi dan Kemampuan Antagonis Saccharomyces cerevisiae terhadap Fusarium sp.

Saccharomyces cerevisiae is a common yeast used as a fermenter in the home industry. This yeast is able to grow in media like waste materials. One of the waste materials that can be used as a medium of yeast growth is waste of coconut water. The use of coconut water as a medium of yeast propagation has been widely used in some types of yeasts. The intake of nutrients such as phosphate will make the yeast cells begin to grow and work faster. The yeast cell takes phosphate as ATP. Khamir will turn it into a phosphate polymerization form that is often found within the mitochondria of these cells. S. cerevisiae has the ability not only in terms of fermentation but also can perform other functions in the biological control process. The main methods of this study include the growth test of S. cerevisiae with the addition of a phosphate (KH2PO4), S. cerevisiae growth test by aerator method, yeast antagonist test. The results showed that S. cerevisiae was able to grow higher with the addition of phosphate nutrients (0.5% KH2PO4). This yeast has the potential to control Fusarium sp. The percentage of inhibition was isolate A0 (9,67%), A1 (11%), A2 (10,67%), A3 (12%), A4 (13%), and A5 (6%).
 Keywords: Yeast, phosphate nutrient, biological control, Fusarium sp.