Enhanced ethanol production at commercial scale from molasses using high gravity technology by mutant S. cerevisiae

Abstract Very high gravity (VHG) technology was employed on industrial scale to produce ethanol from molasses (fermented) as well as by-products formation estimation. The effect of different Brix° (32, 36 and 40) air-flow rates (0.00, 0.20, 0.40, and 0.60 vvm) was studied on ethanol production. The maximum ethanol production was recorded to be 12.2% (v/v) at 40 Brix° with 0.2 vvm air-flow rate. At optimum level aeration and 40 Brix° VHG, the residual sugar level was recorded in the range of 12.5-18.5 g/L, whereas the viable cell count remained constant up to 50 h of fermentation and dry matter production increased with fermentation time. Both water and steam consumption reduced significantly under optimum conditions of Brix° and aeration rate with compromising the ethanol production. Results revealed VHG with continuous air flow is viable technique to reduce the ethanol production cost form molasses at commercial scale.

Ethanol fermentation of sugarcane molasses by Zymomonas mobilis MTCC 92 immobilized in Luffa cylindrica L. sponge discs and Ca-alginate matrices

Bio-ethanol production from cane molasses (diluted to 15 % sugar w/v) was studied using the bacterium, Zymomonas mobilis MTCC 92 entrapped in luffa (Luffa cylindrica L.) sponge discs and Ca-alginate gel beads as the immobilizing matrices. At the end of 96 h fermentation, the final ethanol concentrations were 58.7 ± 0.09 and 59.1 ± 0.08 g/l molasses with luffa and Ca-alginate entrapped Z. mobilis cells, respectively exhibiting 83.25 ± 0.03 and 84.6 ± 0.02 % sugar conversion. There was no statistical significant difference (Fischer's LSD) in sugar utilization (t = 0.254, p <0.801) and ethanol production (t =-0.663, p <0.513) between the two immobilization matrices used. Further, the immobilized cells in both the matrices were physiologically active for three more cycles of operation with less than 15 % decrease in ethanol yield in the 4th cycle, which was due to some leakage of cells. In conclusion, luffa sponge was found to be equally good as Ca-alginate as a carrier material for bacterial (Z. mobilis. cell immobilization for ethanol production. Further, it has added advantages such as it is cheap, non-corrosive and has no environmental hazard.

Production and characterization of PHA from recombinant E. coli harbouring phaC1 gene of indigenous Pseudomonas sp. LDC-5 using molasses

Polyhydroxyalkanoates (PHA) are biodegradable and biocompatible green thermoplastics, synthesized by wide variety of bacteria as an intracellular carbon and energy storage intermediate. They are used as an alternative to nonrenewable petroleum derived plastics. The current interest in these biopolyesters is stimulated by the search for cost-effective capitalized production. This paper attempts to achieve maximized production rate from recombinant system using inexpensive substrate. Molasses from agro-industrial waste was used to produce PHA from recombinant E.coli in batch culture. PHA yield in molasses (3.06g/L ± 0.05-75.5 percent) was higher than that of sucrose (2.5g/L ± 0.05 - 65.1 percent). Properties of the polymer produced from molasses and sucrose were analyzed by DSC, TGA, DTA, GC/MS, TLC and optical rotation studies. The findings suggested that molasses enhanced PHA production in recombinant E.coli.

Construction of killer industrial yeast Saccharomyces cerevisiae HAU-1 and its fermentation performance

Saccharomyces cerevisiae HAU-1, a time tested industrial yeast possesses most of the desirable fermentation characteristics like fast growth and fermentation rate, osmotolerance, high ethanol tolerance, ability to ferment molasses, and to ferment at elevated temperatures etc. However, this yeast was found to be sensitive against the killer strains of Saccharomyces cerevisiae. In the present study, killer trait was introduced into Saccharomyces cerevisiae HAU-1 by protoplast fusion with Saccharomyces cerevisiae MTCC 475, a killer strain. The resultant fusants were characterized for desirable fermentation characteristics. All the technologically important characteristics of distillery yeast Saccharomyces cerevisiae HAU-1 were retained in the fusants, and in addition the killer trait was also introduced into them. Further, the killer activity was found to be stably maintained during hostile conditions of ethanol fermentations in dextrose or molasses, and even during biomass recycling.

