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Denitrification and nitrate-ammonification are the responsible processes for nitrate removal in the estuaries. Temperature, nitrate and organic carbon availability are key factors controlling a rate of the nitrate reduction processes. This mixed cultures chemostat study investigates the competition ability and their nitrate reduction end-products of the bacteria isolated from an estuary at different temperatures. This study will help us to understand the seasonal nitrate reduction processes in an estuary. The experiments showed that a nitrate-ammonifier was the predominant process in the steady-state chemostat at high temperature. While a facultative denitrifier-nitrate ammonifier was the predominant process at low temperature. However, the main end products of nitrate reduction at high temperature were up to 61% N2 indicating a denitrifier still had an important role in the end products of nitrate reduction in the estuary. The data also showed that a nitrite respiring bacterium reduced nitrite to N2, that responsible for approximately 6-9% of total N2 produced in the culture. This study confirmed that nitrate ammonifiers out-compete denitrifiers at high temperature, however, denitrifiers still had an important role in end products of nitrate reduction. [ABSTRACT FROM AUTHOR]

Electrogen is a microbial group that plays an important role as anodic biocatalyst of microbial fuel cells (MFCs), one of the most extensively studied microbial-based technologies for bioelectricity generation. The aims of this research were to isolate potential electrogenic bacteria from aquaculture pond sediments and conduct a thorough evaluation on the MFCs' electricity production and efficiency parameters. A total of 18 electrogenic bacteria having various electrochemical abilities was successfully isolated using thioglycollate solid media enriched with Fe3+. Five isolates (namely KCf1, KCf2, KCf4, KCf10, and KCf14) were non-pathogenic electrogens and able to produce relatively stable and high open-circuit voltage values (690–810 mV) on glucose-fed MFCs. Further evaluations on electricity production in close-circuit mode (fixed resistor technique, polarization tests, and analysis of power overshoot phenomenon) and efficiency parameters (Coulombic and energy efficiencies) showed that KCf2, molecular identified as Bacillus altitudinis AC11.2, was the most potential MFC biocatalyst among all isolates. It produced an MPP value of 67.11 mW m−2, current density of 333.03 mA m−2, and Coulombic and energy efficiency of 53.86% and 63.27%, respectively. Efforts to increase the MFC's electrical output have been done by assembling four reactors in series and parallel circuits, obtaining the maximum total voltage of 1.6–2.0 V (for series configuration). This potential output was higher than a portable zinc–carbon battery (1.5 V) and a Ni–Cd battery (1.2 V). However, the voltage reversal suffered in series circuits was another challenge in the development of MFCs for bioelectricity production, since the existence of this phenomenon due to biological factors (microbial metabolism dynamics) are not easy to be controlled. [ABSTRACT FROM AUTHOR]

Microbial fuel cell (MFC), a bio-electrochemical device that exploits electroactive microbes, has gained more attention in developing countries, such as Indonesia. Unfortunately, studies related to bio-electrochemistry are often constrained due to the need for precise and high-cost instrumentation, such as data logger/acquisition or data logging-multimeter for continuously monitoring electricity generation of MFCs in the rigid time interval. This present work aimed at two issues: (1) to evaluate the use of a low-cost microcontroller-based data logger, the developed multi-channels Arduino UNO-based data logging system, for monitoring the electricity generation of ten MFC bioreactors simultaneously, and (2) to evaluate the electrochemical performance of MFCs biocatalysts by ten electroactive microbes isolated from aquaculture pond sediment in Indonesia. The monitoring system worked with a multi-channels Arduino UNO, a multiplexer, an external 16-bit ADC (analogue to digital converter) ADS1115, and a RTC (real time clock) module. The MFC performance was evaluated in the terms of open circuit voltage and close circuit voltage (polarization curve, power density, and losses). Statistical analysis confirmed the high accuracy of the developed system with the average of absolute and relative error values of 1.21 mV and 1.26%, respectively, comparable to traditional multimeter utilized for MFC electricity measurement. These results suggested that the developed data logging system could be a considerable option as a low-cost monitoring device for electrochemical studies of MFCs. Electrochemical performances of ten anodic biocatalysts were also evaluated, suggesting that there were three effective bacteria (isolate KCf2, KCf4, and KCf10) for producing relatively stable bioelectricity in the reactor of MFCs. These three electroactive microbes can produce power density of 0.069 W m−2, 0.021 W m−2, and 0.010 W m−2, respectively. [ABSTRACT FROM AUTHOR]

