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Prickly pear cactus as a raw material for lactic acid production by Lactococcus lactis subsp. Lactis

Milouda TAMINE ; Aicha NANCIB ; Nabil NANCIB ; Joseph BOUDRANT

Malaysian Journal of Microbiology.2018;14(1):16-24.

Aims: In recent years, microbial conversion of renewable raw materials has become an important objective in industrialbiotechnology. Wastes from Opuntia ficus indica (OFI) can be considered as potential renewable raw materials in lacticacid production. In this study, the feasibility of lactic acid production using fruits and cladodes of OFI as carbohydratefeedstock was investigated.Methodology and results: Response surface methodology (RSM) based on central composite design (CCD) was usedto evaluate the effects of fermentation parameters for lactic acid production from OFI fruits by Lactococcus lactis subsp.lactis strain, isolated from Algerian raw camel milk. Acid hydrolysis of the OFI cladodes biomass was performed by diluteH2SO4 pretreatment. Lactic acid production from OFI fruits was analyzed using response surface methodology.Variables such as inoculum age and reducing sugars concentration were found to significantly influence lactic acidproduction. Final lactic acid concentration and productivity attained under optimum fermentation conditions were 32.5g/L and 0.74 g/L.h, respectively. The cladodes of OFI are a potential biomass feedstock for lactic acid production. Themaximum lactic acid and volumetric productivity were 16.85 g/L and 0.65 g/L.h, respectively.Conclusion, significance and impact of study: Wastes from OFI can be a good feedstock for lactic acid production byLactococcus lactis subsp. lactis. The methodology as a whole proved to be quite adequate for the design andoptimization of the process. The experimental results also demonstrated the feasibility of using OFI cladodeshydrolysate as a substrate for lactic acid production.

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Antagonistic activity of Streptomyces thermocarboxydus to Fusarium oxysporum: The cause of leaf rot disease on Aloe Vera (Aloe barbadensis Mill.) in Bali, Indonesia

Retno KAWURI1 ; Dewa Ngurah SUPRAPTA ; Youji NITTA

Malaysian Journal of Microbiology.2018;14(1):10-15.

Aims: Aloe vera (Aloe barbadensis Miller) has been cultured in Bali, Indonesia since 2006. Its cultivation area is 170 haincluding 5 regencies i.e. Buleleng, Karangasem, Bangli, Badung and Gianyar. This study was conducted to isolate andidentify the Streptomyces sp. that potentially can be used to inhibit the growth of F. oxysporum and control the leaf rotdisease on aloe vera with and to study the structural responses of F. oxysporum to the treatment of Streptomycesculture filtrate.Methodology and results: Samples were collected from Serokadan, Kerobokan, and Saba, Bali, Indonesia. The isolateof Streptomyces sp. that resulted in the highest antifungal activity was further observed on its morphological andultrastructure characteristics using SEM and TEM. Identification was done by using 16S rRNA sequencing techniques. Agreenhouse experiment was conducted to evaluate the effectiveness of the filtrate of Streptomyces sp. to control the leafrot disease on aloe vera. The Streptomyces GYRRK was identified to be S. thermocarboxydus and the filtrate inhibitedthe growth of F. oxysporum by damaging cell wall and plasma membrane of macro conidia cell, micro conidia, andhypha. Treatment with the filtrate of S. thermocarboxydus with four sprays (one spray equal to 0.5 mL) over inoculatedleaves of aloe vera reduced the leaf rot disease by 68%.Conclusion, significance and impact of study: This result suggests that filtrate of S. thermocarboxydus potentiallycan be used as an alternative control agent against leaf rot disease on aloe vera in Bali.

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Abiotic stresses induce total phenolic, total flavonoid and antioxidant properties in Malaysian indigenous microalgae and cyanobacterium

Nur Husna AZIM ; Atiqah SUBKI ; Zetty Norhana Balia Yusof

Malaysian Journal of Microbiology.2018;14(1):25-33.