Análises microbiológicas do açúcar mascavo / Microbiolgical analyzes for brown sugar

Mascavo é um tipo de açúcar não refinado com um intenso sabor de melaço. Sua produção, praticamente artesanal, o torna, na maioria das vezes, susceptível as contaminações microbiológicas. Com o objetivo de se conhecer a qualidade microbiológica do açúcar mascavo comercializado, foram coletadas amostras de diferentes produtores que comercializam este tipo de açúcar no mercado. As avaliações foram realizadas com relação ao teor de umidade e a presença de bactérias mesófilas aeróbias totais, bactérias termófilas aeróbias produtoras de H2S (Desulfotomaculum nigrificans), bactérias termófilas anaeróbias não produtoras de H2S (Clostridiun thermosaccharolyticum), bactérias termófilas aeróbias totais e "flat sour", bolores e leveduras e coliformes totais e fecais. Os teores médios de umidade para as amostras de açúcar mascavo analisados variaram de 2,14 a 3,66 por cento, ou seja, de 7 a 11 vezes maior que as médias de umidade do açúcar cristal branco. Este fato explica o reduzido tempo para consumo deste produto. Pelas análises das amostras efetuadas nos últimos três anos observou-se que o açúcar mascavo produzido recentemente possui menor teor de umidade que em anos anteriores. Os resultados das análises microbiológicas mostraram que as marcas dos açúcares mascavos analisados estavam de acordo com os padrões oficiais de qualidade para bactérias termófilas anaeróbias produtoras de H2S (Desulfotomaculum nigrificans), Salmonella e bactérias do grupo coliformes. Entretanto, constataram-se contaminações a níveis críticos para bactérias mesófilas, bolores e leveduras, depreciando a qualidade do açúcar e comprometendo o tempo de armazenamento.

Brown Sugar is a type of unrefined sugar with a strong molasses flavour. Its production, is almost entirely handmade, and thus, susceptible to microbiological contamination. The aim of this research was to evaluate the brown sugar microbiological quality at different production regions, and commercialized at the supermarkets. Samples of crystal, refined and raw sugars were analyzed. The moisture, aerobic mesophile, thermophilic anaerobic, H2S aerobic thermophile (Desulfotomaculum nigrificans), H2S aerobic thermophile (acid nonproducing) (Clostridiun thermosaccharolyticum), flat sour, moulds, yeasts, Salmonella and coliforms were analyzed as well. The moisture of brown sugar ranged from 2.14 to 3.66 percent. These data are ten times the moisture level found for crystal sugar samples. Therefore, the shelf time for the brown sugar is reduced drastically. The microbiological analyzes showed the brown sugar samples meet the requirements established by the Comission on Microbiological Specification for Foods for H2S-producing aerobic thermophile (Desulfotomaculum nigrificans), Salmonella and coliforms. Contamination by mesophile bacteria, mould and yeast was critical for some samples, and therefore, decreases the quality of sugar and reduces storage time.

Screening of different fungi for decolorization of molasses / Triagem de fungos para descoloramento de melaço

The decolorization of molasses by 17 different fungi in 2 media was studied. Trichoderma viride showed the highest decolorization yield (53.5%) when cultivated at 30ºC for 7 days in Medium 1 which contained the molasses which was diluted to 40 g/L in distilled water. The other Trichoderma species and Penicillium sp. also gave similar results of 40-45%. Decolorization yield was increased by adding peptone and yeast extract to the production medium except Penicillium sp. Growth rate was not related to decolorization yet pH value was. When the pH decreased below 5.0 after the incubation, the decolorization yield increased. Although reducing sugar in culture broth decreased with decreasing color intensity, there was no connection between protein utilization and decolorizing activity.

Este estudo avaliou o descoloramento do melaço por 17 fungos em dois meios. Trichoderma viride apresentou o melhor rendimento de descoloramento (53,5%) quando cultivado a 30ºC por 7 dias no meio 1, composto de melaço diluído a 40 g/L em água destilada. As outras espécies de Trichoderma e Penicillium sp apresentaram rendimento da ordem de 40-45%. O rendimento de descoloramento aumentou com a adição de peptona e extrato de levedura ao meio de produção, com exceção de Penicillium sp. A taxa de crescimento não teve relação com o descoloramento, mas o pH sim. Quando o pH diminuiu para abaixo de 5,0 depois da incubação, o rendimento de descoloramento foi maior. Embora os açúcares redutores no meio de cultura tenham diminuído com a diminuição da intensidade de cor, não houve relação entre utilização de proteína e atividade descolorizante.