Oil palm plantations are the most invasive land use changes in Southeast Asia. It must have affected unique natural biodiversity. This study aimed to investigate the diversity of soil bacteria based on 16S rRNA gene profiles from tropical forest and oil palm plantation in Jambi Province, Indonesia. Soil sample was taken from tropical forest and oil palm plantation from Jambi province, Indonesia. The forest site is in Bukit Duabelas National Park, and the nearby oil palm plantation is in Sarolangun District, Jambi Province, Indonesia. The diversity of bacterial communities from topsoil was studied using Denaturing gradient gel electrophoresis (DGGE) of 16S rRNA gene and common biodiversity indices. PCR amplification of 16S rRNA gene was successfully conducted primers-using 33F/518R primers. Phylogenetic approach was used for revealing the community shift of bacterial phyla and genera in both areas. Phylogenetic analysis showed there were 4 phyla of bacteria i.e., Firmicutes, Alphaproteobacteria, Gammaproteobacteria, and Actinobacteria, respectively. Actinobacteria was the most dominant group in both areas. The composition of soil bacterial community in the oil palm plantation, based on total number of bands 16S rRNA generated from DGGE was richer than that in the Bukit Dua Belas National Park. It was probably caused by plantation year circle more than 10 years and routine activities during the plantation management, such as applications of agricultural lime, herbicide and fertilizer. [ABSTRACT FROM AUTHOR]

Certain strains of V. parahaemolyticus carry a gene that encodes a toxin that causes Acute hepatopancreatic necrosis disease (AHPND) in P. vannamei. AHPND attacks shrimp post larvae within 20-30 days after stocking causing up to 100% mortality. The expression of these virulent genes is controlled by the quorum sensing system. This system is inhibited by an anti-quorum sensing (AQS) mechanism. Several Bacillus strains have AQS mechanism by producing AHLLactonase enzyme. Therefore, this study aimed to obtain Bacillus spp. having AQS activity for controlling AHPND. The study was conducted from isolation and selection of Bacillus isolates, as well as determination of AQS activity. From 22 samples consisting of shrimp intestines, water and pond sediment samples, a total of 151 isolates of Bacillus spp. were isolated. The screening test for AQS activity obtained 11 isolates that showed AQS activity on Cromobacterium violaceum. Determination of violacein pigment in liquid cultures of C. violaceum showed the index value of the pigment formation was between 0.025-0.166 and 0.026-0.567 at 24-hour and between 48-hour incubations, respectively. The quantitative analysis of violacein production showed that there were six isolates of Bacillus could inhibit the pigment production more than 75%. The isolates were identified as Bacillus cereus (four isolates), Bacillus thuringiensis (one isolate), and Bacillus velezensis (one isolate), respectively. The molecular analysis had confirmed that the isolates have aiiA genes encoding AHL-lactonase enzyme. These Bacillus isolates have potential application for controlling AHNPD disease. [ABSTRACT FROM AUTHOR]