Aims: The use of microalgae as source of natural antioxidants is under explored in Malaysia. Previous studies haveshown that microalgae contain minerals, polysaccharides, amino derivatives, carotenoids and phenolic compounds. Thisstudy aimed to determine total phenolic and flavonoid compounds and antioxidant activity when microalgae(Nannochloropsis oculata and Tetraselmis sp.) and cyanobacterium (Anabaena sp.) were subjected to abiotic stresses.Methodology and results: Treatment of sodium chloride (NaCI), sodium hypochlorite (NaOCI) and copper (Cu2+) weregiven when the cultures reached the exponential phase of growth and were collected at three different time points. Nontreatedcultures were used as controls. Total phenolic and flavonoid contents were determined using Folin-Ciocalteauphenol reagent and aluminium chloride colorimetric assays. Antioxidant activities were measured using 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging activity assay. Tetraselmis sp. exhibited the highest phenolic contentunder copper stress (10.35 ± 0.33 μg GAE/mg extract). Nannochloropsis oculata showed the highest total flavonoidcontent under copper stress (33.85±3.16 μg QE/mg extract). Anabaena sp. showed the highest radical scavengingactivity under NaOCI stress (96.42 ± 0.26%).Conclusion, significance and impact of study: This study showed that total phenolic, flavonoid and antioxidantactivities in treated cultures were high compared to non-treated cultures. These microorganisms could be utilized as asource of useful bioactive compounds while exploiting its abund

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A comparison of ZEN double-quenched probe and SYBR GreenER chemistries in the real-time PCR based quantitative detection of enterotoxigenic Bacillus cereus in milk

Nur Thaqifah SALIHAH ; Mohammad Mosharraf HOSSAIN ; Mas Rina Wati Abdul Hamid ; Minhaz Uddin AHMED

Malaysian Journal of Microbiology.2018;14(1):34-40.

Aims: Comparison between ZEN™ double-quenched probe and SYBR GreenER™ real-time PCR assay to develop asensitive and specific assay for the direct detection and quantification of enterotoxigenic Bacillus cereus in milk.Methodology and results: Novel primers and probe were designed to target the enterotoxigenic nhe gene. Theperformance of ZEN™ double-quenched probe and SYBR GreenER™ chemistry were compared by using knownconcentrations of purified DNA. ZEN™ double-quenched probe showed a dynamic range of 3 log units and sensitivity of600 fg/reaction or 100 copies/reaction. SYBR GreenER™ chemistry had a wider quantitative dynamic range of 6 logunits with sensitivity down to 6 fg/reaction or 1 copy number/reaction. Thus, SYBR GreenER™ chemistry was 100×more sensitive with wider quantification range compared to ZEN™ probe chemistry. Similar result was also found forSYBR GreenER™ assay and ZEN™ probe chemistry in DNA extracted directly from artificially inoculated milk, with thelowest limit of detection by SYBR GreenER™ assay in the range of 6 fg/reaction or 25 copies/mL and it quantifiedBacillus cereus in milk with high relative accuracy.Conclusion: SYBR GreenER™ assay provides a fast, sensitive and specific detection and quantification ofenterotoxigenic Bacillus cereus and allowed a direct assessment and quantification of Bacillus cereus from milk foodsample.Conclusion, significance and impact of study: The study shows an efficient, specific and highly sensitive method ofdirectly assessing the enterotoxigenic Bacillus cereus from milk product, using cheaper dsDNA binding SYBRGreenER™ dye.

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Characterization of two xerophilic Aspergillus spp. from peanuts (Arachis hypogaea)

Nur Amalina KAMARUDIN ; Latiffah ZAKARIA

Malaysian Journal of Microbiology.2018;14(1):41-48.

