P. citrinum

The ACS function is known only in higher plants. The activity of ACS isozymes is a key regulatory factor of ethylene biosynthesis pathway. In general, microorganisms liberate ethylene but their ethylene synthesis pathways do not involve ACC as an intermediate. Penicillium citrinum is the first reported microorganism that is able to synthesize ACC from SAM and to degrade it into ammonia and a-ketobutyrate, not to ethylene. ACS from P. citrinum shows a 100-fold higher for SAM than its plant counterparts. ... 

The volatile oil of cumin, which is a mixture of about 32 components, principally cuminaldehyde (40.7%), terpinene (16.7%) and p-cymene (14.5%), inhibits Curvularia lunata and F. moniliforme by 100%, while the acetone extract is 85% effective in inhibiting the mycelial growth of A. ochraceus, A. flavus and P. citrinum (Singh et al., 2006). 

Patulin and citrinin are both produced by Penicillium species. Citrinin was first isolated from P. citrinum, from which it derived its name. Today, it is known that apart from Penicillium species like P. citreonigrum, P. citrinum, P. expansum, and P. verrucosum, citrinin is also produced by other species like A. candidus, A. terreus, and Monascus purpureus or M. ruber (Weidenborner, 2001). The occurrence of citrinin is mainly associated with rice and other cereals, but citrinin has also been detected in raisins (Meister, 2003) and in apples (Martins et al., 2002). 

The search for a suitable compound took 2 years and involved more than 6,000 microbes. The second mould shown to inhibit Upid synthesis was Penicillium citrinum. The active compound from P. citrinum was ML-236B (Mevastatin) capable of inhibiting Upid synthesis from either C-HMG CoA, or " C-acetate. However, there was no inhibitory effect on Upid production from H-labeled mevalonate. From this, it was possible to deduce that mevastatin did, in fact, inhibit the enzyme HMG CoA reductase. Two moulds were found to meet the requirements. Firstly Pythium ulti-mum was found to produce a substance caUed citrinin that was shown to irreversibly inhibit HMG CoA reductase. 

Citrinin (9.22) is a widespread mycotoxin that is formed by many Penicillium and Aspergillus species, particularly P. citrinum, P. expansum and P. roqueforti. It was first isolated in 1931 by the Raistrick group and described as an antibiotic. It has been shown to have carcinogenic effects and to produce kidney damage. Evidence for its structure and biosynthesis is discussed in Chapter 4. 

In addition to mevastatin and lovastatin, several other related derivatives showing inhibitory activities against HMG-CoA reductase were isolated from cultures of the fungi mentioned above. ML-236A (4), ML-236C (5) and dihydrocompactin (6) have been isolated from P. citrinum [23,30],... 

Compactin (90a), isolated from Penicillium brevicompactum and P.citrinum (J, 147), has been synthesized in optically active form as summarised in... 

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