During tempeh production, boiling was considered as heat treatment that could significantly reduce or eliminate bacterial population in soybean before fungal inoculation. The objective of this study was to enumerate and trace Enterobacteriaceae communities in pre-boiling soybean, post-boiling soybean, and fresh tempeh designated as RTI and EMP. Standard plate count and qRT-PCR were employed to determine the culturable and non-culturable bacteria, while Enterobacterial Repetitive Intragenic Consensus PCR was conducted to determine the intraspecies genomic variations. Fresh tempeh from both RTI and EMP contained approximately 107 and 108 CFU/g of Enterobacteriaceae respectively. The number of bacteria in pre-boiling soybean were 10,000 times lower than in fresh tempeh. Our study showed that most Enterobacteriaceae were severely injured or quiescent during boiling process and quickly recovered up to 109 CFU/g in fresh tempeh. Some Klebsiella isolates found in tempeh were genetically identical to isolates in soybean, but different from those of medical isolates. This study suggested that soybean could be the main origin of Klebsiella in fresh tempeh. [ABSTRACT FROM AUTHOR]

Prebiotic administration is one method to increase growth performance, improve intestinal microbiota composition, inhibit pathogen growth and induce immunity in fishes. Honey consists of oligosaccharides as the major content that can be used as a prebiotic. This study investigated the effects of administration of dietary prebiotic from honey at different doses on growth performance, digestive enzyme activities, intestinal microvilli, short‐chain fatty acid contents and microbiota diversity in the digestive tract of Nile tilapia (Oreochromis niloticus). Four diet treatments were applied, namely control (without honey administration) and honey administration at 0.25%, 0.5% and 1% doses (g/kg diet). Nile tilapia weighing 20 ± 1.72 g were reared with these diet treatments for 30 days. Results demonstrated that honey prebiotic administration could increase growth performance; provide a lower feed conversion ratio; induce digestive enzyme activities (amylase, protease and lipase); increase microvilli length, perimeter ratio, density of intestinal microvilli and short‐chain fatty acid contents (propionate, iso butyrate, iso‐valerate and N‐valerate); and improve microbiota diversity in the digestive tract of Nile tilapia at the best dietary dose of 1%. [ABSTRACT FROM AUTHOR]

Candidiasis has become increasingly widespread in the community alongside with the developing resistance of Candida sp. to some antifungals. A prevalence study in the present research is required to surveil the distribution of Candida-related infections to administrate the appropriate antifungal treatments. The objective of this research was to determine the species distribution of candidiasis with their antifungal susceptibility isolated from clinical specimens at the Zainoel Abidin Hospital (ZAH) Banda Aceh, Indonesia. The clinical specimens were from inpatients and outpatients in the hospital during January to June 2019. The identification of Candida species and antifungal sensitivity assay were conducted by using VITEK® 2 Compact. Of a total of 68 isolates, there were six species of Candida with the highest species prevalence was Candida tropicalis (52.94%). Additionally, the highest prevalence of candidiasis came from urine specimen (54.41%) and mostly from inpatients in the internal medicine unit (54.41%). Candidiasis occurred predominantly in men (58.82%) and during adulthood (55.88%). The antibiogram of Candida sp. shows a high percentage of sensitivity towards some antifungals including fluconazole (100%), voriconazole (100%), caspofungin (100%), micafungin (100%), amphotericin B (99.5%), and flucytosine (100%). From this result, it can be concluded that candidiasis cases in the ZAH Banda Aceh, Indonesia has prevalently occurred with the few antifungal therapies for candidiasis of were still effective empirically and definitively. This is an initial study of Candida prevalence within different clinical samples in Banda Aceh and the study is expected to be a basis for prevention and control of Candida-related infections in the area. [ABSTRACT FROM AUTHOR]

