Cunninghamella bainieri 2A1 is an oleaginous fungus whose lipid accumulation profile is significantly influenced by metal ion concentrations in growth medium. Mg2+, Fe3+, Mn2+ and Cu 2+ were found to be the important elements affecting lipid accumulation in this fungus. This study employs a statistical method (Response Surface Methodology - RSM) to study the combined effects of Mg2+, Fe3+, Mn2+ and Cu2+ on lipid accumulation of C. baineri 2A1. Cultivation was carried out in 250 mL Erlenmeyer flasks containing 100 mL nitrogen limited medium at 30�C and 250 rpm agitation for 120 h. A thirty-run central composite design experiment was employed to identify and optimize the significant factors. In addition to Mg2+ and Fe 3+ which were shown to have significant effects on lipid accumulation, the interactions between Mg2+ and Cu2+, as well as the effect of Cu2+ in quadratic terms were also found to have significant effect on the process (p<0.05). The highest amount of lipid obtained in this study was 39% g/g biomass with optimal levels of Mg 2+, Fe3+ and Cu2+ at 5.00, 0.017 and 0.0005 g/L, respectively, while Mn2+ was omitted. A 32% increment in lipid yield was recorded, where the lipid content increased to 38%, compared to initial yield of 29% g/g biomass prior to optimization. In conclusion, Mg 2+ and Fe3+ have significant positive effect on the lipid accumulation of this fungus, whereas Mn2+ and Cu2+ exert negative effects in combination.

Biosurfactants or microbial surfactants are structurally diverse and contribute to reducing surface and interfacial tension. Apart from being isolated from municipal waste and oil contaminated soil, biosurfactant-producing Bacillus spp. can also be found in fermented foods. Bacillus subtilis produce surfactant, which exhibits antibacterial activity against various pathogenic bacteria. In this study, surfactant-producing Bacillus were isolated from traditional fermented food namely; budu (fish sauce), cincalok (fermented small shrimps), tempeh (fermented soybeans) and tapai ubi kayu (fermented cassava). Identification of surfactin-producing bacteria was conducted using 16S rRNA which indicated that surfactin-producing strains isolated from budu and tempeh are Bacillus subtilis while strains from cincalok and tapai ubi kayu are Bacillus amyloliquefaciens with a sequence similarity of 99%. Characterization of surfactin was carried out by High-Performance Liquid Chromatography (HPLC) and Liquid Chromatography-Mass Spectrometry (LCMS). HLPC analyzes identified major peaks contributing to the presence of surfactin. LCMS analysis detected specific mass to charge ratio (m/z) which contributed to the presence of maximum thirteen surfactin isoforms. Surfactin produced by the isolated strains also exhibited antibacterial activity toward pathogenic bacteria, namely Bacillus cereus, Listeria monocytogenes, Staphylococcus aureus, Streptococcus pneumoniae, Salmonella Typhimurium, Serratia marcescens and Klebsiella pneumoniae. All isolated strains from the Malaysian fermented food types investigated in this study were able to produce surfactin. In addition, antibacterial screening via agar well diffusion, measurements of MBC and MIC show surfactin produced by the isolated strains have antibacterial activities toward certain Gram-positive and Gram-negative bacteria tested in this study.

A new solvent-producing Clostridium has been isolated from soil used in intensive rice cultivation. The 16S rRNA analysis of the isolate indicates that it is closely related to Clostridium acetobutylicum, with a sequence identity of 96%. The new isolate, named C. acetobutylicum YM1, produces biobutanol from multiple carbon sources, including glucose, fructose, xylose, arabinose, glycerol, lactose, cellobiose, mannitol, maltose, galactose, sucrose and mannose. This isolate can also utilize polysaccharides such as starch and carboxylmethyl cellulose (CMC) for the production of biobutanol. The ability of isolate YM1 to produce biobutanol from agro-industrial wastes was also evaluated for rice bran, de-oiled rice bran, palm oil mill effluent and palm kernel cake. The highest concentration of biobutanol (7.27 g/L) was obtained from the fermentation medium containing 2% (w/v) fructose, with a total acetone-butanol-ethanol (ABE) concentration of 10.23 g/L. The ability of isolate YM1 to produce biobutanol from various carbon sources and agro-wastes indicates the promise of the use of this isolate for the production of biobutanol, a renewable energy resource, from readily available renewable feedstocks. 2015 Elsevier Ltd.