Glucosyltransferase production by Klebsiella sp. K18 and conversion of sucrose to palatinose using immobilized cells / Produção de glicosiltransferase por Klebsiella sp. K18 e conversão de sacarose em palatinose utilizando células imobilizadas

The strain Klebsiella sp. K18 produces the enzyme glucosyltransferase and catalyses the conversion of sucrose to palatinose, an alternative sugar that presents low cariogenicity. Response Surface Methodology was successfully employed to determine the optimal concentration of culture medium components. Maximum glucosyltransferase production (21.78 U mL-1) was achieved using the optimized medium composed by sugar cane molasses (80 g L-1), bacteriological peptone (7 g L-1) and yeast extract (20 g L-1), after 8 hours of fermentation at 28ºC. The conversion of sucrose to palatinose was studied utilizing immobilized cells in calcium alginate. The effects of the alginate concentration (2-4%), cell mass concentration (20-40%) and substrate concentration (25-45%) were evaluated and the yield of palatinose was approximately 62.5%.

A linhagem Klebsiella sp. K18 produz a enzima glicosiltransferase que catalisa a conversão de sacarose em palatinose, um açúcar alternativo que apresenta baixa cariogenicidade. Metodologia de Superfície de Resposta foi empregada com sucesso para determinar a concentração ótima dos componentes do meio de cultivo. A máxima produção deglicosiltransferase (21,78 U mL-1) foi obtida utilizando o meio de cultivo otimizado composto por melaço de cana de açúcar (80 g L-1), peptona bacteriológica (7 g L-1) e extrato de levedura (20 g L-1), após 8 horas de fermentação a 28ºC. A conversão desacarose em palatinose foi estudada utilizando células imobilizadas em alginato de cálcio. Os efeitos da concentração de alginato (2-4%), concentração de massa celular (20-40%) e concentração de substrato (25-45%) foram avaliados e a porcentagem de palatinose foi de aproximadamente 62,5%.

Supplementation of sugarcane bagasse with rice bran and sugarcane molasses for shiitake (Lentinula edodes) spawn production

The purpose of this study was to assess the myceliation rate, mycelial vigor and "estimated biomass" of Lentinula edodes (Berk.) Pegler, grown on a sugarcane bagasse substrate enriched with rice bran and sugarcane molasses for spawn production. The proportions of rice bran used were 0, 10, 15, 20, 25, 30 and 40 percent (dry weight/dry weight of bagasse) and the sugarcane molasses concentrations tested were 0, 10, 20, 30, 40, 50 and 60 g/kg (dry weight/dry weight of bagasse plus rice bran). The myceliation rate was decreased by the addition of the higher quantities of rice bran. The 25 and 30 percent rice bran proportions induced the highest stimulation of mycelial vigor. The addition of sugarcane molasses did not change myceliation rate or mycelial vigor. The "estimated biomass" values were similar when intermediate rice bran proportions were used and for all sugarcane molasses concentrations. Based on response surface obtained for the "estimated biomass" data, higher values were obtained with substrates containing 20 to 25 percent rice bran combined with 10 to 30 g sugarcane molasses, although the latter supplement was not considered to stimulate L. edodes growth.

Shiitake (lentinula edodes) production on a sterilized bagasse substrate enriched with rice bran and sugarcane molasses

This investigation was performed to evaluate the biological efficiency (BE), mean mushroom weight (MMW), mean number of mushroom (MNM) and mushroom quality of Shiitake [ Lentinula edodes (Berk.) Pegler] when grown on a sterilized substrate composed by sugarcane bagasse enriched with rice bran and sugarcane molasses. The proportions of rice bran were 0, 15, 20, 25 and 30 percent (dry weight/dry weight of bagasse); and the concentrations of sugarcane molasses were 0, 30 and 60 g/kg (dry weight/dry weight of bagasse plus rice bran). Four flushes were obtained during the production cycle, providing 3 accumulated productions which were used for production analysis. The substrate supplemented with 25 and 30 percent rice bran yielded the highest BE (98.42 and 99.84 percent, respectively, about 230 days after spawning) and MNM and initially produced a lower MMW than the substrates supplemented with 15 and 20 percent rice bran. Any amount of rice bran added to the sugarcane bagasse improved mushroom quality, with the best production of marketable mushrooms obtained by the addition of 15 percent rice bran. The largest amount of sugarcane molasses (60 g/kg) increased BE (90.3 and 23.6 percent, on first and second accumulated productions, respectively) and MNM and no quantity affected mushroom quality.