Kesavan Madhavan Nampoothiri

Alpha amylase from a fungal culture grown on oil cakes and its properties

Fermentacao no Estado Solido foi empregada na producao de alfa-amilase usando Aspergillus niger. Diferentes tipos de torta foram utilizadas, como torta de oleo de coco (COC), torta de de oleo de amendoim (GOC) torta de oleo de sesamo (SOC), torta de palma (PKC) e torta de oleo de oliva (OOC) foram selecionadas para serem usadas como substratos para producao de enzima e comparadas com o farelo de trigo (WB), GOC foi escolhido por ser o que produziu maiores concentracoes de enzima. A combinacao WB e GOC (1:1) resultou em maiores titulos da enzima quando em comparacao com os substratos individuais. A maxima concentracao de enzima (9196 U/ gms) foi obtida quando a FES foi conduzida utilizando WB + GOC, com umidade de 64% e suplementada com lactose e nitrato de amonia (1% cada) a 300C por 72 horas utilizando 2 mL de uma suspensao de esporo (6x107sporos/ml). A purificacao parcial da enzima usando fracoes de sulfato de amonio resultou num aumento de 2-4 vezes o aumento da atividade. A enzima apresentou um peso molecular de 68 Kda pelo SDS_PAGE. Exceto Mn, todos os outros ions metalicos como Ca, K, Na, Mg sao inibitorios na producao da enzima.

Production, purification and structural characterization of an exopolysaccharide produced by a probiotic Lactobacillus plantarum MTCC 9510

Exopolysaccharides (EPS) from lactic acid bacteria contribute to specific rheology and texture of fermented milk products and finds applications even in non-dairy foods and in therapeutics. Box-Behnken model of response surface methodology (RSM) was employed to formulate the production medium for exopolysaccharide (EPS). FT-IR spectral analysis of the purified EPS from Lactobacillus plantarum MTCC 9510 revealed prominent characteristic groups corresponding to polyhydric alcohols. The degradation temperature (Td) of the polysaccharide was found to be 260°C with the help of thermo gravimetric analysis (TGA). Structure elucidation of the EPS showed that it consists of a trisaccharide repeating unit of α-d-glucose, β-d-glucose and α-d-mannose.

Probiotic fermented foods for health benefits

The history of fermented foods used by humans can be traced back to centuries. The medicinal as well as flavor enhancing properties of fermented foods are mainly due to the presence of bacteria known as probiotics. Probiotics aid in digestion and nutrient assimilation. These bacteria are also known for their beneficial effects for the immune system and health. Many of them produce antimicrobial bioactive molecules that make them effective biopreservatives and produce nutraceuticals to create functional foods with increased bioavailability of nutrients. Thus, these lactic acid bacteria have undeniable favorable effects. This review will summarize the health benefits of probiotic fermented foods.

Newly Isolated Lactic Acid Bacteria with Probiotic Features for Potential Application in Food Industry

Five newly isolated lactic acid bacteria were identified as Weissella cibaria, Enterococcus faecium, and three different strains of Lactobacillus plantarum by 16S rRNA sequencing. Essential probiotic requirements of these isolates such as tolerance to phenol, low pH, high sodium chloride, and bile salt concentration were checked. Efficiency in adherence to mucin and hydrophobicity of the bacterial cell were also evaluated by in vitro studies. Antimicrobial activities against some pathogens were tried, and the sensitivity of these strains against 25 different antibiotics was also checked. Further studies revealed Weissella and Enterococcus as substantial producers of folic acid. Folate is involved as a cofactor in many metabolic reactions, and it has to be an essential component in the human diet. The folate level in the fermented samples was determined by microbiological assay using Lactobacillus casei NCIM 2364 as indicator strain. The three strains of L. plantarum showed significant inhibitory activity against various fungi that commonly contaminate food stuffs indicating their potential as a biopreservative of food material.

2,4-Di-tert-butyl phenol as the antifungal, antioxidant bioactive purified from a newly isolated Lactococcus sp.

The volatile organic compound 2,4-di-tert-butyl phenol (2,4 DTBP) was purified from the cell free supernatant of a newly isolated Lactococcus sp. by solvent extraction and chromatographic techniques. Molecular characterization of the compound by ESI-MS, (1)H NMR and FTIR analysis revealed the structure, C14H22O. Fungicidal activity was demonstrated against Aspergillus niger, Fusarium oxysporum and Penicillium chrysogenum by disc diffusion assay. Among the cell lines tested for cytotoxicity of this compound (normal cell line H9c2 and cancer cell lines HeLa and MCF-7), a remarkable cytotoxicity against HeLa cells with an IC50 value of 10 μg/mL was shown. A biocontrol experiment with 2,4 DTBP supplemented fraction prevented growth of the abovementioned fungi on wheat grains. The study further strengthens the case for development of biopreservatives and dietary antioxidants from lactic acid bacteria for food applications.