Paddy field is one of the anthropogenic sources that produce greenhouse gases emission. This study aimed to investigate the impact of methanotrophic and N2Oreducing bacterial inoculation on CH4 and N2O emissions, paddy growth and bacterial community structure in paddy field. Two treatments of 100% synthetic fertilizer (250 kg urea/ha) without biofertilizer and 50% synthetic fertilizer (125 kg urea/ha) with biofertilizer consisted of methanotrophic and N2O-reducing bacteria were applied in the paddy field. Inoculation of methanotrophic and N2O-reducing bacteria was able to reduce CH4 and N2O emission up to 4.19 mg CH4/m2/day and 351.29 µg N2O/m2/day, respectively. Those bacterial applications were also able to increase paddy growth and yield productivity. According to DGGE profile, inoculation of the biofertilizer seemed to have a transient impact on bacterial communities in paddy soil at 36 days after transplanting (DAT) which showed the lowest similarity with all samples (a similarity index of 0.68). DGGE bands successfully excised have closest relative to uncultured bacteria which comprised 5 phyla, i.e. Proteobacteria (Alphaproteobacteria and Deltaproteobacteria), Nitrospirae, Actinobacteria, Firmicutes, and Acidobacteria. In this study, Alphaproteobacteria was the most dominant phylum. We provide basic information for developing the biofertilizer which supports sustainable agriculture. [ABSTRACT FROM AUTHOR]

The virulence gene expression of phytopathogenic bacteria, such as Dickeya dadantii is regulated by quorum sensing (QS) mechanism. The QS mechanism is induced by acyl homoserine lactone (AHL) that is universal autoinducer of Gram-negative bacteria. Degradation of AHL compound can be used to control the virulence of phytopathogenic bacteria. The enzyme of AHL lactonase is encoded by the aiiA gene and can degrade the lactone ring of AHL. This study was aimed to characterize aiiA gene encoding AHL lactonase from 20 isolates of shrimp pond and soil forest, Indonesia and examine the isolates ability to reduce violacein pigment of Chromobacterium violaceum and soft rot disease symptoms caused by D. dadantii. The results showed nine bacterial isolates (B4, B10, B11, B13, B14, B16, B17, B18 and B19) containing the aiiA gene encoding AHL lactonase. Based on 16S rRNA gene identification, 9 isolates had the highest similarity with Bacillus toyonensis, B. cereus, B. thuringiensis, B. mycoides and B. subtilis. These isolates had the capability to reduce the formation of violacein pigment and the symptoms of soft rot disease in potatoes. These results show that the AHL lactonase produced by these isolates can be used as Quorum Quenching (QQ) agent to inhibit the QS mechanism [ABSTRACT FROM AUTHOR]

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Some of the methanotrophic bacteria and N2O reducing bacteria have been proven to be able to support the plant growth and increase the productivity of paddy. However effect of the methanotrophic and N2O reducing bacteria application as a biofertilizer to indigenous N2O reducing bacteria is still not well known yet. The aim of this study was to analyze the diversity of N2O reducing bacteria in lowland paddy soil based on a nosZ gene. Soil samples were taken from lowland paddy soils in Pelabuhan Ratu Sukabumi, West Java, Indonesia. There were two treatments for the paddy field soil, ie. biofertilizer-treated field 20% fertilizer (50 kg/ha) with the addition of biofertilizer and 100% fertilizer. PCR amplification of nosZ gene was successfully conducted using nosZF and nosZR primer pair. Denaturing Gradient Gel Electrophoresis (DGGE) process was conducted at 150 V for 5.5h. There were three differences nosZ bands were sequenced. The phylogenetic analysis showed that they were close to uncultured bacteria. Microbial diversity in the biofertilizer-treated field was higher than that of in the 100% fertilizer-treated field. The biofertilizer treatment has higher in microbial diversity than that of applied non-biofertilizer paddy fields. This research might have impact in the application of biofertilizers due to the emission of N2O as a green house gas from paddy fields farming activity. The biofertilizer has great potential application in sustainable environmental friendly agriculture systems. [ABSTRACT FROM AUTHOR]