Aims: Xerophilic Aspergillus spp. promote the growth of toxigenic species. Since mycotoxins are toxic to human andanimal, identification of these species is important.Methodology and results: Two xerophilic species isolated from peanuts (Arachis hypogaea) were identified based onmorphological characteristics, molecular identification, and phylogenetic analysis using internal transcribed spacerregion, β-tubulin, and calmodulin sequences.Conclusion, significance and impact of study: The occurrence of A. chevalieri and A. amstelodami on peanutsprovides favorable growth conditions for less xerophilic Aspergillus as well as other spoilage-related fungal genera,particularly mycotoxin-producing species that could lead to mycotoxin contamination. The occurrence of A. chevalieriand A. amstelodami on peanuts might also reduce shelf life and affect the quality of the kernels. To our knowledge, thisis the first report of the occurrence of A. chevalieri and A. amstelodami on a food product in Malaysia, and the finding ofthis study contributes to the repertoire of Aspergillus species that are associated with food products.

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Antimicrobial activity of Aspergillus sp. IBRL MP15 CCL, an endophytic fungus isolated from Swietenia macrophylla leaf against human pathogens

Chean Ring LEONG ; Adib Arifah Binti Mansur ; Syarifah Abdul RASHID ; Swee Ngim ANG ; Wen-Nee TAN ; Woei Yenn TONG ; Darah IBRAHIM

Malaysian Journal of Microbiology.2018;14(1):49-54.

Aims: Endophytes are microorganisms residing in the living tissues of the host plant and may contribute to their hostplant by producing a plethora of bioactive compounds that provide survival value to the plant. This study aimed toevaluate the antimicrobial activity of Aspergillus sp. IBRL MP15 CCL, an endophytic fungus isolated from Swieteniamacrophylla leaf.Methodology and results: The antimicrobial activity was evaluated with disc diffusion and a colorimetric brothmicrodilution test against 15 organisms comprising of 4 Gram-positive bacteria and 4 Gram-negative bacteria, 4 fungiand 3 yeast. On disc diffusion assay, the fungal extract was shown to inhibit the growth of 7 test bacteria and 3 testyeast. The antibacterial activity was more pronounced with extract from fungal culture with host plant extractsupplementation with significantly larger inhibition zones on all susceptible test microorganisms. The minimal inhibitoryconcentration of the extract ranged from 250 to 4000 μg/mL indicating different level of susceptibility of the testedpathogens against the fungal extract. The killing kinetic study shows that antimicrobial activity of the fungal extract isconcentration dependent and it can act as bactericidal at higher concentration.Conclusion, significance and impact of study: The findings of this study suggest that Aspergillus sp. IBRL MP15CCL can be a promising source of antimicrobial agent to be further studied and developed

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Degradation of caffeine by Pseudomonas monteilii KRM9

Sattya ARIMURTI ; Tri ARDYATI ; Yulia NURANI ; Tri Agus SISWOYO ; Suharjono SUHARJONO

Malaysian Journal of Microbiology.2018;14(1):55-60.

Aims: The objective of this research was to isolate caffeine-degrading bacteria from coffee pulp waste in Indonesia andcharacterize their caffeine degradation activity.Methodology and results: The caffeine-degrading bacteria were isolated from coffee pulp wastes of Coffea arabicaand C. canephora. These isolates were selected based on their caffeine degradation activity. The identification andbiochemical properties of the best isolate were conducted via 16S rDNA sequence analyses and by using the Microbactkit. Meanwhile, caffeine degradation activity of this bacteria was analyzed by using LC-MS/MS. The results indicatedthat fourteen bacterial isolates were able to degrade caffeine. The highest caffeine degradation activity was performedby isolate KRM9 at the rate of 99.26 ± 0.01%, on a caffeine medium after 24 h of incubation. Based on the 16S rDNAanalyses, the KRM9 isolate was identified as Pseudomonas monteilii. Till present, this species has not been reported asa caffeine-degrading bacterium. However, LC-MS/MS analysis indicated that caffeine was degraded by P. monteiliiKRM9 and theobromine was not the secondary metabolite of caffeine degradation.Conclusion, significance and impact of study: Pseudomonas monteilii KRM9 was detected as a new isolate ofcaffeine-degrading bacteria. This bacterium can be introduced as an agent to degrade caffeine from coffee pulp waste. Itis expected that further research can be conducted on the overall mechanism of caffeine degradation by P. monteiliiKRM9

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Shades of fungi – A review of pigments from endophytic fungi

Angelica Fiona TAN ; Lew Yao LONG ; Kavindi NAGAHAWATTE ; Moritz MÜ ; LLER

Malaysian Journal of Microbiology.2018;14(1):70-79.