A kinetic model of bacterial growth and metabolite production can adequately explain the trends and interaction of important parameters in a fermentation process. Production of surfactin by two bacterial strains, namely, Bacillus subtilis MSH1 and Bacillus subtilis ATCC 21322, in a 5 L bioreactor was investigated using Cooper's media with 4% (v/v) glucose. The present kinetic study was carried out in order to determine the correlation between microbial cell growth, surfactin production and glucose consumption. Batch fermentation was performed by cultivation of each selected strain in a bioreactor at 30�C for 55 h. The experimental results showed production of surfactin in the culture medium after 5 and 10 h of incubation for B. subtilis ATCC 21332 and B. subtilis MSH1, respectively, at which the bacterial cells were at an early stage of the log phase. The maximum concentration of surfactin (Pmax) achieved by B. subtilis MSH1 and B. subtilis ATCC 21332 was 226.17 and 447.26 mg/L, respectively. The kinetic study of bacterial cell growth of both strains indicated that B. subtilis MSH1 had a specific growth rate (?max) of 0.224 h-1 and attained a maximum biomass concentration (Xmax) as high as 2.90 g/L after 28 h of fermentation, while B. subtilis ATCC 21332, with ?max of 0.087 h-1, attained an Xmax of 2.62 g/L after 45 h of incubation. B. subtilis MSH1 showed higher growth kinetics, thus exhibited higher values of ?max and Xmax compared with B. subtilis ATCC 21332 under identical fermentation conditions. The Pmax achieved by B. subtilis ATCC 21332 was 447.26 mg/L, two times higher than that achieved by B. subtilis MSH1 (226.17 mg/L). The results obtained provide kinetics information including values of Pmax, ?max and Xmax for better understanding of interactions of bacterial cell growth and glucose consumption towards surfactin production by a commercial strain of B. subtilis ATCC 21332 and a local isolate of B. subtilis MSH1.

Thraustochytrids are marine protists belonging to the class Labyrinthula of the kingdom Chromista. This group of microbes is considered a promising alternative source of high-valued omega-3 oils, especially docosahexaenoic acid (DHA, C22:6. n3), replacing fish oil which is the current major source of DHA and eicosapentaenoic acid (EPA, C20:5. n3). Our new isolate, SW1, was considered to be an Aurantiochytrium based on its morphology, fatty acid profile and molecular phylogenetic analysis. Microscopic observations revealed that SW1 has high similarity to Aurantiochytrium limacinum ATCC MYA-1381 (SR21), possessing spherical vegetative cells which undergo repeated bipartition to form diads, tetrads, octads and zoosporangia that release motile zoospores. When cultivated in four different media, SW1 produced the highest biomass (13.17. g/L) and DHA (3.6. g/L) in a medium composed of glucose, sea salt, monosodium glutamate (MSG) and yeast extract. Visualization of lipid droplet development in SW1 using Sudan Black B dye revealed that lipid droplets enlarge to occupy almost the entire cell volume within 72 to 96. h of cultivation. This strain was also found to be able to utilize various saccharides as carbon source. The results of this study show that Aurantiochytrium sp. SW1 is a potential candidate to be developed as commercial microbial DHA producer. � 2015 Elsevier B.V.

Strategic feeding of ammonium and metal ions (Mg2+, Mn 2+, Fe3+, Cu2+, Ca2+, Co 2+, and Zn2+) for enhanced GLA-rich lipid accumulation in C. bainieri 2A1 was established. When cultivated in nitrogen-limited medium, the fungus produced up to 30% lipid (g/g biomass) with 12.9% (g/g lipid) GLA. However, the accumulation of lipid stopped at 48 hours of cultivation although glucose was abundant. This event occurred in parallel to the diminishing activity of malic enzyme (ME), fatty acid synthase (FAS), and ATP citrate lyase (ACL) as well as the depletion of metal ions in the medium. Reinstatement of the enzymes activities was achieved by feeding of ammonium tartrate, but no increment in the lipid content was observed. However, increment in lipid content from 32% to 50% (g/g biomass) with 13.2% GLA was achieved when simultaneous feeding of ammonium, glucose, and metal ions was carried out. This showed that the cessation of lipid accumulation was caused by diminishing activities of the enzymes as well as depletion of the metal ions in the medium. Therefore, strategic feeding of ammonium and metal ions successfully reinstated enzymes activities and enhanced GLA-rich lipid accumulation in C. bainieri 2A1. � 2014 Shuwahida Shuib et al.