Pyrene degradation and biosurfactant activity by a new strain identified as Gordonia cholesterolivorans AMP 10 were studied. The strain grew well and produced effective biosurfactants in the presence of glucose, sucrose, and crude oil. The biosurfactants production was detected by the decreased surface tension of the medium and emulsification activity. Analysis of microbial growth parameters showed that AMP10 grew best at 50 μg mL-1 pyrene concentration, leading to 96 % degradation of pyrene within 7 days. The result of nested PCR analysis revealed that this isolate possessed the nahAc gene which encodes dioxygenase enzyme for initial degradation of Polycyclic Aromatic Hydrocarbon (PAH). Observation of both tensio-active and emulsifying activities indicated that biosurfactants which produced by AMP 10 when grown on glucose could lower the surface tension of medium from 71.3 mN/m to 24.7 mN/m and formed a stable emulsion in used lubricant oil with an emulsification index (E24) of 74%. According to the results, it is suggested that the bacterial isolates G. cholesterolivorans AMP10 are suitable candidates for bioremediation of PAH-contaminated environments. [ABSTRACT FROM AUTHOR]

As a social insect, termite colony consists of three castes, i.e. reproductive, soldier, and worker castes. In their role of cellulose digestion, the worker termites use two sources of cellulolytic enzyme that include cellulases produced by the termite and the gut symbions. Macrotermes gilvus classified in mound builder termite, mostly depend on cellulolytic bacteria for cellulose digestion. This study aims to characterize cellulolytic bacteria of termite gut symbionts of worker M. gilvus and to identify the cellulolytic bacteria based on sequences of 16S ribosomal RNA (rRNA) gene. Cellulolytic bacteria of termite gut were isolated and cultured in CMC (Carboxymethyl cellulose) media. The biochemical characters of bacterial isolates were assayed using Microbact 12A and 12B. Cellulolytic activity was determined based on formation of clear zone and cellulolytic index on CMC plate media. The bacterial isolate that has the highest cellulolytic index was analyzed for its 16S rRNA gene sequences. Four isolates of cellulolytic bacteria were successfully isolated from gut of M. gilvus with aerobic and anaerobic conditions. The highest formation of cellulolytic index (2.5) was revealed by RA2. BLAST-N (Basic Local Alignment Search Tool for Nucleotides) result of 16S rRNA gene sequences of RU4 and RA2 isolates showed that the isolate has similarity with Bacillus megaterium and Paracoccus yeei, respectively. This result indicated that RA2 isolate was P. yeei, a cellulolytic bacterium of a termite gut of M. gilvus. [ABSTRACT FROM AUTHOR]

Tempeh, a well-known Indonesian fermented food made from soybeans, results from mixed-culture fermentation using a diverse group of microorganisms. The presence of many nonviable microorganisms in cooked tempeh may trigger responses in the immune system. Thirty female Sprague-Dawley rats were fed a standard diet supplemented with either non-fermented soybeans or tempeh (uncooked or cooked), for 28 days. Gene expression of intestinal immunoglobulin A (IgA) was analyzed using semi-quantitative real-time PCR, and intestinal IgA was further quantified from the ileum wash using ELISA. There was no significant ( p>0.05) difference in IgA gene expression between animals groups receiving feed supplemented with cooked or uncooked tempeh. However, a significant ( p<0.05) difference was observed between animals receiving feed supplemented with tempeh and with non-fermented soybeans. Microbial cells in tempeh might increase IgA protein secretion. [ABSTRACT FROM AUTHOR]

The research was conducted to study the metagenomic of actinomycetes based on 16S ribosomal RNA (rRNA) and bacterial nifH genes in soil and roots of four rice cultivars. The denaturing gradient gel electrophoresis profile based on 16S rRNA gene showed that the diversity of actinomycetes in roots was higher than soil samples. The profile also showed that the diversity of actinomycetes was similar in four varieties of rice plant and three types of agroecosystem. The profile was partially sequenced and compared to GenBank database indicating their identity with closely related microbes. The blast results showed that 17 bands were closely related ranging from 93% to 100% of maximum identity with five genera of actinomycetes, which is Geodermatophilus, Actinokineospora, Actinoplanes, Streptomyces and Kocuria. Our study found that Streptomyces species in soil and roots of rice plants were more varied than other genera, with a dominance of Streptomyces alboniger and Streptomyces acidiscabies in almost all the samples. Bacterial community analyses based on nifH gene denaturing gradient gel electrophoresis showed that diversity of bacteria in soils which have nifH gene was higher than that in rice plant roots. The profile also showed that the diversity of those bacteria was similar in four varieties of rice plant and three types of agroecosystem. Five bands were closely related with nifH gene from uncultured bacterium clone J50, uncultured bacterium clone clod-38, and uncultured bacterium clone BG2.37 with maximum identity 99%, 98%, and 92%, respectively. The diversity analysis based on 16S rRNA gene differed from nifH gene and may not correlate with each other. The findings indicated the diversity of actinomycetes and several bacterial genomes analyzed here have an ability to fix nitrogen in soil and roots of rice plant. [ABSTRACT FROM AUTHOR]

