Efficient Production of Acid-Form Sophorolipids from Waste Glycerol and Fatty Acid Methyl Esters by Candida floricola.

We discovered that Candida floricola ZM1502 is capable of selectively producing the promising hydrophilic biosurfactants, acid-form sophorolipids (SLs), from glycerol. However, productivity was very low (approximately 3.5 g L-1) under the initial culture conditions. Here, we describe the design of culture medium for abundant production of acid-form SLs by C. floricola ZM1502 using waste glycerol and hydrophobic substrates in order to develop a method for SL production and disposal of waste glycerol produced by oleo-chemical industries. Urea provided the best nitrogen source for acid-form SL production from glycerol among four nitrogen sources tested [urea, NaNO3, NH4NO3, and (NH4)2SO4]. Among carbon sources we compared, hydrophobic substrates (soybean oil and oleic acid) led to productivities of approximately 20 g L-1, indicating that hydrophobic substrates provided fatty acid moieties for SL production. Addition of olive oil and oleic acid to waste glycerol enhanced acid-form SL production to 42.1 ± 0.9 and 37.5 ± 3.4 g L-1, respectively. To develop a potential industrial process, we explored other suitable hydrophobic substrates for SL production, which were obtained on site from oleo-chemical industries. Alkyl C18 esters (Pastell M-182), along with waste glycerol, increased acid-form SL production to 48.0 ± 3.4 g L-1 over a 7-d period. Furthermore, we demonstrated abundant production of acidic SLs at the mini-jar fermenter scale, obtaining 169 g L-1 over 180 h using a fed-batch cultivation technique. Efficient acid-form SL production by C. floricola could have a great impact on the development of bio-industrial processes using waste glycerol as a substrate.

Selective Production of Acid-form Sophorolipids from Glycerol by Candida floricola.

Biosurfactants (BSs) are produced in abundance from various feedstocks by diverse microorganisms, and are used in various applications. In this paper, we describe a new yeast isolate that produces glycolipid-BSs from glycerol, with the aim of enhancing the utilization of the surplus glycerol produced by the oleo-chemical industry. As a result of the screening, strain ZM1502 was obtained as a potential producer of BS from glycerol. Based on TLC analysis, the strain produced glycolipid BSs. According to structural analyses (NMR, MALDI-TOF MS, and GC-MS), the main component of the glycolipids was 6',6"-di-O-acetylated acid-form sophorolipid (SL). Interestingly, the strain produced only acid-form SL, without lactone-form SLs, although the conventional SL-producing yeast, Starmerella bombicola, produces lactone-form SLs with small amounts of the acid-form. Based on taxonomy, the strain was identified as Candida floricola. It produced 3.5 g L-1 of acid-form SLs in 20% (w/v) glycerol. In addition, C. floricola CBS7290 and NBRC10700T also produced only acid-form SLs from glycerol. These results suggest that C. floricola would enhance the utilization of waste glycerol as a fermentation feedstock and facilitate a broad range of applications for SLs.

Isolation of yeast candidates for efficient sophorolipids production: their production potentials associate to their lineage.

Eleven biosurfactant-producing strains were newly isolated from environmental samples using a drop-collapse assay and thin-layer chromatography (TLC). According to the TLC analysis, the separation patterns of the glycolipid spots of nine dominant strains corresponded to that of the sophorolipids produced by a Starmerella bombicola type strain. The retention factor values of the spot patterns of two strains were less than those of the others. Two representative major products were purified, and their molecular structures were determined. The major products were identified as diacetylated lactonic and acidic sophorolipids. The fatty acid moieties of both compounds were estimated to be 17-hydroxymethyl hexadecenoic acid. The amounts of glycolipids ranged from 5.0 to 22.9 g/L after 4 d of cultivation. According to a phylogenetic analysis, the strains were identified as Starmerella bombicola and Candida floricola.

Microhabitats occupied by Myxomycetes in the Brazilian Atlantic Forest: Heliconiaceae inflorescences / Microhabitats ocupados por Myxomycetes na Floresta Atlântica Brasileira: inflorescências de Heliconiaceae

Abstract The occurrence of Myxomycetes in Heliconia psittacorum L.f. inflorescences was researched within four conservation units located in Northeast Brazil, aiming at evaluating the occupation of this microhabitat in fragments of Atlantic Forest along an altitude between 30-750 m. Inflorescences attached to the plant were examined; dead flowers and bracts were collected to assemble moist chambers (368). Four families, four genera and 10 species were recorded. A preference was evidenced for a basic pH substrate and a predominance of calcareous species (5:1). The composition of the myxobiota in fragments pertaining to altitudes above 400 m was similar and differed significantly from the one found in fragments of lowland forests (<100 m). Physarum compressum and Arcyria cinerea are the most characteristic species of the studied myxobiota.

Resumo A ocorrência de mixomicetos em inflorescências de Heliconia psittacorum L.f. foi pesquisada em quatro unidades de conservação situadas no Nordeste do Brasil, visando avaliar a ocupação deste microhabitat em fragmentos de Floresta Atlântica, numa faixa altitudinal de 30-750 m. Foram examinadas partes mortas de inflorescências ainda presas à planta; flores e brácteas mortas foram colhidas para montagem de câmaras-úmidas (368). Foram registrados quatro famílias, quatro gêneros e 10 espécies. Evidenciou-se preferência para substrato com pH básico e predominância de espécies calcárias (5:1). A composição da mixobiota nos fragmentos de altitudes acima de 400 m foi semelhante e diferiu significativamente da encontrada nos fragmentos de florestas de terras baixas (<100 m). Physarum compressum e Arcyria cinerea são as espécies mais características da mixobiota estudada.