Control of Spoilage Fungi by Protective Lactic Acid Bacteria Displaying Probiotic Properties

Thirty-six lactic acid bacteria belong to Lactococcus, Lactobacillus, Enterococcus, and Pediococcus were isolated, and the spectrum of antifungal activity was verified against Fusarium oxysporum (KACC 42109), Aspergillus niger (KACC 42589), Fusarium moniliforme (KACC 08141), Penicillium chrysogenum (NII 08137), and the yeast Candida albicans (MTCC 3017). Three isolates, identified as Pediococcus pentosaceus (TG2), Lactobacillus casei (DY2), and Lactococcus (BSN) were selected further, and their antifungal compounds were identified by ESI-MS and HPLC analysis as a range of carboxylic acids along with some unidentified, higher molecular weight compounds. An attempt to check out the shelf life extension of wheat bread without fungal spoilage was performed by fermenting the dough with the Lactococcus isolate. Apart from growth in low pH and tolerance to bile salts, probiotic potential of these three isolates was further substantiated by in vitro screening methods that include transit tolerance to the conditions in the upper human gastrointestinal tract and bacterial adhesion capacity to human intestinal cell lines.

Production and characterization of poly(3-hydroxy butyrate-co-3 hydroxyvalerate) (PHBV) by a novel halotolerant mangrove isolate

A halophilic mangrove isolate identified by 16S rRNA sequence as a Bacillus spp. was found to be capable of using a broad range of carbon sources including monosaccharides (glucose and fructose), disaccharides (sucrose), pentoses (xylose and arabinose), various organic acids (acetic acid, propionic acid and octanoic acid) and even the acid pre-treated liquor (APL) of sugarcane trash, a lignocellulosic biomass, for growth and the production of polyhydroxyalkanoates (PHAs) such as poly(3-hydroxybutyrate, P3HB), poly(3-hydroxybutyrate-co-3-hydroxyvalerate, PHBV), and 4-hydroxyhexanoate, 4HHX). The study describes the innate ability of a wild-type culture for PHBV production by both propionate dependent and propionate independent pathways. The biopolymer was extracted and characterized physico-chemically. The PHBV yield from glucose was estimated to be 73% of biomass weight with a high 3-hydroxyvalerate fraction of 48mol%. Thereafter, spherical homogenous PHBV nanoparticles of ∼164nm size were prepared for future applications.

Molecular cloning, overexpression and biochemical characterization of hypothetical β‐lactamases of Mycobacterium tuberculosis H37Rv

Aim:  Molecular cloning, overexpression and biochemical characterization of the genes from the Mycobacterium tuberculosis H37Rv genome having hypothetical β‐lactamases activity.

Encapsulated Lactococcus lactis with enhanced gastrointestinal survival for the development of folate enriched functional foods

Two lactic acid bacteria (LAB) isolated from cows milk were identified as Lactococcus lactis strains and designated as L. lactis CM22 and L. lactis CM28. They were immobilised by co-encapsulation using alginate and mannitol and by hybrid entrapment with skim milk, glycerol, CaCO3 and alginate. The encapsulated cells survived better in simulated gastrointestinal conditions compared to the free cells. The percentage survival of probiotics encapsulated by hybrid entrapment method was 62.74% for L. lactis CM22 and 68% for L. lactis CM28. Studies to check their efficacy in fermentative fortification of skim milk and ice cream revealed an enhancement in folate level.

Engineering of Corynebacterium glutamicum for xylitol production from lignocellulosic pentose sugars

Xylitol is a non-fermentable sugar alcohol used as sweetener. Corynebacterium glutamicum ATCC13032 was metabolically engineered for xylitol production from the lignocellulosic pentose sugars xylose and arabinose. Direct conversion of xylose to xylitol was achieved through the heterologous expression of NAD(P)H-dependent xylose reductase (xr) gene from Rhodotorula mucilaginosa. Xylitol synthesis from arabinose was attained through polycistronic expression of l-arabinose isomerase (araA), d-psicose 3 epimerase (dpe) and l-xylulose reductase (lxr) genes from Escherichia coli, Agrobacterium tumefaciens and Mycobacterium smegmatis, respectively. Expression of xr and the synthetic araA-dpe-lxr operon under the control of IPTG-inducible Ptac promoter enabled production of xylitol from both xylose and arabinose in the mineral (CGXII) medium with glucose as carbon source. Additional expression of a pentose transporter (araTF) gene enhanced xylitol production by about four-fold compared to the parent strain. The constructed strain Cg-ax3 produced 6.7±0.4g/L of xylitol in batch fermentations and 31±0.5g/L of xylitol in fed-batch fermentations with a specific productivity of 0.28±0.05g/g cdw/h. The strain Cg-ax3 was also validated for xylitol production from pentose rich, acid pre-treated liquor of sorghum stover (SAPL) and the results were comparable in both SAPL (27±0.3g/L) and mineral medium (31±0.5g/L).