Calliandra calothyrsus preserved in silage is an alternative method for improving the crude protein content of feeds for sustainable ruminant production. The aim of this research was to evaluate the quality of silage which contained different levels of C. calothyrsus by examining the fermentation characteristics and microbial diversity. Silage was made in a completely randomized design consisting of five treatments with three replications i.e.: R0, Pennisetum purpureum 100%; R1, P. purpureum 75%+C. calothyrsus 25%;, R2, P. purpureum 50%+C. calothyrsus 50%; R3, P. purpureum 25%+C. calothyrsus 75%; and R4, C. calothyrsus 100%. All silages were prepared using plastic jar silos (600 g) and incubated at room temperature for 30 days. Silages were analyzed for fermentation characteristics and microbial diversity. Increased levels of C. calothyrsus in silage had a significant effect (p<0.01) on the fermentation characteristics. The microbial diversity index decreased and activity was inhibited with increasing levels of C. calothyrsus. The microbial community indicated that there was a population of Lactobacillus plantarum, L. casei, L. brevis, Lactococcus lactis, Chryseobacterium sp., and uncultured bacteria. The result confirmed that silage with a combination of grass and C. calothyrsus had good fermentation characteristics and microbial communities were dominated by L. plantarum. [ABSTRACT FROM AUTHOR]

Bacillus pumilus is a spore-forming bacteria that is rod-shaped, gram positive, and aerobic. B. pumilus produced pumilacidins, known to have toxic effects on epithelial cells. Antibiotics were usually used to treat the disease caused by bacteria. Antibiotic typing test of B. pumilus indigenous from sewage water showed that this isolate was resistant to ampicillin and clindamycin. An alternative way was by application of bacteriophages as biocontrol agents to reduce B. pumilus in environment. The aim of this study were to isolate and characterize B. pumilus bacteriophage isolated from Ciapus River in Bogor, West Java. Bacteriophages infecting B. pumilus were isolated from river water using the double agar overlay method. Phages were defined by plaque morphology, structure, host range, and characteristic of molecular weight protein phage. Phage FBa1, FBa2, and FBa3 had narrow host range and they were specific for infecting B. pumilus. Electron microscope observation showed that phage FBa1 had icosahedral head without tail (166.67 nm in diameter), so it is called phage-like particles. Characterization of phage FBa1 by SDS-PAGE showed five proteins band. Molecular weight of FBa1 proteins was 70.9, 54.9, 33.8, 28.3, and 21.4 kDa. [ABSTRACT FROM AUTHOR]