Endophytic fungi are a unique group in the Fungi kingdom as they spend the majority of their life cycles within the livingtissue of the host organism without causing apparent harm. The endophyte-host relationship is typically commensalismor mutualistic, with pathogenicity an issue only when either party is under stressed. The contribution of endophytic fungito the host is mostly in the form of chemical protection – secondary metabolites with bioactivities against invadingorganisms which may harm the host and consequentially threaten the survival of the endophyte. Many of these chemicalcompounds have been found to be pigments. Due to easy visual identification, many pigments from fungal sources havebeen isolated and characterised. This review highlights the potential of endophytic fungi as a source of pigments; withadditional focus on significant bioactivity, major chemical classes and biosynthesis. Existing and potential commercialapplications of natural pigments by endophytes are also discussed.

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Estimation of growth in solid state fermentation: A review

Musaalbakri Abdul MANAN ; Colin WEBB

Malaysian Journal of Microbiology.2018;14(1):61-69.

Carleysmith and Fox (1984) stated “without doubt, the single most vital yet most problematical value sought duringfermentation is biomass estimation”. Achieving a positive result in determining biomass remains a major challenge insolid state fermentation (SSF). Fungi are well-characterised microorganisms and are widely used in SSF due to theirability to colonise and penetrate into the solid substrate. The compressed structure of the mycelia and the solid substratedoes not allow a complete recovery of the biomass, which may not be insurmountable. Since the use of a directtechnique such as the dry weight method is impractical, the use of an indirect estimation technique is the only alternative.This review examines strategies that have been used to estimate biomass in SSF. Many promising indirect estimationtechniques are available, which can be classified into six categories as follows; (i) measuring cell components notpresent in the substrate; (ii) measuring biomass component present in both substrate and biomass; (iii) measuring othersecondary metabolites; (iv) measuring metabolic activity; (v) measuring images from direct microscopic observation and(vi) measuring biomass from the substrate matrix. New potential technique and future directions are also discussed inthis review. Although significant advances have been made with the availability of various techniques; however, progresshas been very unsatisfactory. The evaluation of microbial growth in SSF may sometimes become laborious, impracticaland inaccurate. Essentially, this remains another critical issue for monitoring growth. The information of the profile offungal biomass growth throughout any SSF process constitutes an essential parameter in estimation of kinetic variablesand subsequently, scale-up of the process.

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Proximate and biochemical analysis for marine and freshwater algae

Soopna PUSPANADAN ; Wan Maznah Wan Omar ; Lee Chee KEONG

Malaysian Journal of Microbiology.2018;14(2):137-144.

Aims:In this study, ten indigenous microalgae samples from freshwater and marine waters from Malaysia, cultured and analysed on proximate and biochemical analysis. The proximate and biochemical analysis consists of starch, carbohydrates, lipid, protein, ash and moisture contents. This study was more focused on screening of starch accumulation in marine and freshwater microalgae cultures. Methodology and results:Based on screening, the results showed that Chlorella salinacontents highest starch of 4.92±0.33%, followed by Spirulinasp. 2.58±1.18%, Isochrysis maritime 0.99±0.33%, and lastly for Nitzschiapanduriformisand Naviculadistanscontents similar percentage of starch (0.44±0.10 and 0.40±0.07%, respectively). Besides starch analysis, proximate analyses(ash, moisture, lipid, protein, and carbohydrates) have been conducted. The results obtained indicated that all the cultures contain more than 4.50% of carbohydrates in average, followed by lipid and protein <1%. The results demonstrate that further optimization and various harvesting stages (early of exponential phase, early of stationary phaseand late stationary phase) may increase lipid, carbohydrates, starch, and protein accumulation. Chlorella salinaand Spirulinasp. will be used to further study on optimization of physical and chemical factors for high starch accumulation. Conclusion, significance and impact of study:In conclusion, this experiment focused more on preliminary screening for further application of starch uses in food and food packaging indust

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