Tempeh is a well-known Indonesian fermented food made from soybean. During the fermentation process, microorganisms play an important role in the flavor, texture, and nutritional quality of tempeh. Tempeh has been show to have immuno-modulatory and immune-stimulating properties that may also be caused by the microorganisms in tempeh as they interact between the microbial population in the intestinal tract. The objective of this study was to quantify IgA gene expression at both the transcription and translation levels in Sprague Dawley (SD) rats supplemented with tempeh. A total of 6 female SD rats were divided into 3 groups of 2 rats. The first group was the control and was fed a standard diet without tempeh. The second- and third group were fed with a standard diet supplemented with raw and cooked tempeh, respectively. Ileum tissue samples were collected after tempeh supplementation for 28 days. RNA was extracted from ileum samples, and measurement of IgA gene expression was further analyzed using semi quantitative real-time PCR. The concentration of IgA protein was quantiied from ileum lysate using the half sandwich ELISA method. IgA gene expressions in rats supplemented with raw, and with cooked tempeh, were 1.18 and 1.17 fold higher, respectively, compared to the control group. Moreover, IgA protein secretion levels also increased 2.46 and 2.08 fold, respectively, compared to the control group. The result of this study indicates that both raw and cooked tempeh may stimulate IgA secretion, and also that both viable and non-viable microorganisms might stimulate IgA gene expression. [ABSTRACT FROM AUTHOR]

Bekasam is an Indonesian fermented fish product that tastes sour and mostly contains lactic acid bacteria (LAB). The aim of this study is to obtain and characterize LAB isolates from bekasam and to study their potency in inhibiting the growth of pathogenic bacteria, i.e. Escherichia coli, Salmonella typhimurium ATCC 14028, Bacillus cereus, Staphylococcus aureus and Listeria monocytogenes. LAB were isolated from bekasam using media of MRSA supplemented with CaCO3 0.5%. Incubation was at 37°C for 48 hours. The pure cultures were verified as LAB based on morphological and biochemical characteristics. Eight bekasam samples showed that the total average of LAB were 1.4 x 108 to 9.0 x 108 CFU/mL. Seventy four isolates were successfully isolated. It was found that 62 isolates (84%) belonged to LAB, and 23 isolates of them could inhibit the growth of the five pathogenic bacteria. The highest inhibition zone was accounted for S. aureus. However, neutralized supernatant of the LAB culture did not inhibit the growth of the pathogenic bacteria. These results indicate that the LAB inhibition to the pathogenic bacteria was due to the organic acid, and that perhaps the main factor in the bekasam preservation by LAB. [ABSTRACT FROM AUTHOR]

Tempeh is an Indonesian traditional fermented food produced using Rhizopus as a starter culture. In practice, however, the starter culture as well as fermentation processes would yield a polymicrobial fermentation, which generated a unique tempeh flavor and texture. This condition makes Indonesian tempeh as one of the most complex fermented food, while at the same time would make it difficult to scale up tempeh production with uniform quality and consistency. The aim of this study was to compare a number of tempeh microbial communities employing Amplified Ribosomal Intergenic Sequence Analysis (ARISA). Fresh tempeh samples were obtained from tempeh producers in Java and Moluccas. 16S rRNA gene libraries and DNA sequencing were employed to analyze further the nature of bacterial diversity in two selected tempeh samples. The results of our study showed that different tempeh producer possessed different Bacterial ARISA (BARISA) or fungi ARISA (FARISA) profiles. However, BARISA profiles were found to be more discriminative than FARISA, and therefore BARISA would be more useful for tempeh genetic fingerprint or barcoding. [ABSTRACT FROM AUTHOR]

The use of chlorate as a selective inhibitor of dissimilative nitrate reduction was studied using pure cultures of Comamonas testosteroni (a denitrifier) and Klebsiella pneumoniae (a nitrate-ammonifier) isolated from estuarine sediment, and in sediment slurry. Pure culture experiments demonstrated that chlorate selectively inhibited membrane-bound nitrate reductase (Nar) activity, probably by blocking nitrate transporters (NarK). Sediment slurry experiments showed that chlorate inhibited nitrate reduction and N2O formation, but did not inhibit nitrite reduction and its N2O formation, indicating that chlorate selectively inhibited only the first step of nitrate reduction. Chlorite chemically oxidized nitrite to nitrate and could not be used as a selective inhibitor of nitrite metabolism, although chlorite apparently selectively inhibited formation of N2O from nitrite. Chlorate can be used as a specific inhibitor to distinguish between nitrate reduction by Nap or Nar in natural communities of microorganisms. [Copyright &y& Elsevier]